* [PATCH 1/2] libtraceevent utest: Handle short reads when reading BTF
2026-06-01 10:37 [PATCH 0/2] libtraceevent: Fix BTF utest host dependencies Cao Ruichuang
@ 2026-06-01 10:37 ` Cao Ruichuang
2026-06-01 14:11 ` Steven Rostedt
2026-06-01 10:37 ` [PATCH 2/2] libtraceevent utest: Avoid host-specific getname_flags output Cao Ruichuang
1 sibling, 1 reply; 4+ messages in thread
From: Cao Ruichuang @ 2026-06-01 10:37 UTC (permalink / raw)
To: Steven Rostedt
Cc: linux-trace-devel, Tzvetomir Stoyanov, Emil Thorsoe,
Cao Ruichuang
test_btf_read() falls back to malloc() and read() when mmap() of
/sys/kernel/btf/vmlinux fails. The fallback currently assumes that one
read(fd, buf, st.st_size) call returns the whole file.
That is not guaranteed. On a Rocky Linux 9.7 system with a readable
/sys/kernel/btf/vmlinux, mmap() fails with ENODEV and a single read()
returns only 4096 bytes from a 5150407-byte file. Reading in a loop
returns the complete file.
Read the BTF file in a loop so the fallback path handles short reads
correctly and avoids passing partial BTF data to tep_load_btf().
Fixes: 5b44859765fc ("libtraceevent utest: Read btf file in utest if mmap fails")
Assisted-by: Codex:gpt-5.5
Signed-off-by: Cao Ruichuang <create0818@163.com>
---
utest/traceevent-utest.c | 33 ++++++++++++++++++++++++++++++++-
1 file changed, 32 insertions(+), 1 deletion(-)
diff --git a/utest/traceevent-utest.c b/utest/traceevent-utest.c
index 1c3a4c2..b93d686 100644
--- a/utest/traceevent-utest.c
+++ b/utest/traceevent-utest.c
@@ -9,6 +9,7 @@
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
+#include <errno.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
@@ -506,6 +507,28 @@ static void test_parse_dma_addr(void)
data, sizeof(data), "dma=0x1234abcd");
}
+static int read_full(int fd, void *buf, size_t size)
+{
+ char *data = buf;
+ size_t total = 0;
+
+ while (total < size) {
+ ssize_t ret;
+
+ ret = read(fd, data + total, size - total);
+ if (ret < 0) {
+ if (errno == EINTR)
+ continue;
+ return -1;
+ }
+ if (!ret)
+ return -1;
+ total += ret;
+ }
+
+ return 0;
+}
+
static void test_btf_read(void)
{
uint64_t args[] = {0x7ffe7d33f3d0, 0, 0, 0, 0, 0};
@@ -525,6 +548,8 @@ static void test_btf_read(void)
buf = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
if (buf == MAP_FAILED) {
+ int ret;
+
malloced = true;
buf = malloc(st.st_size);
if (buf == NULL) {
@@ -532,7 +557,13 @@ static void test_btf_read(void)
close(fd);
return;
}
- CU_TEST(read(fd, buf, st.st_size) == st.st_size);
+ ret = read_full(fd, buf, st.st_size);
+ CU_TEST(ret == 0);
+ if (ret < 0) {
+ free(buf);
+ close(fd);
+ return;
+ }
}
CU_TEST(tep_load_btf(test_tep, buf, st.st_size) == 0);
--
2.39.5 (Apple Git-154)
^ permalink raw reply related [flat|nested] 4+ messages in thread* [PATCH 2/2] libtraceevent utest: Avoid host-specific getname_flags output
2026-06-01 10:37 [PATCH 0/2] libtraceevent: Fix BTF utest host dependencies Cao Ruichuang
2026-06-01 10:37 ` [PATCH 1/2] libtraceevent utest: Handle short reads when reading BTF Cao Ruichuang
@ 2026-06-01 10:37 ` Cao Ruichuang
1 sibling, 0 replies; 4+ messages in thread
From: Cao Ruichuang @ 2026-06-01 10:37 UTC (permalink / raw)
To: Steven Rostedt
Cc: linux-trace-devel, Tzvetomir Stoyanov, Emil Thorsoe,
Cao Ruichuang
test_btf_read() loads /sys/kernel/btf/vmlinux and expects
getname_flags() to print exactly two arguments:
getname_flags(filename=0x7ffe7d33f3d0, flags=0)
That prototype is not stable across kernels. On a Rocky Linux 9.7
system, the kernel BTF for getname_flags() has a third parameter named
empty, and tep_btf_print_args() correctly prints it.
Keep the exact output check for hosts that match the expected prototype.
For hosts that append extra getname_flags() BTF parameters after the
expected arguments, treat that host-specific suffix as an acceptable
variant only if the output still has the expected argument prefix and a
complete closing suffix.
Fixes: 0294b73f17e9 ("libtraceevent utest: Add simple test to test BTF parsing")
Assisted-by: Codex:gpt-5.5
Signed-off-by: Cao Ruichuang <create0818@163.com>
---
utest/traceevent-utest.c | 20 +++++++++++++++++++-
1 file changed, 19 insertions(+), 1 deletion(-)
diff --git a/utest/traceevent-utest.c b/utest/traceevent-utest.c
index b93d686..04f6726 100644
--- a/utest/traceevent-utest.c
+++ b/utest/traceevent-utest.c
@@ -16,6 +16,7 @@
#include <time.h>
#include <dirent.h>
#include <ftw.h>
+#include <string.h>
#include <sys/mman.h>
#include <stdint.h>
@@ -529,10 +530,21 @@ static int read_full(int fd, void *buf, size_t size)
return 0;
}
+static bool output_has_extra_args(const char *output, const char *prefix)
+{
+ size_t len = strlen(output);
+ size_t plen = strlen(prefix);
+
+ return len > plen + 3 && strncmp(output, prefix, plen) == 0 &&
+ output[plen] == ',' && strcmp(output + len - 2, ")\n") == 0;
+}
+
static void test_btf_read(void)
{
uint64_t args[] = {0x7ffe7d33f3d0, 0, 0, 0, 0, 0};
const char *func = "getname_flags";
+ const char *expected = "getname_flags(filename=0x7ffe7d33f3d0, flags=0)\n";
+ const char *expected_prefix = "getname_flags(filename=0x7ffe7d33f3d0, flags=0";
struct trace_seq *s = test_seq;
struct stat st;
void *buf;
@@ -582,7 +594,13 @@ static void test_btf_read(void)
trace_seq_puts(s, ")\n");
trace_seq_terminate(s);
- CU_TEST(strcmp(s->buffer, "getname_flags(filename=0x7ffe7d33f3d0, flags=0)\n") == 0);
+ if (strcmp(s->buffer, expected) != 0 &&
+ output_has_extra_args(s->buffer, expected_prefix)) {
+ printf("[KERNEL BTF HAS EXTRA getname_flags ARGS] ...");
+ return;
+ }
+
+ CU_TEST(strcmp(s->buffer, expected) == 0);
}
static int test_suite_destroy(void)
--
2.39.5 (Apple Git-154)
^ permalink raw reply related [flat|nested] 4+ messages in thread