Re: [PATCH]: Make migration handle errors a little better

[Chris Lalancette <clalance-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

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Uri Lublin wrote:
> Patch looks good.
> Why did you define MIG_STAT_DIRTY_TRACK_FAIL and not 
> MIG_STAT_KVM_SET_DIRTY_TRACKING_FAILED ?

Oops, I slightly misunderstood this bit in my last e-mail.  You were saying that
there is already a "MIG_STAT_KVM_SET_DIRTY_TRACKING_FAILED" error flag.  In the
new patch (attached), I've used this instead.

> Also we need to make sure, in case of a failure, that 'status' is  
> updated and *s->has_error is freed. How about calling migrate_finish ?

And I now call migrate_finish() instead of migrate_close() in the error path, as
you suggest.  Thanks again!

Signed-off-by: Chris Lalancette <clalance-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>

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diff --git a/qemu/migration.c b/qemu/migration.c
index 17ad77c..df0acf9 100644
--- a/qemu/migration.c
+++ b/qemu/migration.c
@@ -425,18 +425,26 @@ static int start_migration(MigrationState *s)
 #endif
 	
     r = MIG_STAT_WRITE_FAILED;
-    if (write_whole_buffer(s->fd, &running, sizeof(running)))
+    if (write_whole_buffer(s->fd, &running, sizeof(running))) {
+        perror("vm_running write failed");
         goto out;
-    if (write_whole_buffer(s->fd, &value, sizeof(value)))
+    }
+    if (write_whole_buffer(s->fd, &value, sizeof(value))) {
+        perror("phys_ram_size write failed");
         goto out;
+    }
 
 #ifdef USE_KVM
     if (kvm_allowed) {
         value = cpu_to_be32(n);
-        if (write_whole_buffer(s->fd, &value, sizeof(value)))
+        if (write_whole_buffer(s->fd, &value, sizeof(value))) {
+            perror("phys_ram_size_bitmap size write failed");
             goto out;
-        if (write_whole_buffer(s->fd, phys_ram_page_exist_bitmap, n))
+	}
+        if (write_whole_buffer(s->fd, phys_ram_page_exist_bitmap, n)) {
+            perror("phys_ram_page_exist_bitmap write failed");
             goto out;
+	}
     }
 #endif
     fcntl(s->fd, F_SETFL, O_NONBLOCK);
@@ -456,7 +464,8 @@ static int start_migration(MigrationState *s)
 
     if (cpu_physical_memory_set_dirty_tracking(1)) {
         *s->has_error = MIG_STAT_KVM_SET_DIRTY_TRACKING_FAILED;
-        return -1;
+        r = MIG_STAT_KVM_SET_DIRTY_TRACKING_FAILED;
+        goto out;
     }
 
     s->addr = 0;
@@ -470,6 +479,8 @@ static int start_migration(MigrationState *s)
     qemu_mod_timer(s->timer, qemu_get_clock(rt_clock));
     qemu_set_fd_handler2(s->fd, NULL, NULL, migrate_write, s);
 
+    r = 0;
+
  out:
 #ifdef USE_KVM
     if (phys_ram_page_exist_bitmap)
@@ -498,8 +509,9 @@ static MigrationState *migration_init_fd(int detach, int fd)
 
     current_migration = s;
     
-    if (start_migration(s) == -1) {
+    if (start_migration(s)) {
 	term_printf("Could not start migration\n");
+	migrate_finish(s);
 	return NULL;
     }
 

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