[Qemu-devel] [PATCH v6 0/2] dump: let dump_error return error reason to caller

[Qemu-devel] [PATCH v6 0/2] dump: let dump_error return error reason to caller

[zhanghailiang]

Hi,

In original code, Function dump_error ignores its second parameter which contains
error reason, it is better to return the error message to the caller.

Here we use error_setg to return the error info to caller.
And at the same time, we turn functions like write_elf64_note() to void,
Because functions shouldn't return an error code _and_ an Error object.
After this modification the code will be more clean. 

v5 -> v6
- Don't check *errp directly, if errp is NULL, there will be an error,
  Instead, check a local variable *local_err (Markus Armbruster) 
v4 -> v5:
- Turn functions like write_elf64_note() to void (Luiz Capitulino)
v3 -> v4:
- Adjust the errp argument to the end 
- Remove trailing '.' in error messages
v2 -> v3:
- Drop the '\n' in the message when call dump_error(Eric Blake) 
v1 -> v2:
- Return the error reason to the caller (Luiz Capitulino)

zhanghailiang (2):
  dump: let dump_error return error info to caller
  dump: Don't return error code when return an Error object

 dump.c | 382 +++++++++++++++++++++++++++++++----------------------------------
 1 file changed, 182 insertions(+), 200 deletions(-)

-- 
1.7.12.4

[Qemu-devel] [PATCH v6 1/2] dump: let dump_error return error info to caller

[zhanghailiang]

The second parameter of dump_error is unused, but one purpose of
using this function is to report the error info.

Use error_set to return the error info to the caller.

Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
---
 dump.c | 165 ++++++++++++++++++++++++++++++++---------------------------------
 1 file changed, 82 insertions(+), 83 deletions(-)

diff --git a/dump.c b/dump.c
index 71d3e94..07d2300 100644
--- a/dump.c
+++ b/dump.c
@@ -81,9 +81,10 @@ static int dump_cleanup(DumpState *s)
     return 0;
 }
 
-static void dump_error(DumpState *s, const char *reason)
+static void dump_error(DumpState *s, const char *reason, Error **errp)
 {
     dump_cleanup(s);
+    error_setg(errp, "%s", reason);
 }
 
 static int fd_write_vmcore(const void *buf, size_t size, void *opaque)
@@ -99,7 +100,7 @@ static int fd_write_vmcore(const void *buf, size_t size, void *opaque)
     return 0;
 }
 
-static int write_elf64_header(DumpState *s)
+static int write_elf64_header(DumpState *s, Error **errp)
 {
     Elf64_Ehdr elf_header;
     int ret;
@@ -126,14 +127,14 @@ static int write_elf64_header(DumpState *s)
 
     ret = fd_write_vmcore(&elf_header, sizeof(elf_header), s);
     if (ret < 0) {
-        dump_error(s, "dump: failed to write elf header.\n");
+        dump_error(s, "dump: failed to write elf header", errp);
         return -1;
     }
 
     return 0;
 }
 
-static int write_elf32_header(DumpState *s)
+static int write_elf32_header(DumpState *s, Error **errp)
 {
     Elf32_Ehdr elf_header;
     int ret;
@@ -160,7 +161,7 @@ static int write_elf32_header(DumpState *s)
 
     ret = fd_write_vmcore(&elf_header, sizeof(elf_header), s);
     if (ret < 0) {
-        dump_error(s, "dump: failed to write elf header.\n");
+        dump_error(s, "dump: failed to write elf header", errp);
         return -1;
     }
 
@@ -169,7 +170,7 @@ static int write_elf32_header(DumpState *s)
 
 static int write_elf64_load(DumpState *s, MemoryMapping *memory_mapping,
                             int phdr_index, hwaddr offset,
-                            hwaddr filesz)
+                            hwaddr filesz, Error **errp)
 {
     Elf64_Phdr phdr;
     int ret;
@@ -186,7 +187,7 @@ static int write_elf64_load(DumpState *s, MemoryMapping *memory_mapping,
 
     ret = fd_write_vmcore(&phdr, sizeof(Elf64_Phdr), s);
     if (ret < 0) {
-        dump_error(s, "dump: failed to write program header table.\n");
+        dump_error(s, "dump: failed to write program header table", errp);
         return -1;
     }
 
@@ -195,7 +196,7 @@ static int write_elf64_load(DumpState *s, MemoryMapping *memory_mapping,
 
 static int write_elf32_load(DumpState *s, MemoryMapping *memory_mapping,
                             int phdr_index, hwaddr offset,
-                            hwaddr filesz)
+                            hwaddr filesz, Error **errp)
 {
     Elf32_Phdr phdr;
     int ret;
@@ -212,14 +213,14 @@ static int write_elf32_load(DumpState *s, MemoryMapping *memory_mapping,
 
     ret = fd_write_vmcore(&phdr, sizeof(Elf32_Phdr), s);
     if (ret < 0) {
-        dump_error(s, "dump: failed to write program header table.\n");
+        dump_error(s, "dump: failed to write program header table", errp);
         return -1;
     }
 
     return 0;
 }
 
-static int write_elf64_note(DumpState *s)
+static int write_elf64_note(DumpState *s, Error **errp)
 {
     Elf64_Phdr phdr;
     hwaddr begin = s->memory_offset - s->note_size;
@@ -235,7 +236,7 @@ static int write_elf64_note(DumpState *s)
 
     ret = fd_write_vmcore(&phdr, sizeof(Elf64_Phdr), s);
     if (ret < 0) {
-        dump_error(s, "dump: failed to write program header table.\n");
+        dump_error(s, "dump: failed to write program header table", errp);
         return -1;
     }
 
@@ -247,7 +248,8 @@ static inline int cpu_index(CPUState *cpu)
     return cpu->cpu_index + 1;
 }
 
-static int write_elf64_notes(WriteCoreDumpFunction f, DumpState *s)
+static int write_elf64_notes(WriteCoreDumpFunction f, DumpState *s,
+                             Error **errp)
 {
     CPUState *cpu;
     int ret;
@@ -257,7 +259,7 @@ static int write_elf64_notes(WriteCoreDumpFunction f, DumpState *s)
         id = cpu_index(cpu);
         ret = cpu_write_elf64_note(f, cpu, id, s);
         if (ret < 0) {
-            dump_error(s, "dump: failed to write elf notes.\n");
+            dump_error(s, "dump: failed to write elf notes", errp);
             return -1;
         }
     }
@@ -265,7 +267,7 @@ static int write_elf64_notes(WriteCoreDumpFunction f, DumpState *s)
     CPU_FOREACH(cpu) {
         ret = cpu_write_elf64_qemunote(f, cpu, s);
         if (ret < 0) {
-            dump_error(s, "dump: failed to write CPU status.\n");
+            dump_error(s, "dump: failed to write CPU status", errp);
             return -1;
         }
     }
@@ -273,7 +275,7 @@ static int write_elf64_notes(WriteCoreDumpFunction f, DumpState *s)
     return 0;
 }
 
-static int write_elf32_note(DumpState *s)
+static int write_elf32_note(DumpState *s, Error **errp)
 {
     hwaddr begin = s->memory_offset - s->note_size;
     Elf32_Phdr phdr;
@@ -289,14 +291,15 @@ static int write_elf32_note(DumpState *s)
 
     ret = fd_write_vmcore(&phdr, sizeof(Elf32_Phdr), s);
     if (ret < 0) {
-        dump_error(s, "dump: failed to write program header table.\n");
+        dump_error(s, "dump: failed to write program header table", errp);
         return -1;
     }
 
     return 0;
 }
 
-static int write_elf32_notes(WriteCoreDumpFunction f, DumpState *s)
+static int write_elf32_notes(WriteCoreDumpFunction f, DumpState *s,
+                             Error **errp)
 {
     CPUState *cpu;
     int ret;
@@ -306,7 +309,7 @@ static int write_elf32_notes(WriteCoreDumpFunction f, DumpState *s)
         id = cpu_index(cpu);
         ret = cpu_write_elf32_note(f, cpu, id, s);
         if (ret < 0) {
-            dump_error(s, "dump: failed to write elf notes.\n");
+            dump_error(s, "dump: failed to write elf notes", errp);
             return -1;
         }
     }
@@ -314,7 +317,7 @@ static int write_elf32_notes(WriteCoreDumpFunction f, DumpState *s)
     CPU_FOREACH(cpu) {
         ret = cpu_write_elf32_qemunote(f, cpu, s);
         if (ret < 0) {
-            dump_error(s, "dump: failed to write CPU status.\n");
+            dump_error(s, "dump: failed to write CPU status", errp);
             return -1;
         }
     }
@@ -322,7 +325,7 @@ static int write_elf32_notes(WriteCoreDumpFunction f, DumpState *s)
     return 0;
 }
 
-static int write_elf_section(DumpState *s, int type)
+static int write_elf_section(DumpState *s, int type, Error **errp)
 {
     Elf32_Shdr shdr32;
     Elf64_Shdr shdr64;
@@ -344,20 +347,20 @@ static int write_elf_section(DumpState *s, int type)
 
     ret = fd_write_vmcore(&shdr, shdr_size, s);
     if (ret < 0) {
-        dump_error(s, "dump: failed to write section header table.\n");
+        dump_error(s, "dump: failed to write section header table", errp);
         return -1;
     }
 
     return 0;
 }
 
-static int write_data(DumpState *s, void *buf, int length)
+static int write_data(DumpState *s, void *buf, int length, Error **errp)
 {
     int ret;
 
     ret = fd_write_vmcore(buf, length, s);
     if (ret < 0) {
-        dump_error(s, "dump: failed to save memory.\n");
+        dump_error(s, "dump: failed to save memory", errp);
         return -1;
     }
 
@@ -366,14 +369,14 @@ static int write_data(DumpState *s, void *buf, int length)
 
 /* write the memroy to vmcore. 1 page per I/O. */
 static int write_memory(DumpState *s, GuestPhysBlock *block, ram_addr_t start,
-                        int64_t size)
+                        int64_t size, Error **errp)
 {
     int64_t i;
     int ret;
 
     for (i = 0; i < size / TARGET_PAGE_SIZE; i++) {
         ret = write_data(s, block->host_addr + start + i * TARGET_PAGE_SIZE,
-                         TARGET_PAGE_SIZE);
+                         TARGET_PAGE_SIZE, errp);
         if (ret < 0) {
             return ret;
         }
@@ -381,7 +384,7 @@ static int write_memory(DumpState *s, GuestPhysBlock *block, ram_addr_t start,
 
     if ((size % TARGET_PAGE_SIZE) != 0) {
         ret = write_data(s, block->host_addr + start + i * TARGET_PAGE_SIZE,
-                         size % TARGET_PAGE_SIZE);
+                         size % TARGET_PAGE_SIZE, errp);
         if (ret < 0) {
             return ret;
         }
@@ -452,7 +455,7 @@ static void get_offset_range(hwaddr phys_addr,
     }
 }
 
-static int write_elf_loads(DumpState *s)
+static int write_elf_loads(DumpState *s, Error **errp)
 {
     hwaddr offset, filesz;
     MemoryMapping *memory_mapping;
@@ -472,10 +475,10 @@ static int write_elf_loads(DumpState *s)
                          s, &offset, &filesz);
         if (s->dump_info.d_class == ELFCLASS64) {
             ret = write_elf64_load(s, memory_mapping, phdr_index++, offset,
-                                   filesz);
+                                   filesz, errp);
         } else {
             ret = write_elf32_load(s, memory_mapping, phdr_index++, offset,
-                                   filesz);
+                                   filesz, errp);
         }
 
         if (ret < 0) {
@@ -491,7 +494,7 @@ static int write_elf_loads(DumpState *s)
 }
 
 /* write elf header, PT_NOTE and elf note to vmcore. */
-static int dump_begin(DumpState *s)
+static int dump_begin(DumpState *s, Error **errp)
 {
     int ret;
 
@@ -521,9 +524,9 @@ static int dump_begin(DumpState *s)
 
     /* write elf header to vmcore */
     if (s->dump_info.d_class == ELFCLASS64) {
-        ret = write_elf64_header(s);
+        ret = write_elf64_header(s, errp);
     } else {
-        ret = write_elf32_header(s);
+        ret = write_elf32_header(s, errp);
     }
     if (ret < 0) {
         return -1;
@@ -531,47 +534,47 @@ static int dump_begin(DumpState *s)
 
     if (s->dump_info.d_class == ELFCLASS64) {
         /* write PT_NOTE to vmcore */
-        if (write_elf64_note(s) < 0) {
+        if (write_elf64_note(s, errp) < 0) {
             return -1;
         }
 
         /* write all PT_LOAD to vmcore */
-        if (write_elf_loads(s) < 0) {
+        if (write_elf_loads(s, errp) < 0) {
             return -1;
         }
 
         /* write section to vmcore */
         if (s->have_section) {
-            if (write_elf_section(s, 1) < 0) {
+            if (write_elf_section(s, 1, errp) < 0) {
                 return -1;
             }
         }
 
         /* write notes to vmcore */
-        if (write_elf64_notes(fd_write_vmcore, s) < 0) {
+        if (write_elf64_notes(fd_write_vmcore, s, errp) < 0) {
             return -1;
         }
 
     } else {
         /* write PT_NOTE to vmcore */
-        if (write_elf32_note(s) < 0) {
+        if (write_elf32_note(s, errp) < 0) {
             return -1;
         }
 
         /* write all PT_LOAD to vmcore */
-        if (write_elf_loads(s) < 0) {
+        if (write_elf_loads(s, errp) < 0) {
             return -1;
         }
 
         /* write section to vmcore */
         if (s->have_section) {
-            if (write_elf_section(s, 0) < 0) {
+            if (write_elf_section(s, 0, errp) < 0) {
                 return -1;
             }
         }
 
         /* write notes to vmcore */
-        if (write_elf32_notes(fd_write_vmcore, s) < 0) {
+        if (write_elf32_notes(fd_write_vmcore, s, errp) < 0) {
             return -1;
         }
     }
@@ -614,7 +617,7 @@ static int get_next_block(DumpState *s, GuestPhysBlock *block)
 }
 
 /* write all memory to vmcore */
-static int dump_iterate(DumpState *s)
+static int dump_iterate(DumpState *s, Error **errp)
 {
     GuestPhysBlock *block;
     int64_t size;
@@ -630,7 +633,7 @@ static int dump_iterate(DumpState *s)
                 size -= block->target_end - (s->begin + s->length);
             }
         }
-        ret = write_memory(s, block, s->start, size);
+        ret = write_memory(s, block, s->start, size, errp);
         if (ret == -1) {
             return ret;
         }
@@ -643,16 +646,16 @@ static int dump_iterate(DumpState *s)
     }
 }
 
-static int create_vmcore(DumpState *s)
+static int create_vmcore(DumpState *s, Error **errp)
 {
     int ret;
 
-    ret = dump_begin(s);
+    ret = dump_begin(s, errp);
     if (ret < 0) {
         return -1;
     }
 
-    ret = dump_iterate(s);
+    ret = dump_iterate(s, errp);
     if (ret < 0) {
         return -1;
     }
@@ -738,7 +741,7 @@ static int buf_write_note(const void *buf, size_t size, void *opaque)
 }
 
 /* write common header, sub header and elf note to vmcore */
-static int create_header32(DumpState *s)
+static int create_header32(DumpState *s, Error **errp)
 {
     int ret = 0;
     DiskDumpHeader32 *dh = NULL;
@@ -784,7 +787,7 @@ static int create_header32(DumpState *s)
     dh->status = cpu_to_dump32(s, status);
 
     if (write_buffer(s->fd, 0, dh, size) < 0) {
-        dump_error(s, "dump: failed to write disk dump header.\n");
+        dump_error(s, "dump: failed to write disk dump header", errp);
         ret = -1;
         goto out;
     }
@@ -804,7 +807,7 @@ static int create_header32(DumpState *s)
 
     if (write_buffer(s->fd, DISKDUMP_HEADER_BLOCKS *
                      block_size, kh, size) < 0) {
-        dump_error(s, "dump: failed to write kdump sub header.\n");
+        dump_error(s, "dump: failed to write kdump sub header", errp);
         ret = -1;
         goto out;
     }
@@ -814,14 +817,14 @@ static int create_header32(DumpState *s)
     s->note_buf_offset = 0;
 
     /* use s->note_buf to store notes temporarily */
-    if (write_elf32_notes(buf_write_note, s) < 0) {
+    if (write_elf32_notes(buf_write_note, s, errp) < 0) {
         ret = -1;
         goto out;
     }
 
     if (write_buffer(s->fd, offset_note, s->note_buf,
                      s->note_size) < 0) {
-        dump_error(s, "dump: failed to write notes");
+        dump_error(s, "dump: failed to write notes", errp);
         ret = -1;
         goto out;
     }
@@ -843,7 +846,7 @@ out:
 }
 
 /* write common header, sub header and elf note to vmcore */
-static int create_header64(DumpState *s)
+static int create_header64(DumpState *s, Error **errp)
 {
     int ret = 0;
     DiskDumpHeader64 *dh = NULL;
@@ -889,7 +892,7 @@ static int create_header64(DumpState *s)
     dh->status = cpu_to_dump32(s, status);
 
     if (write_buffer(s->fd, 0, dh, size) < 0) {
-        dump_error(s, "dump: failed to write disk dump header.\n");
+        dump_error(s, "dump: failed to write disk dump header", errp);
         ret = -1;
         goto out;
     }
@@ -909,7 +912,7 @@ static int create_header64(DumpState *s)
 
     if (write_buffer(s->fd, DISKDUMP_HEADER_BLOCKS *
                      block_size, kh, size) < 0) {
-        dump_error(s, "dump: failed to write kdump sub header.\n");
+        dump_error(s, "dump: failed to write kdump sub header", errp);
         ret = -1;
         goto out;
     }
@@ -919,14 +922,14 @@ static int create_header64(DumpState *s)
     s->note_buf_offset = 0;
 
     /* use s->note_buf to store notes temporarily */
-    if (write_elf64_notes(buf_write_note, s) < 0) {
+    if (write_elf64_notes(buf_write_note, s, errp) < 0) {
         ret = -1;
         goto out;
     }
 
     if (write_buffer(s->fd, offset_note, s->note_buf,
                      s->note_size) < 0) {
-        dump_error(s, "dump: failed to write notes");
+        dump_error(s, "dump: failed to write notes", errp);
         ret = -1;
         goto out;
     }
@@ -947,12 +950,12 @@ out:
     return ret;
 }
 
-static int write_dump_header(DumpState *s)
+static int write_dump_header(DumpState *s, Error **errp)
 {
     if (s->dump_info.d_class == ELFCLASS32) {
-        return create_header32(s);
+        return create_header32(s, errp);
     } else {
-        return create_header64(s);
+        return create_header64(s, errp);
     }
 }
 
@@ -1066,7 +1069,7 @@ static bool get_next_page(GuestPhysBlock **blockptr, uint64_t *pfnptr,
     return true;
 }
 
-static int write_dump_bitmap(DumpState *s)
+static int write_dump_bitmap(DumpState *s, Error **errp)
 {
     int ret = 0;
     uint64_t last_pfn, pfn;
@@ -1087,7 +1090,7 @@ static int write_dump_bitmap(DumpState *s)
     while (get_next_page(&block_iter, &pfn, NULL, s)) {
         ret = set_dump_bitmap(last_pfn, pfn, true, dump_bitmap_buf, s);
         if (ret < 0) {
-            dump_error(s, "dump: failed to set dump_bitmap.\n");
+            dump_error(s, "dump: failed to set dump_bitmap", errp);
             ret = -1;
             goto out;
         }
@@ -1105,7 +1108,7 @@ static int write_dump_bitmap(DumpState *s)
         ret = set_dump_bitmap(last_pfn, last_pfn + PFN_BUFBITMAP, false,
                               dump_bitmap_buf, s);
         if (ret < 0) {
-            dump_error(s, "dump: failed to sync dump_bitmap.\n");
+            dump_error(s, "dump: failed to sync dump_bitmap", errp);
             ret = -1;
             goto out;
         }
@@ -1197,7 +1200,7 @@ static inline bool is_zero_page(const uint8_t *buf, size_t page_size)
     return buffer_is_zero(buf, page_size);
 }
 
-static int write_dump_pages(DumpState *s)
+static int write_dump_pages(DumpState *s, Error **errp)
 {
     int ret = 0;
     DataCache page_desc, page_data;
@@ -1241,7 +1244,7 @@ static int write_dump_pages(DumpState *s)
     ret = write_cache(&page_data, buf, TARGET_PAGE_SIZE, false);
     g_free(buf);
     if (ret < 0) {
-        dump_error(s, "dump: failed to write page data(zero page).\n");
+        dump_error(s, "dump: failed to write page data (zero page)", errp);
         goto out;
     }
 
@@ -1257,7 +1260,7 @@ static int write_dump_pages(DumpState *s)
             ret = write_cache(&page_desc, &pd_zero, sizeof(PageDescriptor),
                               false);
             if (ret < 0) {
-                dump_error(s, "dump: failed to write page desc.\n");
+                dump_error(s, "dump: failed to write page desc", errp);
                 goto out;
             }
         } else {
@@ -1282,7 +1285,7 @@ static int write_dump_pages(DumpState *s)
 
                 ret = write_cache(&page_data, buf_out, size_out, false);
                 if (ret < 0) {
-                    dump_error(s, "dump: failed to write page data.\n");
+                    dump_error(s, "dump: failed to write page data", errp);
                     goto out;
                 }
 #ifdef CONFIG_LZO
@@ -1295,7 +1298,7 @@ static int write_dump_pages(DumpState *s)
 
                 ret = write_cache(&page_data, buf_out, size_out, false);
                 if (ret < 0) {
-                    dump_error(s, "dump: failed to write page data.\n");
+                    dump_error(s, "dump: failed to write page data", errp);
                     goto out;
                 }
 #endif
@@ -1309,7 +1312,7 @@ static int write_dump_pages(DumpState *s)
 
                 ret = write_cache(&page_data, buf_out, size_out, false);
                 if (ret < 0) {
-                    dump_error(s, "dump: failed to write page data.\n");
+                    dump_error(s, "dump: failed to write page data", errp);
                     goto out;
                 }
 #endif
@@ -1324,7 +1327,7 @@ static int write_dump_pages(DumpState *s)
 
                 ret = write_cache(&page_data, buf, TARGET_PAGE_SIZE, false);
                 if (ret < 0) {
-                    dump_error(s, "dump: failed to write page data.\n");
+                    dump_error(s, "dump: failed to write page data", errp);
                     goto out;
                 }
             }
@@ -1336,7 +1339,7 @@ static int write_dump_pages(DumpState *s)
 
             ret = write_cache(&page_desc, &pd, sizeof(PageDescriptor), false);
             if (ret < 0) {
-                dump_error(s, "dump: failed to write page desc.\n");
+                dump_error(s, "dump: failed to write page desc", errp);
                 goto out;
             }
         }
@@ -1344,12 +1347,12 @@ static int write_dump_pages(DumpState *s)
 
     ret = write_cache(&page_desc, NULL, 0, true);
     if (ret < 0) {
-        dump_error(s, "dump: failed to sync cache for page_desc.\n");
+        dump_error(s, "dump: failed to sync cache for page_desc", errp);
         goto out;
     }
     ret = write_cache(&page_data, NULL, 0, true);
     if (ret < 0) {
-        dump_error(s, "dump: failed to sync cache for page_data.\n");
+        dump_error(s, "dump: failed to sync cache for page_data", errp);
         goto out;
     }
 
@@ -1366,7 +1369,7 @@ out:
     return ret;
 }
 
-static int create_kdump_vmcore(DumpState *s)
+static int create_kdump_vmcore(DumpState *s, Error **errp)
 {
     int ret;
 
@@ -1394,28 +1397,28 @@ static int create_kdump_vmcore(DumpState *s)
 
     ret = write_start_flat_header(s->fd);
     if (ret < 0) {
-        dump_error(s, "dump: failed to write start flat header.\n");
+        dump_error(s, "dump: failed to write start flat header", errp);
         return -1;
     }
 
-    ret = write_dump_header(s);
+    ret = write_dump_header(s, errp);
     if (ret < 0) {
         return -1;
     }
 
-    ret = write_dump_bitmap(s);
+    ret = write_dump_bitmap(s, errp);
     if (ret < 0) {
         return -1;
     }
 
-    ret = write_dump_pages(s);
+    ret = write_dump_pages(s, errp);
     if (ret < 0) {
         return -1;
     }
 
     ret = write_end_flat_header(s->fd);
     if (ret < 0) {
-        dump_error(s, "dump: failed to write end flat header.\n");
+        dump_error(s, "dump: failed to write end flat header", errp);
         return -1;
     }
 
@@ -1699,13 +1702,9 @@ void qmp_dump_guest_memory(bool paging, const char *file, bool has_begin,
     }
 
     if (has_format && format != DUMP_GUEST_MEMORY_FORMAT_ELF) {
-        if (create_kdump_vmcore(s) < 0) {
-            error_set(errp, QERR_IO_ERROR);
-        }
+        create_kdump_vmcore(s, errp);
     } else {
-        if (create_vmcore(s) < 0) {
-            error_set(errp, QERR_IO_ERROR);
-        }
+        create_vmcore(s, errp);
     }
 
     g_free(s);
-- 
1.7.12.4

Re: [Qemu-devel] [PATCH v6 1/2] dump: let dump_error return error info to caller

[Markus Armbruster]

zhanghailiang <zhang.zhanghailiang@huawei.com> writes:

> The second parameter of dump_error is unused, but one purpose of
> using this function is to report the error info.
>
> Use error_set to return the error info to the caller.
>
> Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>

The commit message doesn't explain this patch's benefit clearly.
Suggest:

    dump: Propagate errors into qmp_dump_guest_memory()

    The code calls dump_error() on error, and even passes it a suitable
    message.  However, the message is thrown away, and its callers pass
    up only success/failure.  All qmp_dump_guest_memory() can do is set
    a generic error.

    Propagate the errors properly, so qmp_dump_guest_memory() can return
    a more useful error.

With a commit message like that:

Reviewed-by: Markus Armbruster <armbru@redhat.com>

Re: [Qemu-devel] [PATCH v6 1/2] dump: let dump_error return error info to caller

[zhanghailiang]

On 2014/9/29 15:48, Markus Armbruster wrote:
> zhanghailiang <zhang.zhanghailiang@huawei.com> writes:
>
>> The second parameter of dump_error is unused, but one purpose of
>> using this function is to report the error info.
>>
>> Use error_set to return the error info to the caller.
>>
>> Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
>
> The commit message doesn't explain this patch's benefit clearly.
> Suggest:
>
>      dump: Propagate errors into qmp_dump_guest_memory()
>
>      The code calls dump_error() on error, and even passes it a suitable
>      message.  However, the message is thrown away, and its callers pass
>      up only success/failure.  All qmp_dump_guest_memory() can do is set
>      a generic error.
>
>      Propagate the errors properly, so qmp_dump_guest_memory() can return
>      a more useful error.
>
> With a commit message like that:
>
> Reviewed-by: Markus Armbruster <armbru@redhat.com>
>
>

OK, Will fix like that, and submit V7, thanks very much;)

[Qemu-devel] [PATCH v6 2/2] dump: Don't return error code when return an Error object

[zhanghailiang]

Functions shouldn't return an error code and an Error object at the same time.
Turn all these functions that returning Error object to void.
We also judge if a function success or fail by reference to the local_err.

Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
---
 dump.c | 313 +++++++++++++++++++++++++++++++----------------------------------
 1 file changed, 148 insertions(+), 165 deletions(-)

diff --git a/dump.c b/dump.c
index 07d2300..a6188b3 100644
--- a/dump.c
+++ b/dump.c
@@ -100,7 +100,7 @@ static int fd_write_vmcore(const void *buf, size_t size, void *opaque)
     return 0;
 }
 
-static int write_elf64_header(DumpState *s, Error **errp)
+static void write_elf64_header(DumpState *s, Error **errp)
 {
     Elf64_Ehdr elf_header;
     int ret;
@@ -128,13 +128,10 @@ static int write_elf64_header(DumpState *s, Error **errp)
     ret = fd_write_vmcore(&elf_header, sizeof(elf_header), s);
     if (ret < 0) {
         dump_error(s, "dump: failed to write elf header", errp);
-        return -1;
     }
-
-    return 0;
 }
 
-static int write_elf32_header(DumpState *s, Error **errp)
+static void write_elf32_header(DumpState *s, Error **errp)
 {
     Elf32_Ehdr elf_header;
     int ret;
@@ -162,13 +159,10 @@ static int write_elf32_header(DumpState *s, Error **errp)
     ret = fd_write_vmcore(&elf_header, sizeof(elf_header), s);
     if (ret < 0) {
         dump_error(s, "dump: failed to write elf header", errp);
-        return -1;
     }
-
-    return 0;
 }
 
-static int write_elf64_load(DumpState *s, MemoryMapping *memory_mapping,
+static void write_elf64_load(DumpState *s, MemoryMapping *memory_mapping,
                              int phdr_index, hwaddr offset,
                              hwaddr filesz, Error **errp)
 {
@@ -188,15 +182,12 @@ static int write_elf64_load(DumpState *s, MemoryMapping *memory_mapping,
     ret = fd_write_vmcore(&phdr, sizeof(Elf64_Phdr), s);
     if (ret < 0) {
         dump_error(s, "dump: failed to write program header table", errp);
-        return -1;
     }
-
-    return 0;
 }
 
-static int write_elf32_load(DumpState *s, MemoryMapping *memory_mapping,
-                            int phdr_index, hwaddr offset,
-                            hwaddr filesz, Error **errp)
+static void write_elf32_load(DumpState *s, MemoryMapping *memory_mapping,
+                             int phdr_index, hwaddr offset,
+                             hwaddr filesz, Error **errp)
 {
     Elf32_Phdr phdr;
     int ret;
@@ -214,13 +205,10 @@ static int write_elf32_load(DumpState *s, MemoryMapping *memory_mapping,
     ret = fd_write_vmcore(&phdr, sizeof(Elf32_Phdr), s);
     if (ret < 0) {
         dump_error(s, "dump: failed to write program header table", errp);
-        return -1;
     }
-
-    return 0;
 }
 
-static int write_elf64_note(DumpState *s, Error **errp)
+static void write_elf64_note(DumpState *s, Error **errp)
 {
     Elf64_Phdr phdr;
     hwaddr begin = s->memory_offset - s->note_size;
@@ -237,10 +225,7 @@ static int write_elf64_note(DumpState *s, Error **errp)
     ret = fd_write_vmcore(&phdr, sizeof(Elf64_Phdr), s);
     if (ret < 0) {
         dump_error(s, "dump: failed to write program header table", errp);
-        return -1;
     }
-
-    return 0;
 }
 
 static inline int cpu_index(CPUState *cpu)
@@ -248,8 +233,8 @@ static inline int cpu_index(CPUState *cpu)
     return cpu->cpu_index + 1;
 }
 
-static int write_elf64_notes(WriteCoreDumpFunction f, DumpState *s,
-                             Error **errp)
+static void write_elf64_notes(WriteCoreDumpFunction f, DumpState *s,
+                              Error **errp)
 {
     CPUState *cpu;
     int ret;
@@ -260,7 +245,7 @@ static int write_elf64_notes(WriteCoreDumpFunction f, DumpState *s,
         ret = cpu_write_elf64_note(f, cpu, id, s);
         if (ret < 0) {
             dump_error(s, "dump: failed to write elf notes", errp);
-            return -1;
+            return;
         }
     }
 
@@ -268,14 +253,12 @@ static int write_elf64_notes(WriteCoreDumpFunction f, DumpState *s,
         ret = cpu_write_elf64_qemunote(f, cpu, s);
         if (ret < 0) {
             dump_error(s, "dump: failed to write CPU status", errp);
-            return -1;
+            return;
         }
     }
-
-    return 0;
 }
 
-static int write_elf32_note(DumpState *s, Error **errp)
+static void write_elf32_note(DumpState *s, Error **errp)
 {
     hwaddr begin = s->memory_offset - s->note_size;
     Elf32_Phdr phdr;
@@ -292,14 +275,11 @@ static int write_elf32_note(DumpState *s, Error **errp)
     ret = fd_write_vmcore(&phdr, sizeof(Elf32_Phdr), s);
     if (ret < 0) {
         dump_error(s, "dump: failed to write program header table", errp);
-        return -1;
     }
-
-    return 0;
 }
 
-static int write_elf32_notes(WriteCoreDumpFunction f, DumpState *s,
-                             Error **errp)
+static void write_elf32_notes(WriteCoreDumpFunction f, DumpState *s,
+                              Error **errp)
 {
     CPUState *cpu;
     int ret;
@@ -310,7 +290,7 @@ static int write_elf32_notes(WriteCoreDumpFunction f, DumpState *s,
         ret = cpu_write_elf32_note(f, cpu, id, s);
         if (ret < 0) {
             dump_error(s, "dump: failed to write elf notes", errp);
-            return -1;
+            return;
         }
     }
 
@@ -318,14 +298,12 @@ static int write_elf32_notes(WriteCoreDumpFunction f, DumpState *s,
         ret = cpu_write_elf32_qemunote(f, cpu, s);
         if (ret < 0) {
             dump_error(s, "dump: failed to write CPU status", errp);
-            return -1;
+            return;
         }
     }
-
-    return 0;
 }
 
-static int write_elf_section(DumpState *s, int type, Error **errp)
+static void write_elf_section(DumpState *s, int type, Error **errp)
 {
     Elf32_Shdr shdr32;
     Elf64_Shdr shdr64;
@@ -348,49 +326,45 @@ static int write_elf_section(DumpState *s, int type, Error **errp)
     ret = fd_write_vmcore(&shdr, shdr_size, s);
     if (ret < 0) {
         dump_error(s, "dump: failed to write section header table", errp);
-        return -1;
+        return;
     }
-
-    return 0;
 }
 
-static int write_data(DumpState *s, void *buf, int length, Error **errp)
+static void write_data(DumpState *s, void *buf, int length, Error **errp)
 {
     int ret;
 
     ret = fd_write_vmcore(buf, length, s);
     if (ret < 0) {
         dump_error(s, "dump: failed to save memory", errp);
-        return -1;
+        return;
     }
-
-    return 0;
 }
 
 /* write the memroy to vmcore. 1 page per I/O. */
-static int write_memory(DumpState *s, GuestPhysBlock *block, ram_addr_t start,
-                        int64_t size, Error **errp)
+static void write_memory(DumpState *s, GuestPhysBlock *block, ram_addr_t start,
+                         int64_t size, Error **errp)
 {
     int64_t i;
-    int ret;
+    Error *local_err = NULL;
 
     for (i = 0; i < size / TARGET_PAGE_SIZE; i++) {
-        ret = write_data(s, block->host_addr + start + i * TARGET_PAGE_SIZE,
-                         TARGET_PAGE_SIZE, errp);
-        if (ret < 0) {
-            return ret;
+        write_data(s, block->host_addr + start + i * TARGET_PAGE_SIZE,
+                   TARGET_PAGE_SIZE, &local_err);
+        if (local_err) {
+            error_propagate(errp, local_err);
+            return;
         }
     }
 
     if ((size % TARGET_PAGE_SIZE) != 0) {
-        ret = write_data(s, block->host_addr + start + i * TARGET_PAGE_SIZE,
-                         size % TARGET_PAGE_SIZE, errp);
-        if (ret < 0) {
-            return ret;
+        write_data(s, block->host_addr + start + i * TARGET_PAGE_SIZE,
+                   size % TARGET_PAGE_SIZE, &local_err);
+        if (local_err) {
+            error_propagate(errp, local_err);
+            return;
         }
     }
-
-    return 0;
 }
 
 /* get the memory's offset and size in the vmcore */
@@ -455,13 +429,13 @@ static void get_offset_range(hwaddr phys_addr,
     }
 }
 
-static int write_elf_loads(DumpState *s, Error **errp)
+static void write_elf_loads(DumpState *s, Error **errp)
 {
     hwaddr offset, filesz;
     MemoryMapping *memory_mapping;
     uint32_t phdr_index = 1;
-    int ret;
     uint32_t max_index;
+    Error *local_err = NULL;
 
     if (s->have_section) {
         max_index = s->sh_info;
@@ -474,29 +448,28 @@ static int write_elf_loads(DumpState *s, Error **errp)
                          memory_mapping->length,
                          s, &offset, &filesz);
         if (s->dump_info.d_class == ELFCLASS64) {
-            ret = write_elf64_load(s, memory_mapping, phdr_index++, offset,
-                                   filesz, errp);
+            write_elf64_load(s, memory_mapping, phdr_index++, offset,
+                             filesz, &local_err);
         } else {
-            ret = write_elf32_load(s, memory_mapping, phdr_index++, offset,
-                                   filesz, errp);
+            write_elf32_load(s, memory_mapping, phdr_index++, offset,
+                             filesz, &local_err);
         }
 
-        if (ret < 0) {
-            return -1;
+        if (local_err) {
+            error_propagate(errp, local_err);
+            return;
         }
 
         if (phdr_index >= max_index) {
             break;
         }
     }
-
-    return 0;
 }
 
 /* write elf header, PT_NOTE and elf note to vmcore. */
-static int dump_begin(DumpState *s, Error **errp)
+static void dump_begin(DumpState *s, Error **errp)
 {
-    int ret;
+    Error *local_err = NULL;
 
     /*
      * the vmcore's format is:
@@ -524,62 +497,76 @@ static int dump_begin(DumpState *s, Error **errp)
 
     /* write elf header to vmcore */
     if (s->dump_info.d_class == ELFCLASS64) {
-        ret = write_elf64_header(s, errp);
+        write_elf64_header(s, &local_err);
     } else {
-        ret = write_elf32_header(s, errp);
+        write_elf32_header(s, &local_err);
     }
-    if (ret < 0) {
-        return -1;
+    if (local_err) {
+        error_propagate(errp, local_err);
+        return;
     }
 
     if (s->dump_info.d_class == ELFCLASS64) {
         /* write PT_NOTE to vmcore */
-        if (write_elf64_note(s, errp) < 0) {
-            return -1;
+        write_elf64_note(s, &local_err);
+        if (local_err) {
+            error_propagate(errp, local_err);
+            return;
         }
 
         /* write all PT_LOAD to vmcore */
-        if (write_elf_loads(s, errp) < 0) {
-            return -1;
+        write_elf_loads(s, &local_err);
+        if (local_err) {
+            error_propagate(errp, local_err);
+            return;
         }
 
         /* write section to vmcore */
         if (s->have_section) {
-            if (write_elf_section(s, 1, errp) < 0) {
-                return -1;
+            write_elf_section(s, 1, &local_err);
+            if (local_err) {
+                error_propagate(errp, local_err);
+                return;
             }
         }
 
         /* write notes to vmcore */
-        if (write_elf64_notes(fd_write_vmcore, s, errp) < 0) {
-            return -1;
+        write_elf64_notes(fd_write_vmcore, s, &local_err);
+        if (local_err) {
+            error_propagate(errp, local_err);
+            return;
         }
-
     } else {
         /* write PT_NOTE to vmcore */
-        if (write_elf32_note(s, errp) < 0) {
-            return -1;
+        write_elf32_note(s, &local_err);
+        if (local_err) {
+            error_propagate(errp, local_err);
+            return;
         }
 
         /* write all PT_LOAD to vmcore */
-        if (write_elf_loads(s, errp) < 0) {
-            return -1;
+        write_elf_loads(s, &local_err);
+        if (local_err) {
+            error_propagate(errp, local_err);
+            return;
         }
 
         /* write section to vmcore */
         if (s->have_section) {
-            if (write_elf_section(s, 0, errp) < 0) {
-                return -1;
+            write_elf_section(s, 0, &local_err);
+            if (local_err) {
+                error_propagate(errp, local_err);
+                return;
             }
         }
 
         /* write notes to vmcore */
-        if (write_elf32_notes(fd_write_vmcore, s, errp) < 0) {
-            return -1;
+        write_elf32_notes(fd_write_vmcore, s, &local_err);
+        if (local_err) {
+            error_propagate(errp, local_err);
+            return;
         }
     }
-
-    return 0;
 }
 
 /* write PT_LOAD to vmcore */
@@ -617,11 +604,12 @@ static int get_next_block(DumpState *s, GuestPhysBlock *block)
 }
 
 /* write all memory to vmcore */
-static int dump_iterate(DumpState *s, Error **errp)
+static void dump_iterate(DumpState *s, Error **errp)
 {
     GuestPhysBlock *block;
     int64_t size;
     int ret;
+    Error *local_err = NULL;
 
     while (1) {
         block = s->next_block;
@@ -633,34 +621,35 @@ static int dump_iterate(DumpState *s, Error **errp)
                 size -= block->target_end - (s->begin + s->length);
             }
         }
-        ret = write_memory(s, block, s->start, size, errp);
-        if (ret == -1) {
-            return ret;
+        write_memory(s, block, s->start, size, &local_err);
+        if (local_err) {
+            error_propagate(errp, local_err);
+            return;
         }
 
         ret = get_next_block(s, block);
         if (ret == 1) {
             dump_completed(s);
-            return 0;
         }
     }
 }
 
-static int create_vmcore(DumpState *s, Error **errp)
+static void create_vmcore(DumpState *s, Error **errp)
 {
-    int ret;
+    Error *local_err = NULL;
 
-    ret = dump_begin(s, errp);
-    if (ret < 0) {
-        return -1;
+    dump_begin(s, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        return;
     }
 
-    ret = dump_iterate(s, errp);
-    if (ret < 0) {
-        return -1;
+    dump_iterate(s, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        return;
     }
 
-    return 0;
 }
 
 static int write_start_flat_header(int fd)
@@ -741,9 +730,8 @@ static int buf_write_note(const void *buf, size_t size, void *opaque)
 }
 
 /* write common header, sub header and elf note to vmcore */
-static int create_header32(DumpState *s, Error **errp)
+static void create_header32(DumpState *s, Error **errp)
 {
-    int ret = 0;
     DiskDumpHeader32 *dh = NULL;
     KdumpSubHeader32 *kh = NULL;
     size_t size;
@@ -752,6 +740,7 @@ static int create_header32(DumpState *s, Error **errp)
     uint32_t bitmap_blocks;
     uint32_t status = 0;
     uint64_t offset_note;
+    Error *local_err = NULL;
 
     /* write common header, the version of kdump-compressed format is 6th */
     size = sizeof(DiskDumpHeader32);
@@ -788,7 +777,6 @@ static int create_header32(DumpState *s, Error **errp)
 
     if (write_buffer(s->fd, 0, dh, size) < 0) {
         dump_error(s, "dump: failed to write disk dump header", errp);
-        ret = -1;
         goto out;
     }
 
@@ -808,7 +796,6 @@ static int create_header32(DumpState *s, Error **errp)
     if (write_buffer(s->fd, DISKDUMP_HEADER_BLOCKS *
                      block_size, kh, size) < 0) {
         dump_error(s, "dump: failed to write kdump sub header", errp);
-        ret = -1;
         goto out;
     }
 
@@ -817,15 +804,14 @@ static int create_header32(DumpState *s, Error **errp)
     s->note_buf_offset = 0;
 
     /* use s->note_buf to store notes temporarily */
-    if (write_elf32_notes(buf_write_note, s, errp) < 0) {
-        ret = -1;
+    write_elf32_notes(buf_write_note, s, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
         goto out;
     }
-
     if (write_buffer(s->fd, offset_note, s->note_buf,
                      s->note_size) < 0) {
         dump_error(s, "dump: failed to write notes", errp);
-        ret = -1;
         goto out;
     }
 
@@ -841,14 +827,11 @@ out:
     g_free(dh);
     g_free(kh);
     g_free(s->note_buf);
-
-    return ret;
 }
 
 /* write common header, sub header and elf note to vmcore */
-static int create_header64(DumpState *s, Error **errp)
+static void create_header64(DumpState *s, Error **errp)
 {
-    int ret = 0;
     DiskDumpHeader64 *dh = NULL;
     KdumpSubHeader64 *kh = NULL;
     size_t size;
@@ -857,6 +840,7 @@ static int create_header64(DumpState *s, Error **errp)
     uint32_t bitmap_blocks;
     uint32_t status = 0;
     uint64_t offset_note;
+    Error *local_err = NULL;
 
     /* write common header, the version of kdump-compressed format is 6th */
     size = sizeof(DiskDumpHeader64);
@@ -893,7 +877,6 @@ static int create_header64(DumpState *s, Error **errp)
 
     if (write_buffer(s->fd, 0, dh, size) < 0) {
         dump_error(s, "dump: failed to write disk dump header", errp);
-        ret = -1;
         goto out;
     }
 
@@ -913,7 +896,6 @@ static int create_header64(DumpState *s, Error **errp)
     if (write_buffer(s->fd, DISKDUMP_HEADER_BLOCKS *
                      block_size, kh, size) < 0) {
         dump_error(s, "dump: failed to write kdump sub header", errp);
-        ret = -1;
         goto out;
     }
 
@@ -922,15 +904,15 @@ static int create_header64(DumpState *s, Error **errp)
     s->note_buf_offset = 0;
 
     /* use s->note_buf to store notes temporarily */
-    if (write_elf64_notes(buf_write_note, s, errp) < 0) {
-        ret = -1;
+    write_elf64_notes(buf_write_note, s, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
         goto out;
     }
 
     if (write_buffer(s->fd, offset_note, s->note_buf,
                      s->note_size) < 0) {
         dump_error(s, "dump: failed to write notes", errp);
-        ret = -1;
         goto out;
     }
 
@@ -946,16 +928,19 @@ out:
     g_free(dh);
     g_free(kh);
     g_free(s->note_buf);
-
-    return ret;
 }
 
-static int write_dump_header(DumpState *s, Error **errp)
+static void write_dump_header(DumpState *s, Error **errp)
 {
+     Error *local_err = NULL;
+
     if (s->dump_info.d_class == ELFCLASS32) {
-        return create_header32(s, errp);
+        create_header32(s, &local_err);
     } else {
-        return create_header64(s, errp);
+        create_header64(s, &local_err);
+    }
+    if (local_err) {
+        error_propagate(errp, local_err);
     }
 }
 
@@ -1069,7 +1054,7 @@ static bool get_next_page(GuestPhysBlock **blockptr, uint64_t *pfnptr,
     return true;
 }
 
-static int write_dump_bitmap(DumpState *s, Error **errp)
+static void write_dump_bitmap(DumpState *s, Error **errp)
 {
     int ret = 0;
     uint64_t last_pfn, pfn;
@@ -1091,7 +1076,6 @@ static int write_dump_bitmap(DumpState *s, Error **errp)
         ret = set_dump_bitmap(last_pfn, pfn, true, dump_bitmap_buf, s);
         if (ret < 0) {
             dump_error(s, "dump: failed to set dump_bitmap", errp);
-            ret = -1;
             goto out;
         }
 
@@ -1109,7 +1093,6 @@ static int write_dump_bitmap(DumpState *s, Error **errp)
                               dump_bitmap_buf, s);
         if (ret < 0) {
             dump_error(s, "dump: failed to sync dump_bitmap", errp);
-            ret = -1;
             goto out;
         }
     }
@@ -1119,8 +1102,6 @@ static int write_dump_bitmap(DumpState *s, Error **errp)
 
 out:
     g_free(dump_bitmap_buf);
-
-    return ret;
 }
 
 static void prepare_data_cache(DataCache *data_cache, DumpState *s,
@@ -1200,7 +1181,7 @@ static inline bool is_zero_page(const uint8_t *buf, size_t page_size)
     return buffer_is_zero(buf, page_size);
 }
 
-static int write_dump_pages(DumpState *s, Error **errp)
+static void write_dump_pages(DumpState *s, Error **errp)
 {
     int ret = 0;
     DataCache page_desc, page_data;
@@ -1365,13 +1346,12 @@ out:
 #endif
 
     g_free(buf_out);
-
-    return ret;
 }
 
-static int create_kdump_vmcore(DumpState *s, Error **errp)
+static void create_kdump_vmcore(DumpState *s, Error **errp)
 {
     int ret;
+    Error *local_err = NULL;
 
     /*
      * the kdump-compressed format is:
@@ -1398,33 +1378,34 @@ static int create_kdump_vmcore(DumpState *s, Error **errp)
     ret = write_start_flat_header(s->fd);
     if (ret < 0) {
         dump_error(s, "dump: failed to write start flat header", errp);
-        return -1;
+        return;
     }
 
-    ret = write_dump_header(s, errp);
-    if (ret < 0) {
-        return -1;
+    write_dump_header(s, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        return;
     }
 
-    ret = write_dump_bitmap(s, errp);
-    if (ret < 0) {
-        return -1;
+    write_dump_bitmap(s, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        return;
     }
 
-    ret = write_dump_pages(s, errp);
-    if (ret < 0) {
-        return -1;
+    write_dump_pages(s, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        return;
     }
 
     ret = write_end_flat_header(s->fd);
     if (ret < 0) {
         dump_error(s, "dump: failed to write end flat header", errp);
-        return -1;
+        return;
     }
 
     dump_completed(s);
-
-    return 0;
 }
 
 static ram_addr_t get_start_block(DumpState *s)
@@ -1463,9 +1444,9 @@ static void get_max_mapnr(DumpState *s)
     s->max_mapnr = paddr_to_pfn(last_block->target_end);
 }
 
-static int dump_init(DumpState *s, int fd, bool has_format,
-                     DumpGuestMemoryFormat format, bool paging, bool has_filter,
-                     int64_t begin, int64_t length, Error **errp)
+static void dump_init(DumpState *s, int fd, bool has_format,
+                      DumpGuestMemoryFormat format, bool paging, bool has_filter,
+                      int64_t begin, int64_t length, Error **errp)
 {
     CPUState *cpu;
     int nr_cpus;
@@ -1570,7 +1551,7 @@ static int dump_init(DumpState *s, int fd, bool has_format,
             s->flag_compress = 0;
         }
 
-        return 0;
+        return;
     }
 
     if (s->has_filter) {
@@ -1619,11 +1600,10 @@ static int dump_init(DumpState *s, int fd, bool has_format,
         }
     }
 
-    return 0;
+    return;
 
 cleanup:
     dump_cleanup(s);
-    return -1;
 }
 
 void qmp_dump_guest_memory(bool paging, const char *file, bool has_begin,
@@ -1634,7 +1614,7 @@ void qmp_dump_guest_memory(bool paging, const char *file, bool has_begin,
     const char *p;
     int fd = -1;
     DumpState *s;
-    int ret;
+    Error *local_err = NULL;
 
     /*
      * kdump-compressed format need the whole memory dumped, so paging or
@@ -1694,19 +1674,22 @@ void qmp_dump_guest_memory(bool paging, const char *file, bool has_begin,
 
     s = g_malloc0(sizeof(DumpState));
 
-    ret = dump_init(s, fd, has_format, format, paging, has_begin,
-                    begin, length, errp);
-    if (ret < 0) {
+    dump_init(s, fd, has_format, format, paging, has_begin,
+              begin, length, &local_err);
+    if (local_err) {
         g_free(s);
+        error_propagate(errp, local_err);
         return;
     }
 
     if (has_format && format != DUMP_GUEST_MEMORY_FORMAT_ELF) {
-        create_kdump_vmcore(s, errp);
+        create_kdump_vmcore(s, &local_err);
     } else {
-        create_vmcore(s, errp);
+        create_vmcore(s, &local_err);
+    }
+    if (local_err) {
+        error_propagate(errp, local_err);
     }
-
     g_free(s);
 }
 
-- 
1.7.12.4

Re: [Qemu-devel] [PATCH v6 2/2] dump: Don't return error code when return an Error object

[Markus Armbruster]

zhanghailiang <zhang.zhanghailiang@huawei.com> writes:

> Functions shouldn't return an error code and an Error object at the same time.
> Turn all these functions that returning Error object to void.
> We also judge if a function success or fail by reference to the local_err.
>
> Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
>
> ---
>  dump.c | 313 +++++++++++++++++++++++++++++++----------------------------------
>  1 file changed, 148 insertions(+), 165 deletions(-)
>
> diff --git a/dump.c b/dump.c
> index 07d2300..a6188b3 100644
> --- a/dump.c
> +++ b/dump.c
> @@ -100,7 +100,7 @@ static int fd_write_vmcore(const void *buf, size_t size, void *opaque)
>      return 0;
>  }
>  
> -static int write_elf64_header(DumpState *s, Error **errp)
> +static void write_elf64_header(DumpState *s, Error **errp)
>  {
>      Elf64_Ehdr elf_header;
>      int ret;
> @@ -128,13 +128,10 @@ static int write_elf64_header(DumpState *s, Error **errp)
>      ret = fd_write_vmcore(&elf_header, sizeof(elf_header), s);
>      if (ret < 0) {
>          dump_error(s, "dump: failed to write elf header", errp);
> -        return -1;
>      }
> -
> -    return 0;
>  }
>  
> -static int write_elf32_header(DumpState *s, Error **errp)
> +static void write_elf32_header(DumpState *s, Error **errp)
>  {
>      Elf32_Ehdr elf_header;
>      int ret;
> @@ -162,13 +159,10 @@ static int write_elf32_header(DumpState *s, Error **errp)
>      ret = fd_write_vmcore(&elf_header, sizeof(elf_header), s);
>      if (ret < 0) {
>          dump_error(s, "dump: failed to write elf header", errp);
> -        return -1;
>      }
> -
> -    return 0;
>  }
>  
> -static int write_elf64_load(DumpState *s, MemoryMapping *memory_mapping,
> +static void write_elf64_load(DumpState *s, MemoryMapping *memory_mapping,
>                               int phdr_index, hwaddr offset,
>                               hwaddr filesz, Error **errp)
>  {
> @@ -188,15 +182,12 @@ static int write_elf64_load(DumpState *s, MemoryMapping *memory_mapping,
>      ret = fd_write_vmcore(&phdr, sizeof(Elf64_Phdr), s);
>      if (ret < 0) {
>          dump_error(s, "dump: failed to write program header table", errp);
> -        return -1;
>      }
> -
> -    return 0;
>  }
>  
> -static int write_elf32_load(DumpState *s, MemoryMapping *memory_mapping,
> -                            int phdr_index, hwaddr offset,
> -                            hwaddr filesz, Error **errp)
> +static void write_elf32_load(DumpState *s, MemoryMapping *memory_mapping,
> +                             int phdr_index, hwaddr offset,
> +                             hwaddr filesz, Error **errp)
>  {
>      Elf32_Phdr phdr;
>      int ret;
> @@ -214,13 +205,10 @@ static int write_elf32_load(DumpState *s, MemoryMapping *memory_mapping,
>      ret = fd_write_vmcore(&phdr, sizeof(Elf32_Phdr), s);
>      if (ret < 0) {
>          dump_error(s, "dump: failed to write program header table", errp);
> -        return -1;
>      }
> -
> -    return 0;
>  }
>  
> -static int write_elf64_note(DumpState *s, Error **errp)
> +static void write_elf64_note(DumpState *s, Error **errp)
>  {
>      Elf64_Phdr phdr;
>      hwaddr begin = s->memory_offset - s->note_size;
> @@ -237,10 +225,7 @@ static int write_elf64_note(DumpState *s, Error **errp)
>      ret = fd_write_vmcore(&phdr, sizeof(Elf64_Phdr), s);
>      if (ret < 0) {
>          dump_error(s, "dump: failed to write program header table", errp);
> -        return -1;
>      }
> -
> -    return 0;
>  }
>  
>  static inline int cpu_index(CPUState *cpu)
> @@ -248,8 +233,8 @@ static inline int cpu_index(CPUState *cpu)
>      return cpu->cpu_index + 1;
>  }
>  
> -static int write_elf64_notes(WriteCoreDumpFunction f, DumpState *s,
> -                             Error **errp)
> +static void write_elf64_notes(WriteCoreDumpFunction f, DumpState *s,
> +                              Error **errp)
>  {
>      CPUState *cpu;
>      int ret;
> @@ -260,7 +245,7 @@ static int write_elf64_notes(WriteCoreDumpFunction f, DumpState *s,
>          ret = cpu_write_elf64_note(f, cpu, id, s);
>          if (ret < 0) {
>              dump_error(s, "dump: failed to write elf notes", errp);
> -            return -1;
> +            return;
>          }
>      }
>  
> @@ -268,14 +253,12 @@ static int write_elf64_notes(WriteCoreDumpFunction f, DumpState *s,
>          ret = cpu_write_elf64_qemunote(f, cpu, s);
>          if (ret < 0) {
>              dump_error(s, "dump: failed to write CPU status", errp);
> -            return -1;
> +            return;
>          }
>      }
> -
> -    return 0;
>  }
>  
> -static int write_elf32_note(DumpState *s, Error **errp)
> +static void write_elf32_note(DumpState *s, Error **errp)
>  {
>      hwaddr begin = s->memory_offset - s->note_size;
>      Elf32_Phdr phdr;
> @@ -292,14 +275,11 @@ static int write_elf32_note(DumpState *s, Error **errp)
>      ret = fd_write_vmcore(&phdr, sizeof(Elf32_Phdr), s);
>      if (ret < 0) {
>          dump_error(s, "dump: failed to write program header table", errp);
> -        return -1;
>      }
> -
> -    return 0;
>  }
>  
> -static int write_elf32_notes(WriteCoreDumpFunction f, DumpState *s,
> -                             Error **errp)
> +static void write_elf32_notes(WriteCoreDumpFunction f, DumpState *s,
> +                              Error **errp)
>  {
>      CPUState *cpu;
>      int ret;
> @@ -310,7 +290,7 @@ static int write_elf32_notes(WriteCoreDumpFunction f, DumpState *s,
>          ret = cpu_write_elf32_note(f, cpu, id, s);
>          if (ret < 0) {
>              dump_error(s, "dump: failed to write elf notes", errp);
> -            return -1;
> +            return;
>          }
>      }
>  
> @@ -318,14 +298,12 @@ static int write_elf32_notes(WriteCoreDumpFunction f, DumpState *s,
>          ret = cpu_write_elf32_qemunote(f, cpu, s);
>          if (ret < 0) {
>              dump_error(s, "dump: failed to write CPU status", errp);
> -            return -1;
> +            return;
>          }
>      }
> -
> -    return 0;
>  }
>  
> -static int write_elf_section(DumpState *s, int type, Error **errp)
> +static void write_elf_section(DumpState *s, int type, Error **errp)
>  {
>      Elf32_Shdr shdr32;
>      Elf64_Shdr shdr64;
> @@ -348,49 +326,45 @@ static int write_elf_section(DumpState *s, int type, Error **errp)
>      ret = fd_write_vmcore(&shdr, shdr_size, s);
>      if (ret < 0) {
>          dump_error(s, "dump: failed to write section header table", errp);
> -        return -1;
> +        return;
>      }
> -
> -    return 0;
>  }
>  
> -static int write_data(DumpState *s, void *buf, int length, Error **errp)
> +static void write_data(DumpState *s, void *buf, int length, Error **errp)
>  {
>      int ret;
>  
>      ret = fd_write_vmcore(buf, length, s);
>      if (ret < 0) {
>          dump_error(s, "dump: failed to save memory", errp);
> -        return -1;
> +        return;
>      }
> -
> -    return 0;
>  }
>  
>  /* write the memroy to vmcore. 1 page per I/O. */
> -static int write_memory(DumpState *s, GuestPhysBlock *block, ram_addr_t start,
> -                        int64_t size, Error **errp)
> +static void write_memory(DumpState *s, GuestPhysBlock *block, ram_addr_t start,
> +                         int64_t size, Error **errp)
>  {
>      int64_t i;
> -    int ret;
> +    Error *local_err = NULL;
>  
>      for (i = 0; i < size / TARGET_PAGE_SIZE; i++) {
> -        ret = write_data(s, block->host_addr + start + i * TARGET_PAGE_SIZE,
> -                         TARGET_PAGE_SIZE, errp);
> -        if (ret < 0) {
> -            return ret;
> +        write_data(s, block->host_addr + start + i * TARGET_PAGE_SIZE,
> +                   TARGET_PAGE_SIZE, &local_err);
> +        if (local_err) {
> +            error_propagate(errp, local_err);
> +            return;
>          }
>      }
>  
>      if ((size % TARGET_PAGE_SIZE) != 0) {
> -        ret = write_data(s, block->host_addr + start + i * TARGET_PAGE_SIZE,
> -                         size % TARGET_PAGE_SIZE, errp);
> -        if (ret < 0) {
> -            return ret;
> +        write_data(s, block->host_addr + start + i * TARGET_PAGE_SIZE,
> +                   size % TARGET_PAGE_SIZE, &local_err);
> +        if (local_err) {
> +            error_propagate(errp, local_err);
> +            return;
>          }
>      }
> -
> -    return 0;
>  }
>  
>  /* get the memory's offset and size in the vmcore */
> @@ -455,13 +429,13 @@ static void get_offset_range(hwaddr phys_addr,
>      }
>  }
>  
> -static int write_elf_loads(DumpState *s, Error **errp)
> +static void write_elf_loads(DumpState *s, Error **errp)
>  {
>      hwaddr offset, filesz;
>      MemoryMapping *memory_mapping;
>      uint32_t phdr_index = 1;
> -    int ret;
>      uint32_t max_index;
> +    Error *local_err = NULL;
>  
>      if (s->have_section) {
>          max_index = s->sh_info;
> @@ -474,29 +448,28 @@ static int write_elf_loads(DumpState *s, Error **errp)
>                           memory_mapping->length,
>                           s, &offset, &filesz);
>          if (s->dump_info.d_class == ELFCLASS64) {
> -            ret = write_elf64_load(s, memory_mapping, phdr_index++, offset,
> -                                   filesz, errp);
> +            write_elf64_load(s, memory_mapping, phdr_index++, offset,
> +                             filesz, &local_err);
>          } else {
> -            ret = write_elf32_load(s, memory_mapping, phdr_index++, offset,
> -                                   filesz, errp);
> +            write_elf32_load(s, memory_mapping, phdr_index++, offset,
> +                             filesz, &local_err);
>          }
>  
> -        if (ret < 0) {
> -            return -1;
> +        if (local_err) {
> +            error_propagate(errp, local_err);
> +            return;
>          }
>  
>          if (phdr_index >= max_index) {
>              break;
>          }
>      }
> -
> -    return 0;
>  }
>  
>  /* write elf header, PT_NOTE and elf note to vmcore. */
> -static int dump_begin(DumpState *s, Error **errp)
> +static void dump_begin(DumpState *s, Error **errp)
>  {
> -    int ret;
> +    Error *local_err = NULL;
>  
>      /*
>       * the vmcore's format is:
> @@ -524,62 +497,76 @@ static int dump_begin(DumpState *s, Error **errp)
>  
>      /* write elf header to vmcore */
>      if (s->dump_info.d_class == ELFCLASS64) {
> -        ret = write_elf64_header(s, errp);
> +        write_elf64_header(s, &local_err);
>      } else {
> -        ret = write_elf32_header(s, errp);
> +        write_elf32_header(s, &local_err);
>      }
> -    if (ret < 0) {
> -        return -1;
> +    if (local_err) {
> +        error_propagate(errp, local_err);
> +        return;
>      }
>  
>      if (s->dump_info.d_class == ELFCLASS64) {
>          /* write PT_NOTE to vmcore */
> -        if (write_elf64_note(s, errp) < 0) {
> -            return -1;
> +        write_elf64_note(s, &local_err);
> +        if (local_err) {
> +            error_propagate(errp, local_err);
> +            return;
>          }
>  
>          /* write all PT_LOAD to vmcore */
> -        if (write_elf_loads(s, errp) < 0) {
> -            return -1;
> +        write_elf_loads(s, &local_err);
> +        if (local_err) {
> +            error_propagate(errp, local_err);
> +            return;
>          }
>  
>          /* write section to vmcore */
>          if (s->have_section) {
> -            if (write_elf_section(s, 1, errp) < 0) {
> -                return -1;
> +            write_elf_section(s, 1, &local_err);
> +            if (local_err) {
> +                error_propagate(errp, local_err);
> +                return;
>              }
>          }
>  
>          /* write notes to vmcore */
> -        if (write_elf64_notes(fd_write_vmcore, s, errp) < 0) {
> -            return -1;
> +        write_elf64_notes(fd_write_vmcore, s, &local_err);
> +        if (local_err) {
> +            error_propagate(errp, local_err);
> +            return;
>          }
> -
>      } else {
>          /* write PT_NOTE to vmcore */
> -        if (write_elf32_note(s, errp) < 0) {
> -            return -1;
> +        write_elf32_note(s, &local_err);
> +        if (local_err) {
> +            error_propagate(errp, local_err);
> +            return;
>          }
>  
>          /* write all PT_LOAD to vmcore */
> -        if (write_elf_loads(s, errp) < 0) {
> -            return -1;
> +        write_elf_loads(s, &local_err);
> +        if (local_err) {
> +            error_propagate(errp, local_err);
> +            return;
>          }
>  
>          /* write section to vmcore */
>          if (s->have_section) {
> -            if (write_elf_section(s, 0, errp) < 0) {
> -                return -1;
> +            write_elf_section(s, 0, &local_err);
> +            if (local_err) {
> +                error_propagate(errp, local_err);
> +                return;
>              }
>          }
>  
>          /* write notes to vmcore */
> -        if (write_elf32_notes(fd_write_vmcore, s, errp) < 0) {
> -            return -1;
> +        write_elf32_notes(fd_write_vmcore, s, &local_err);
> +        if (local_err) {
> +            error_propagate(errp, local_err);
> +            return;
>          }
>      }
> -
> -    return 0;
>  }
>  
>  /* write PT_LOAD to vmcore */
   static int dump_completed(DumpState *s)
   {
       dump_cleanup(s);
       return 0;
   }

I doubt this comment is accurate.  Outside the scope of this patch.

> @@ -617,11 +604,12 @@ static int get_next_block(DumpState *s, GuestPhysBlock *block)
>  }
>  
>  /* write all memory to vmcore */
> -static int dump_iterate(DumpState *s, Error **errp)
> +static void dump_iterate(DumpState *s, Error **errp)
>  {
>      GuestPhysBlock *block;
>      int64_t size;
>      int ret;
> +    Error *local_err = NULL;
>  
>      while (1) {
>          block = s->next_block;
> @@ -633,34 +621,35 @@ static int dump_iterate(DumpState *s, Error **errp)
>                  size -= block->target_end - (s->begin + s->length);
>              }
>          }
> -        ret = write_memory(s, block, s->start, size, errp);
> -        if (ret == -1) {
> -            return ret;
> +        write_memory(s, block, s->start, size, &local_err);
> +        if (local_err) {
> +            error_propagate(errp, local_err);
> +            return;
>          }
>  
>          ret = get_next_block(s, block);
>          if (ret == 1) {
>              dump_completed(s);
> -            return 0;
>          }
>      }
>  }
>  
> -static int create_vmcore(DumpState *s, Error **errp)
> +static void create_vmcore(DumpState *s, Error **errp)
>  {
> -    int ret;
> +    Error *local_err = NULL;
>  
> -    ret = dump_begin(s, errp);
> -    if (ret < 0) {
> -        return -1;
> +    dump_begin(s, &local_err);
> +    if (local_err) {
> +        error_propagate(errp, local_err);
> +        return;
>      }
>  
> -    ret = dump_iterate(s, errp);
> -    if (ret < 0) {
> -        return -1;
> +    dump_iterate(s, &local_err);
> +    if (local_err) {
> +        error_propagate(errp, local_err);
> +        return;
>      }
>  

Please drop this blank line, like you do elsewhere.

> -    return 0;
>  }
>  

You need local_err when you want to examine the error.  You do after
dump_begin(), because you want to return early on error.  You don't
after dump_iterate().  There, you could simply call

    dump_iterate(s, errp);

and be done with it.  Your choice.

>  static int write_start_flat_header(int fd)
> @@ -741,9 +730,8 @@ static int buf_write_note(const void *buf, size_t size, void *opaque)
>  }
>  
>  /* write common header, sub header and elf note to vmcore */
> -static int create_header32(DumpState *s, Error **errp)
> +static void create_header32(DumpState *s, Error **errp)
>  {
> -    int ret = 0;
>      DiskDumpHeader32 *dh = NULL;
>      KdumpSubHeader32 *kh = NULL;
>      size_t size;
> @@ -752,6 +740,7 @@ static int create_header32(DumpState *s, Error **errp)
>      uint32_t bitmap_blocks;
>      uint32_t status = 0;
>      uint64_t offset_note;
> +    Error *local_err = NULL;
>  
>      /* write common header, the version of kdump-compressed format is 6th */
>      size = sizeof(DiskDumpHeader32);
> @@ -788,7 +777,6 @@ static int create_header32(DumpState *s, Error **errp)
>  
>      if (write_buffer(s->fd, 0, dh, size) < 0) {
>          dump_error(s, "dump: failed to write disk dump header", errp);
> -        ret = -1;
>          goto out;
>      }
>  
> @@ -808,7 +796,6 @@ static int create_header32(DumpState *s, Error **errp)
>      if (write_buffer(s->fd, DISKDUMP_HEADER_BLOCKS *
>                       block_size, kh, size) < 0) {
>          dump_error(s, "dump: failed to write kdump sub header", errp);
> -        ret = -1;
>          goto out;
>      }
>  
> @@ -817,15 +804,14 @@ static int create_header32(DumpState *s, Error **errp)
>      s->note_buf_offset = 0;
>  
>      /* use s->note_buf to store notes temporarily */
> -    if (write_elf32_notes(buf_write_note, s, errp) < 0) {
> -        ret = -1;
> +    write_elf32_notes(buf_write_note, s, &local_err);
> +    if (local_err) {
> +        error_propagate(errp, local_err);
>          goto out;
>      }
> -
>      if (write_buffer(s->fd, offset_note, s->note_buf,
>                       s->note_size) < 0) {
>          dump_error(s, "dump: failed to write notes", errp);
> -        ret = -1;
>          goto out;
>      }
>  
> @@ -841,14 +827,11 @@ out:
>      g_free(dh);
>      g_free(kh);
>      g_free(s->note_buf);
> -
> -    return ret;
>  }
>  
>  /* write common header, sub header and elf note to vmcore */
> -static int create_header64(DumpState *s, Error **errp)
> +static void create_header64(DumpState *s, Error **errp)
>  {
> -    int ret = 0;
>      DiskDumpHeader64 *dh = NULL;
>      KdumpSubHeader64 *kh = NULL;
>      size_t size;
> @@ -857,6 +840,7 @@ static int create_header64(DumpState *s, Error **errp)
>      uint32_t bitmap_blocks;
>      uint32_t status = 0;
>      uint64_t offset_note;
> +    Error *local_err = NULL;
>  
>      /* write common header, the version of kdump-compressed format is 6th */
>      size = sizeof(DiskDumpHeader64);
> @@ -893,7 +877,6 @@ static int create_header64(DumpState *s, Error **errp)
>  
>      if (write_buffer(s->fd, 0, dh, size) < 0) {
>          dump_error(s, "dump: failed to write disk dump header", errp);
> -        ret = -1;
>          goto out;
>      }
>  
> @@ -913,7 +896,6 @@ static int create_header64(DumpState *s, Error **errp)
>      if (write_buffer(s->fd, DISKDUMP_HEADER_BLOCKS *
>                       block_size, kh, size) < 0) {
>          dump_error(s, "dump: failed to write kdump sub header", errp);
> -        ret = -1;
>          goto out;
>      }
>  
> @@ -922,15 +904,15 @@ static int create_header64(DumpState *s, Error **errp)
>      s->note_buf_offset = 0;
>  
>      /* use s->note_buf to store notes temporarily */
> -    if (write_elf64_notes(buf_write_note, s, errp) < 0) {
> -        ret = -1;
> +    write_elf64_notes(buf_write_note, s, &local_err);
> +    if (local_err) {
> +        error_propagate(errp, local_err);
>          goto out;
>      }
>  
>      if (write_buffer(s->fd, offset_note, s->note_buf,
>                       s->note_size) < 0) {
>          dump_error(s, "dump: failed to write notes", errp);
> -        ret = -1;
>          goto out;
>      }
>  
> @@ -946,16 +928,19 @@ out:
>      g_free(dh);
>      g_free(kh);
>      g_free(s->note_buf);
> -
> -    return ret;
>  }
>  
> -static int write_dump_header(DumpState *s, Error **errp)
> +static void write_dump_header(DumpState *s, Error **errp)
>  {
> +     Error *local_err = NULL;
> +
>      if (s->dump_info.d_class == ELFCLASS32) {
> -        return create_header32(s, errp);
> +        create_header32(s, &local_err);
>      } else {
> -        return create_header64(s, errp);
> +        create_header64(s, &local_err);
> +    }
> +    if (local_err) {
> +        error_propagate(errp, local_err);
>      }
>  }
>  
> @@ -1069,7 +1054,7 @@ static bool get_next_page(GuestPhysBlock **blockptr, uint64_t *pfnptr,
>      return true;
>  }
>  
> -static int write_dump_bitmap(DumpState *s, Error **errp)
> +static void write_dump_bitmap(DumpState *s, Error **errp)
>  {
>      int ret = 0;
>      uint64_t last_pfn, pfn;
> @@ -1091,7 +1076,6 @@ static int write_dump_bitmap(DumpState *s, Error **errp)
>          ret = set_dump_bitmap(last_pfn, pfn, true, dump_bitmap_buf, s);
>          if (ret < 0) {
>              dump_error(s, "dump: failed to set dump_bitmap", errp);
> -            ret = -1;
>              goto out;
>          }
>  
> @@ -1109,7 +1093,6 @@ static int write_dump_bitmap(DumpState *s, Error **errp)
>                                dump_bitmap_buf, s);
>          if (ret < 0) {
>              dump_error(s, "dump: failed to sync dump_bitmap", errp);
> -            ret = -1;
>              goto out;
>          }
>      }
> @@ -1119,8 +1102,6 @@ static int write_dump_bitmap(DumpState *s, Error **errp)
>  
>  out:
>      g_free(dump_bitmap_buf);
> -
> -    return ret;
>  }
>  
>  static void prepare_data_cache(DataCache *data_cache, DumpState *s,
> @@ -1200,7 +1181,7 @@ static inline bool is_zero_page(const uint8_t *buf, size_t page_size)
>      return buffer_is_zero(buf, page_size);
>  }
>  
> -static int write_dump_pages(DumpState *s, Error **errp)
> +static void write_dump_pages(DumpState *s, Error **errp)
>  {
>      int ret = 0;
>      DataCache page_desc, page_data;
> @@ -1365,13 +1346,12 @@ out:
>  #endif
>  
>      g_free(buf_out);
> -
> -    return ret;
>  }
>  
> -static int create_kdump_vmcore(DumpState *s, Error **errp)
> +static void create_kdump_vmcore(DumpState *s, Error **errp)
>  {
>      int ret;
> +    Error *local_err = NULL;
>  
>      /*
>       * the kdump-compressed format is:
> @@ -1398,33 +1378,34 @@ static int create_kdump_vmcore(DumpState *s, Error **errp)
>      ret = write_start_flat_header(s->fd);
>      if (ret < 0) {
>          dump_error(s, "dump: failed to write start flat header", errp);
> -        return -1;
> +        return;
>      }
>  
> -    ret = write_dump_header(s, errp);
> -    if (ret < 0) {
> -        return -1;
> +    write_dump_header(s, &local_err);
> +    if (local_err) {
> +        error_propagate(errp, local_err);
> +        return;
>      }
>  
> -    ret = write_dump_bitmap(s, errp);
> -    if (ret < 0) {
> -        return -1;
> +    write_dump_bitmap(s, &local_err);
> +    if (local_err) {
> +        error_propagate(errp, local_err);
> +        return;
>      }
>  
> -    ret = write_dump_pages(s, errp);
> -    if (ret < 0) {
> -        return -1;
> +    write_dump_pages(s, &local_err);
> +    if (local_err) {
> +        error_propagate(errp, local_err);
> +        return;
>      }
>  
>      ret = write_end_flat_header(s->fd);
>      if (ret < 0) {
>          dump_error(s, "dump: failed to write end flat header", errp);
> -        return -1;
> +        return;
>      }
>  
>      dump_completed(s);
> -
> -    return 0;
>  }
>  
>  static ram_addr_t get_start_block(DumpState *s)
> @@ -1463,9 +1444,9 @@ static void get_max_mapnr(DumpState *s)
>      s->max_mapnr = paddr_to_pfn(last_block->target_end);
>  }
>  
> -static int dump_init(DumpState *s, int fd, bool has_format,
> -                     DumpGuestMemoryFormat format, bool paging, bool has_filter,
> -                     int64_t begin, int64_t length, Error **errp)
> +static void dump_init(DumpState *s, int fd, bool has_format,
> +                      DumpGuestMemoryFormat format, bool paging, bool has_filter,
> +                      int64_t begin, int64_t length, Error **errp)
>  {
>      CPUState *cpu;
>      int nr_cpus;
> @@ -1570,7 +1551,7 @@ static int dump_init(DumpState *s, int fd, bool has_format,
>              s->flag_compress = 0;
>          }
>  
> -        return 0;
> +        return;
>      }
>  
>      if (s->has_filter) {
> @@ -1619,11 +1600,10 @@ static int dump_init(DumpState *s, int fd, bool has_format,
>          }
>      }
>  
> -    return 0;
> +    return;
>  
>  cleanup:
>      dump_cleanup(s);
> -    return -1;
>  }
>  
>  void qmp_dump_guest_memory(bool paging, const char *file, bool has_begin,
> @@ -1634,7 +1614,7 @@ void qmp_dump_guest_memory(bool paging, const char *file, bool has_begin,
>      const char *p;
>      int fd = -1;
>      DumpState *s;
> -    int ret;
> +    Error *local_err = NULL;
>  
>      /*
>       * kdump-compressed format need the whole memory dumped, so paging or
> @@ -1694,19 +1674,22 @@ void qmp_dump_guest_memory(bool paging, const char *file, bool has_begin,
>  
>      s = g_malloc0(sizeof(DumpState));
>  
> -    ret = dump_init(s, fd, has_format, format, paging, has_begin,
> -                    begin, length, errp);
> -    if (ret < 0) {
> +    dump_init(s, fd, has_format, format, paging, has_begin,
> +              begin, length, &local_err);
> +    if (local_err) {
>          g_free(s);
> +        error_propagate(errp, local_err);
>          return;
>      }
>  
>      if (has_format && format != DUMP_GUEST_MEMORY_FORMAT_ELF) {
> -        create_kdump_vmcore(s, errp);
> +        create_kdump_vmcore(s, &local_err);
>      } else {
> -        create_vmcore(s, errp);
> +        create_vmcore(s, &local_err);
> +    }
> +    if (local_err) {
> +        error_propagate(errp, local_err);
>      }
> -
>      g_free(s);
>  }

Another case where local_err isn't needed.  You could simplify to just

    if (has_format && format != DUMP_GUEST_MEMORY_FORMAT_ELF) {
        create_kdump_vmcore(s, errp);
    } else {
        create_vmcore(s, errp);
    }
    g_free(s);


This patch illustrates why I dislike void functions with an Error **
parameter: lots of busy-work with error_propagate().  But others feel
it's what we should do.  *shrug*

Patch looks correct to me on a glance.  I'm leaving real review to the
folks who think it's what we should do.

Re: [Qemu-devel] [PATCH v6 2/2] dump: Don't return error code when return an Error object

[zhanghailiang]

On 2014/9/29 16:06, Markus Armbruster wrote:
> zhanghailiang <zhang.zhanghailiang@huawei.com> writes:
>
>> Functions shouldn't return an error code and an Error object at the same time.
>> Turn all these functions that returning Error object to void.
>> We also judge if a function success or fail by reference to the local_err.
>>
>> Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
>>
>> ---
>>   dump.c | 313 +++++++++++++++++++++++++++++++----------------------------------
>>   1 file changed, 148 insertions(+), 165 deletions(-)
>>
>> diff --git a/dump.c b/dump.c
>> index 07d2300..a6188b3 100644
>> --- a/dump.c
>> +++ b/dump.c
>> @@ -100,7 +100,7 @@ static int fd_write_vmcore(const void *buf, size_t size, void *opaque)
>>       return 0;
>>   }
>>
>> -static int write_elf64_header(DumpState *s, Error **errp)
>> +static void write_elf64_header(DumpState *s, Error **errp)
>>   {
>>       Elf64_Ehdr elf_header;
>>       int ret;
>> @@ -128,13 +128,10 @@ static int write_elf64_header(DumpState *s, Error **errp)
>>       ret = fd_write_vmcore(&elf_header, sizeof(elf_header), s);
>>       if (ret < 0) {
>>           dump_error(s, "dump: failed to write elf header", errp);
>> -        return -1;
>>       }
>> -
>> -    return 0;
>>   }
>>
>> -static int write_elf32_header(DumpState *s, Error **errp)
>> +static void write_elf32_header(DumpState *s, Error **errp)
>>   {
>>       Elf32_Ehdr elf_header;
>>       int ret;
>> @@ -162,13 +159,10 @@ static int write_elf32_header(DumpState *s, Error **errp)
>>       ret = fd_write_vmcore(&elf_header, sizeof(elf_header), s);
>>       if (ret < 0) {
>>           dump_error(s, "dump: failed to write elf header", errp);
>> -        return -1;
>>       }
>> -
>> -    return 0;
>>   }
>>
>> -static int write_elf64_load(DumpState *s, MemoryMapping *memory_mapping,
>> +static void write_elf64_load(DumpState *s, MemoryMapping *memory_mapping,
>>                                int phdr_index, hwaddr offset,
>>                                hwaddr filesz, Error **errp)
>>   {
>> @@ -188,15 +182,12 @@ static int write_elf64_load(DumpState *s, MemoryMapping *memory_mapping,
>>       ret = fd_write_vmcore(&phdr, sizeof(Elf64_Phdr), s);
>>       if (ret < 0) {
>>           dump_error(s, "dump: failed to write program header table", errp);
>> -        return -1;
>>       }
>> -
>> -    return 0;
>>   }
>>
>> -static int write_elf32_load(DumpState *s, MemoryMapping *memory_mapping,
>> -                            int phdr_index, hwaddr offset,
>> -                            hwaddr filesz, Error **errp)
>> +static void write_elf32_load(DumpState *s, MemoryMapping *memory_mapping,
>> +                             int phdr_index, hwaddr offset,
>> +                             hwaddr filesz, Error **errp)
>>   {
>>       Elf32_Phdr phdr;
>>       int ret;
>> @@ -214,13 +205,10 @@ static int write_elf32_load(DumpState *s, MemoryMapping *memory_mapping,
>>       ret = fd_write_vmcore(&phdr, sizeof(Elf32_Phdr), s);
>>       if (ret < 0) {
>>           dump_error(s, "dump: failed to write program header table", errp);
>> -        return -1;
>>       }
>> -
>> -    return 0;
>>   }
>>
>> -static int write_elf64_note(DumpState *s, Error **errp)
>> +static void write_elf64_note(DumpState *s, Error **errp)
>>   {
>>       Elf64_Phdr phdr;
>>       hwaddr begin = s->memory_offset - s->note_size;
>> @@ -237,10 +225,7 @@ static int write_elf64_note(DumpState *s, Error **errp)
>>       ret = fd_write_vmcore(&phdr, sizeof(Elf64_Phdr), s);
>>       if (ret < 0) {
>>           dump_error(s, "dump: failed to write program header table", errp);
>> -        return -1;
>>       }
>> -
>> -    return 0;
>>   }
>>
>>   static inline int cpu_index(CPUState *cpu)
>> @@ -248,8 +233,8 @@ static inline int cpu_index(CPUState *cpu)
>>       return cpu->cpu_index + 1;
>>   }
>>
>> -static int write_elf64_notes(WriteCoreDumpFunction f, DumpState *s,
>> -                             Error **errp)
>> +static void write_elf64_notes(WriteCoreDumpFunction f, DumpState *s,
>> +                              Error **errp)
>>   {
>>       CPUState *cpu;
>>       int ret;
>> @@ -260,7 +245,7 @@ static int write_elf64_notes(WriteCoreDumpFunction f, DumpState *s,
>>           ret = cpu_write_elf64_note(f, cpu, id, s);
>>           if (ret < 0) {
>>               dump_error(s, "dump: failed to write elf notes", errp);
>> -            return -1;
>> +            return;
>>           }
>>       }
>>
>> @@ -268,14 +253,12 @@ static int write_elf64_notes(WriteCoreDumpFunction f, DumpState *s,
>>           ret = cpu_write_elf64_qemunote(f, cpu, s);
>>           if (ret < 0) {
>>               dump_error(s, "dump: failed to write CPU status", errp);
>> -            return -1;
>> +            return;
>>           }
>>       }
>> -
>> -    return 0;
>>   }
>>
>> -static int write_elf32_note(DumpState *s, Error **errp)
>> +static void write_elf32_note(DumpState *s, Error **errp)
>>   {
>>       hwaddr begin = s->memory_offset - s->note_size;
>>       Elf32_Phdr phdr;
>> @@ -292,14 +275,11 @@ static int write_elf32_note(DumpState *s, Error **errp)
>>       ret = fd_write_vmcore(&phdr, sizeof(Elf32_Phdr), s);
>>       if (ret < 0) {
>>           dump_error(s, "dump: failed to write program header table", errp);
>> -        return -1;
>>       }
>> -
>> -    return 0;
>>   }
>>
>> -static int write_elf32_notes(WriteCoreDumpFunction f, DumpState *s,
>> -                             Error **errp)
>> +static void write_elf32_notes(WriteCoreDumpFunction f, DumpState *s,
>> +                              Error **errp)
>>   {
>>       CPUState *cpu;
>>       int ret;
>> @@ -310,7 +290,7 @@ static int write_elf32_notes(WriteCoreDumpFunction f, DumpState *s,
>>           ret = cpu_write_elf32_note(f, cpu, id, s);
>>           if (ret < 0) {
>>               dump_error(s, "dump: failed to write elf notes", errp);
>> -            return -1;
>> +            return;
>>           }
>>       }
>>
>> @@ -318,14 +298,12 @@ static int write_elf32_notes(WriteCoreDumpFunction f, DumpState *s,
>>           ret = cpu_write_elf32_qemunote(f, cpu, s);
>>           if (ret < 0) {
>>               dump_error(s, "dump: failed to write CPU status", errp);
>> -            return -1;
>> +            return;
>>           }
>>       }
>> -
>> -    return 0;
>>   }
>>
>> -static int write_elf_section(DumpState *s, int type, Error **errp)
>> +static void write_elf_section(DumpState *s, int type, Error **errp)
>>   {
>>       Elf32_Shdr shdr32;
>>       Elf64_Shdr shdr64;
>> @@ -348,49 +326,45 @@ static int write_elf_section(DumpState *s, int type, Error **errp)
>>       ret = fd_write_vmcore(&shdr, shdr_size, s);
>>       if (ret < 0) {
>>           dump_error(s, "dump: failed to write section header table", errp);
>> -        return -1;
>> +        return;
>>       }
>> -
>> -    return 0;
>>   }
>>
>> -static int write_data(DumpState *s, void *buf, int length, Error **errp)
>> +static void write_data(DumpState *s, void *buf, int length, Error **errp)
>>   {
>>       int ret;
>>
>>       ret = fd_write_vmcore(buf, length, s);
>>       if (ret < 0) {
>>           dump_error(s, "dump: failed to save memory", errp);
>> -        return -1;
>> +        return;
>>       }
>> -
>> -    return 0;
>>   }
>>
>>   /* write the memroy to vmcore. 1 page per I/O. */
>> -static int write_memory(DumpState *s, GuestPhysBlock *block, ram_addr_t start,
>> -                        int64_t size, Error **errp)
>> +static void write_memory(DumpState *s, GuestPhysBlock *block, ram_addr_t start,
>> +                         int64_t size, Error **errp)
>>   {
>>       int64_t i;
>> -    int ret;
>> +    Error *local_err = NULL;
>>
>>       for (i = 0; i < size / TARGET_PAGE_SIZE; i++) {
>> -        ret = write_data(s, block->host_addr + start + i * TARGET_PAGE_SIZE,
>> -                         TARGET_PAGE_SIZE, errp);
>> -        if (ret < 0) {
>> -            return ret;
>> +        write_data(s, block->host_addr + start + i * TARGET_PAGE_SIZE,
>> +                   TARGET_PAGE_SIZE, &local_err);
>> +        if (local_err) {
>> +            error_propagate(errp, local_err);
>> +            return;
>>           }
>>       }
>>
>>       if ((size % TARGET_PAGE_SIZE) != 0) {
>> -        ret = write_data(s, block->host_addr + start + i * TARGET_PAGE_SIZE,
>> -                         size % TARGET_PAGE_SIZE, errp);
>> -        if (ret < 0) {
>> -            return ret;
>> +        write_data(s, block->host_addr + start + i * TARGET_PAGE_SIZE,
>> +                   size % TARGET_PAGE_SIZE, &local_err);
>> +        if (local_err) {
>> +            error_propagate(errp, local_err);
>> +            return;
>>           }
>>       }
>> -
>> -    return 0;
>>   }
>>
>>   /* get the memory's offset and size in the vmcore */
>> @@ -455,13 +429,13 @@ static void get_offset_range(hwaddr phys_addr,
>>       }
>>   }
>>
>> -static int write_elf_loads(DumpState *s, Error **errp)
>> +static void write_elf_loads(DumpState *s, Error **errp)
>>   {
>>       hwaddr offset, filesz;
>>       MemoryMapping *memory_mapping;
>>       uint32_t phdr_index = 1;
>> -    int ret;
>>       uint32_t max_index;
>> +    Error *local_err = NULL;
>>
>>       if (s->have_section) {
>>           max_index = s->sh_info;
>> @@ -474,29 +448,28 @@ static int write_elf_loads(DumpState *s, Error **errp)
>>                            memory_mapping->length,
>>                            s, &offset, &filesz);
>>           if (s->dump_info.d_class == ELFCLASS64) {
>> -            ret = write_elf64_load(s, memory_mapping, phdr_index++, offset,
>> -                                   filesz, errp);
>> +            write_elf64_load(s, memory_mapping, phdr_index++, offset,
>> +                             filesz, &local_err);
>>           } else {
>> -            ret = write_elf32_load(s, memory_mapping, phdr_index++, offset,
>> -                                   filesz, errp);
>> +            write_elf32_load(s, memory_mapping, phdr_index++, offset,
>> +                             filesz, &local_err);
>>           }
>>
>> -        if (ret < 0) {
>> -            return -1;
>> +        if (local_err) {
>> +            error_propagate(errp, local_err);
>> +            return;
>>           }
>>
>>           if (phdr_index >= max_index) {
>>               break;
>>           }
>>       }
>> -
>> -    return 0;
>>   }
>>
>>   /* write elf header, PT_NOTE and elf note to vmcore. */
>> -static int dump_begin(DumpState *s, Error **errp)
>> +static void dump_begin(DumpState *s, Error **errp)
>>   {
>> -    int ret;
>> +    Error *local_err = NULL;
>>
>>       /*
>>        * the vmcore's format is:
>> @@ -524,62 +497,76 @@ static int dump_begin(DumpState *s, Error **errp)
>>
>>       /* write elf header to vmcore */
>>       if (s->dump_info.d_class == ELFCLASS64) {
>> -        ret = write_elf64_header(s, errp);
>> +        write_elf64_header(s, &local_err);
>>       } else {
>> -        ret = write_elf32_header(s, errp);
>> +        write_elf32_header(s, &local_err);
>>       }
>> -    if (ret < 0) {
>> -        return -1;
>> +    if (local_err) {
>> +        error_propagate(errp, local_err);
>> +        return;
>>       }
>>
>>       if (s->dump_info.d_class == ELFCLASS64) {
>>           /* write PT_NOTE to vmcore */
>> -        if (write_elf64_note(s, errp) < 0) {
>> -            return -1;
>> +        write_elf64_note(s, &local_err);
>> +        if (local_err) {
>> +            error_propagate(errp, local_err);
>> +            return;
>>           }
>>
>>           /* write all PT_LOAD to vmcore */
>> -        if (write_elf_loads(s, errp) < 0) {
>> -            return -1;
>> +        write_elf_loads(s, &local_err);
>> +        if (local_err) {
>> +            error_propagate(errp, local_err);
>> +            return;
>>           }
>>
>>           /* write section to vmcore */
>>           if (s->have_section) {
>> -            if (write_elf_section(s, 1, errp) < 0) {
>> -                return -1;
>> +            write_elf_section(s, 1, &local_err);
>> +            if (local_err) {
>> +                error_propagate(errp, local_err);
>> +                return;
>>               }
>>           }
>>
>>           /* write notes to vmcore */
>> -        if (write_elf64_notes(fd_write_vmcore, s, errp) < 0) {
>> -            return -1;
>> +        write_elf64_notes(fd_write_vmcore, s, &local_err);
>> +        if (local_err) {
>> +            error_propagate(errp, local_err);
>> +            return;
>>           }
>> -
>>       } else {
>>           /* write PT_NOTE to vmcore */
>> -        if (write_elf32_note(s, errp) < 0) {
>> -            return -1;
>> +        write_elf32_note(s, &local_err);
>> +        if (local_err) {
>> +            error_propagate(errp, local_err);
>> +            return;
>>           }
>>
>>           /* write all PT_LOAD to vmcore */
>> -        if (write_elf_loads(s, errp) < 0) {
>> -            return -1;
>> +        write_elf_loads(s, &local_err);
>> +        if (local_err) {
>> +            error_propagate(errp, local_err);
>> +            return;
>>           }
>>
>>           /* write section to vmcore */
>>           if (s->have_section) {
>> -            if (write_elf_section(s, 0, errp) < 0) {
>> -                return -1;
>> +            write_elf_section(s, 0, &local_err);
>> +            if (local_err) {
>> +                error_propagate(errp, local_err);
>> +                return;
>>               }
>>           }
>>
>>           /* write notes to vmcore */
>> -        if (write_elf32_notes(fd_write_vmcore, s, errp) < 0) {
>> -            return -1;
>> +        write_elf32_notes(fd_write_vmcore, s, &local_err);
>> +        if (local_err) {
>> +            error_propagate(errp, local_err);
>> +            return;
>>           }
>>       }
>> -
>> -    return 0;
>>   }
>>
>>   /* write PT_LOAD to vmcore */
>     static int dump_completed(DumpState *s)
>     {
>         dump_cleanup(s);
>         return 0;
>     }
>
> I doubt this comment is accurate.  Outside the scope of this patch.
>

Er, i will clean it and also change this function to void in this patch. Thanks.

>> @@ -617,11 +604,12 @@ static int get_next_block(DumpState *s, GuestPhysBlock *block)
>>   }
>>
>>   /* write all memory to vmcore */
>> -static int dump_iterate(DumpState *s, Error **errp)
>> +static void dump_iterate(DumpState *s, Error **errp)
>>   {
>>       GuestPhysBlock *block;
>>       int64_t size;
>>       int ret;
>> +    Error *local_err = NULL;
>>
>>       while (1) {
>>           block = s->next_block;
>> @@ -633,34 +621,35 @@ static int dump_iterate(DumpState *s, Error **errp)
>>                   size -= block->target_end - (s->begin + s->length);
>>               }
>>           }
>> -        ret = write_memory(s, block, s->start, size, errp);
>> -        if (ret == -1) {
>> -            return ret;
>> +        write_memory(s, block, s->start, size, &local_err);
>> +        if (local_err) {
>> +            error_propagate(errp, local_err);
>> +            return;
>>           }
>>
>>           ret = get_next_block(s, block);
>>           if (ret == 1) {
>>               dump_completed(s);
>> -            return 0;
>>           }
>>       }
>>   }
>>
>> -static int create_vmcore(DumpState *s, Error **errp)
>> +static void create_vmcore(DumpState *s, Error **errp)
>>   {
>> -    int ret;
>> +    Error *local_err = NULL;
>>
>> -    ret = dump_begin(s, errp);
>> -    if (ret < 0) {
>> -        return -1;
>> +    dump_begin(s, &local_err);
>> +    if (local_err) {
>> +        error_propagate(errp, local_err);
>> +        return;
>>       }
>>
>> -    ret = dump_iterate(s, errp);
>> -    if (ret < 0) {
>> -        return -1;
>> +    dump_iterate(s, &local_err);
>> +    if (local_err) {
>> +        error_propagate(errp, local_err);
>> +        return;
>>       }
>>
>
> Please drop this blank line, like you do elsewhere.
>

OK!

>> -    return 0;
>>   }
>>
>
> You need local_err when you want to examine the error.  You do after
> dump_begin(), because you want to return early on error.  You don't
> after dump_iterate().  There, you could simply call
>
>      dump_iterate(s, errp);
>
> and be done with it.  Your choice.
>

You are right, it is unnecessary. Will remove this check. Thanks;)

>>   static int write_start_flat_header(int fd)
>> @@ -741,9 +730,8 @@ static int buf_write_note(const void *buf, size_t size, void *opaque)
>>   }
>>
>>   /* write common header, sub header and elf note to vmcore */
>> -static int create_header32(DumpState *s, Error **errp)
>> +static void create_header32(DumpState *s, Error **errp)
>>   {
>> -    int ret = 0;
>>       DiskDumpHeader32 *dh = NULL;
>>       KdumpSubHeader32 *kh = NULL;
>>       size_t size;
>> @@ -752,6 +740,7 @@ static int create_header32(DumpState *s, Error **errp)
>>       uint32_t bitmap_blocks;
>>       uint32_t status = 0;
>>       uint64_t offset_note;
>> +    Error *local_err = NULL;
>>
>>       /* write common header, the version of kdump-compressed format is 6th */
>>       size = sizeof(DiskDumpHeader32);
>> @@ -788,7 +777,6 @@ static int create_header32(DumpState *s, Error **errp)
>>
>>       if (write_buffer(s->fd, 0, dh, size) < 0) {
>>           dump_error(s, "dump: failed to write disk dump header", errp);
>> -        ret = -1;
>>           goto out;
>>       }
>>
>> @@ -808,7 +796,6 @@ static int create_header32(DumpState *s, Error **errp)
>>       if (write_buffer(s->fd, DISKDUMP_HEADER_BLOCKS *
>>                        block_size, kh, size) < 0) {
>>           dump_error(s, "dump: failed to write kdump sub header", errp);
>> -        ret = -1;
>>           goto out;
>>       }
>>
>> @@ -817,15 +804,14 @@ static int create_header32(DumpState *s, Error **errp)
>>       s->note_buf_offset = 0;
>>
>>       /* use s->note_buf to store notes temporarily */
>> -    if (write_elf32_notes(buf_write_note, s, errp) < 0) {
>> -        ret = -1;
>> +    write_elf32_notes(buf_write_note, s, &local_err);
>> +    if (local_err) {
>> +        error_propagate(errp, local_err);
>>           goto out;
>>       }
>> -
>>       if (write_buffer(s->fd, offset_note, s->note_buf,
>>                        s->note_size) < 0) {
>>           dump_error(s, "dump: failed to write notes", errp);
>> -        ret = -1;
>>           goto out;
>>       }
>>
>> @@ -841,14 +827,11 @@ out:
>>       g_free(dh);
>>       g_free(kh);
>>       g_free(s->note_buf);
>> -
>> -    return ret;
>>   }
>>
>>   /* write common header, sub header and elf note to vmcore */
>> -static int create_header64(DumpState *s, Error **errp)
>> +static void create_header64(DumpState *s, Error **errp)
>>   {
>> -    int ret = 0;
>>       DiskDumpHeader64 *dh = NULL;
>>       KdumpSubHeader64 *kh = NULL;
>>       size_t size;
>> @@ -857,6 +840,7 @@ static int create_header64(DumpState *s, Error **errp)
>>       uint32_t bitmap_blocks;
>>       uint32_t status = 0;
>>       uint64_t offset_note;
>> +    Error *local_err = NULL;
>>
>>       /* write common header, the version of kdump-compressed format is 6th */
>>       size = sizeof(DiskDumpHeader64);
>> @@ -893,7 +877,6 @@ static int create_header64(DumpState *s, Error **errp)
>>
>>       if (write_buffer(s->fd, 0, dh, size) < 0) {
>>           dump_error(s, "dump: failed to write disk dump header", errp);
>> -        ret = -1;
>>           goto out;
>>       }
>>
>> @@ -913,7 +896,6 @@ static int create_header64(DumpState *s, Error **errp)
>>       if (write_buffer(s->fd, DISKDUMP_HEADER_BLOCKS *
>>                        block_size, kh, size) < 0) {
>>           dump_error(s, "dump: failed to write kdump sub header", errp);
>> -        ret = -1;
>>           goto out;
>>       }
>>
>> @@ -922,15 +904,15 @@ static int create_header64(DumpState *s, Error **errp)
>>       s->note_buf_offset = 0;
>>
>>       /* use s->note_buf to store notes temporarily */
>> -    if (write_elf64_notes(buf_write_note, s, errp) < 0) {
>> -        ret = -1;
>> +    write_elf64_notes(buf_write_note, s, &local_err);
>> +    if (local_err) {
>> +        error_propagate(errp, local_err);
>>           goto out;
>>       }
>>
>>       if (write_buffer(s->fd, offset_note, s->note_buf,
>>                        s->note_size) < 0) {
>>           dump_error(s, "dump: failed to write notes", errp);
>> -        ret = -1;
>>           goto out;
>>       }
>>
>> @@ -946,16 +928,19 @@ out:
>>       g_free(dh);
>>       g_free(kh);
>>       g_free(s->note_buf);
>> -
>> -    return ret;
>>   }
>>
>> -static int write_dump_header(DumpState *s, Error **errp)
>> +static void write_dump_header(DumpState *s, Error **errp)
>>   {
>> +     Error *local_err = NULL;
>> +
>>       if (s->dump_info.d_class == ELFCLASS32) {
>> -        return create_header32(s, errp);
>> +        create_header32(s, &local_err);
>>       } else {
>> -        return create_header64(s, errp);
>> +        create_header64(s, &local_err);
>> +    }
>> +    if (local_err) {
>> +        error_propagate(errp, local_err);
>>       }
>>   }
>>
>> @@ -1069,7 +1054,7 @@ static bool get_next_page(GuestPhysBlock **blockptr, uint64_t *pfnptr,
>>       return true;
>>   }
>>
>> -static int write_dump_bitmap(DumpState *s, Error **errp)
>> +static void write_dump_bitmap(DumpState *s, Error **errp)
>>   {
>>       int ret = 0;
>>       uint64_t last_pfn, pfn;
>> @@ -1091,7 +1076,6 @@ static int write_dump_bitmap(DumpState *s, Error **errp)
>>           ret = set_dump_bitmap(last_pfn, pfn, true, dump_bitmap_buf, s);
>>           if (ret < 0) {
>>               dump_error(s, "dump: failed to set dump_bitmap", errp);
>> -            ret = -1;
>>               goto out;
>>           }
>>
>> @@ -1109,7 +1093,6 @@ static int write_dump_bitmap(DumpState *s, Error **errp)
>>                                 dump_bitmap_buf, s);
>>           if (ret < 0) {
>>               dump_error(s, "dump: failed to sync dump_bitmap", errp);
>> -            ret = -1;
>>               goto out;
>>           }
>>       }
>> @@ -1119,8 +1102,6 @@ static int write_dump_bitmap(DumpState *s, Error **errp)
>>
>>   out:
>>       g_free(dump_bitmap_buf);
>> -
>> -    return ret;
>>   }
>>
>>   static void prepare_data_cache(DataCache *data_cache, DumpState *s,
>> @@ -1200,7 +1181,7 @@ static inline bool is_zero_page(const uint8_t *buf, size_t page_size)
>>       return buffer_is_zero(buf, page_size);
>>   }
>>
>> -static int write_dump_pages(DumpState *s, Error **errp)
>> +static void write_dump_pages(DumpState *s, Error **errp)
>>   {
>>       int ret = 0;
>>       DataCache page_desc, page_data;
>> @@ -1365,13 +1346,12 @@ out:
>>   #endif
>>
>>       g_free(buf_out);
>> -
>> -    return ret;
>>   }
>>
>> -static int create_kdump_vmcore(DumpState *s, Error **errp)
>> +static void create_kdump_vmcore(DumpState *s, Error **errp)
>>   {
>>       int ret;
>> +    Error *local_err = NULL;
>>
>>       /*
>>        * the kdump-compressed format is:
>> @@ -1398,33 +1378,34 @@ static int create_kdump_vmcore(DumpState *s, Error **errp)
>>       ret = write_start_flat_header(s->fd);
>>       if (ret < 0) {
>>           dump_error(s, "dump: failed to write start flat header", errp);
>> -        return -1;
>> +        return;
>>       }
>>
>> -    ret = write_dump_header(s, errp);
>> -    if (ret < 0) {
>> -        return -1;
>> +    write_dump_header(s, &local_err);
>> +    if (local_err) {
>> +        error_propagate(errp, local_err);
>> +        return;
>>       }
>>
>> -    ret = write_dump_bitmap(s, errp);
>> -    if (ret < 0) {
>> -        return -1;
>> +    write_dump_bitmap(s, &local_err);
>> +    if (local_err) {
>> +        error_propagate(errp, local_err);
>> +        return;
>>       }
>>
>> -    ret = write_dump_pages(s, errp);
>> -    if (ret < 0) {
>> -        return -1;
>> +    write_dump_pages(s, &local_err);
>> +    if (local_err) {
>> +        error_propagate(errp, local_err);
>> +        return;
>>       }
>>
>>       ret = write_end_flat_header(s->fd);
>>       if (ret < 0) {
>>           dump_error(s, "dump: failed to write end flat header", errp);
>> -        return -1;
>> +        return;
>>       }
>>
>>       dump_completed(s);
>> -
>> -    return 0;
>>   }
>>
>>   static ram_addr_t get_start_block(DumpState *s)
>> @@ -1463,9 +1444,9 @@ static void get_max_mapnr(DumpState *s)
>>       s->max_mapnr = paddr_to_pfn(last_block->target_end);
>>   }
>>
>> -static int dump_init(DumpState *s, int fd, bool has_format,
>> -                     DumpGuestMemoryFormat format, bool paging, bool has_filter,
>> -                     int64_t begin, int64_t length, Error **errp)
>> +static void dump_init(DumpState *s, int fd, bool has_format,
>> +                      DumpGuestMemoryFormat format, bool paging, bool has_filter,
>> +                      int64_t begin, int64_t length, Error **errp)
>>   {
>>       CPUState *cpu;
>>       int nr_cpus;
>> @@ -1570,7 +1551,7 @@ static int dump_init(DumpState *s, int fd, bool has_format,
>>               s->flag_compress = 0;
>>           }
>>
>> -        return 0;
>> +        return;
>>       }
>>
>>       if (s->has_filter) {
>> @@ -1619,11 +1600,10 @@ static int dump_init(DumpState *s, int fd, bool has_format,
>>           }
>>       }
>>
>> -    return 0;
>> +    return;
>>
>>   cleanup:
>>       dump_cleanup(s);
>> -    return -1;
>>   }
>>
>>   void qmp_dump_guest_memory(bool paging, const char *file, bool has_begin,
>> @@ -1634,7 +1614,7 @@ void qmp_dump_guest_memory(bool paging, const char *file, bool has_begin,
>>       const char *p;
>>       int fd = -1;
>>       DumpState *s;
>> -    int ret;
>> +    Error *local_err = NULL;
>>
>>       /*
>>        * kdump-compressed format need the whole memory dumped, so paging or
>> @@ -1694,19 +1674,22 @@ void qmp_dump_guest_memory(bool paging, const char *file, bool has_begin,
>>
>>       s = g_malloc0(sizeof(DumpState));
>>
>> -    ret = dump_init(s, fd, has_format, format, paging, has_begin,
>> -                    begin, length, errp);
>> -    if (ret < 0) {
>> +    dump_init(s, fd, has_format, format, paging, has_begin,
>> +              begin, length, &local_err);
>> +    if (local_err) {
>>           g_free(s);
>> +        error_propagate(errp, local_err);
>>           return;
>>       }
>>
>>       if (has_format && format != DUMP_GUEST_MEMORY_FORMAT_ELF) {
>> -        create_kdump_vmcore(s, errp);
>> +        create_kdump_vmcore(s, &local_err);
>>       } else {
>> -        create_vmcore(s, errp);
>> +        create_vmcore(s, &local_err);
>> +    }
>> +    if (local_err) {
>> +        error_propagate(errp, local_err);
>>       }
>> -
>>       g_free(s);
>>   }
>
> Another case where local_err isn't needed.  You could simplify to just
>
>      if (has_format && format != DUMP_GUEST_MEMORY_FORMAT_ELF) {
>          create_kdump_vmcore(s, errp);
>      } else {
>          create_vmcore(s, errp);
>      }
>      g_free(s);
>
>

OK, Will fix it. Thanks.

> This patch illustrates why I dislike void functions with an Error **
> parameter: lots of busy-work with error_propagate().  But others feel
> it's what we should do.  *shrug*
>

;)

> Patch looks correct to me on a glance.  I'm leaving real review to the
> folks who think it's what we should do.
>
> .
>

Re: [Qemu-devel] [PATCH v6 0/2] dump: let dump_error return error reason to caller

[zhanghailiang]

Hi,

  Ping...

Thanks,
zhanghailiang

On 2014/9/19 14:43, zhanghailiang wrote:
> Hi,
>
> In original code, Function dump_error ignores its second parameter which contains
> error reason, it is better to return the error message to the caller.
>
> Here we use error_setg to return the error info to caller.
> And at the same time, we turn functions like write_elf64_note() to void,
> Because functions shouldn't return an error code _and_ an Error object.
> After this modification the code will be more clean.
>
> v5 -> v6
> - Don't check *errp directly, if errp is NULL, there will be an error,
>    Instead, check a local variable *local_err (Markus Armbruster)
> v4 -> v5:
> - Turn functions like write_elf64_note() to void (Luiz Capitulino)
> v3 -> v4:
> - Adjust the errp argument to the end
> - Remove trailing '.' in error messages
> v2 -> v3:
> - Drop the '\n' in the message when call dump_error(Eric Blake)
> v1 -> v2:
> - Return the error reason to the caller (Luiz Capitulino)
>
> zhanghailiang (2):
>    dump: let dump_error return error info to caller
>    dump: Don't return error code when return an Error object
>
>   dump.c | 382 +++++++++++++++++++++++++++++++----------------------------------
>   1 file changed, 182 insertions(+), 200 deletions(-)
>

Re: [Qemu-devel] [PATCH v6 0/2] dump: let dump_error return error reason to caller

[zhanghailiang]

Hi,

Ping^2...

Can anyone help reviewing this patch? Luiz? Eric? Markus? Thanks;)

Best regards,
zhanghailiang

On 2014/9/24 8:39, zhanghailiang wrote:
> Hi,
>
>   Ping...
>
> Thanks,
> zhanghailiang
>
> On 2014/9/19 14:43, zhanghailiang wrote:
>> Hi,
>>
>> In original code, Function dump_error ignores its second parameter which contains
>> error reason, it is better to return the error message to the caller.
>>
>> Here we use error_setg to return the error info to caller.
>> And at the same time, we turn functions like write_elf64_note() to void,
>> Because functions shouldn't return an error code _and_ an Error object.
>> After this modification the code will be more clean.
>>
>> v5 -> v6
>> - Don't check *errp directly, if errp is NULL, there will be an error,
>>    Instead, check a local variable *local_err (Markus Armbruster)
>> v4 -> v5:
>> - Turn functions like write_elf64_note() to void (Luiz Capitulino)
>> v3 -> v4:
>> - Adjust the errp argument to the end
>> - Remove trailing '.' in error messages
>> v2 -> v3:
>> - Drop the '\n' in the message when call dump_error(Eric Blake)
>> v1 -> v2:
>> - Return the error reason to the caller (Luiz Capitulino)
>>
>> zhanghailiang (2):
>>    dump: let dump_error return error info to caller
>>    dump: Don't return error code when return an Error object
>>
>>   dump.c | 382 +++++++++++++++++++++++++++++++----------------------------------
>>   1 file changed, 182 insertions(+), 200 deletions(-)
>>
>
>
>
>
>