diff mbox series

[v5,4/6] blkdebug: do not suspend in the middle of QLIST_FOREACH_SAFE

Message ID 20210614082931.24925-5-eesposit@redhat.com
State New
Headers show
Series blkdebug: fix racing condition when iterating on | expand

Commit Message

Emanuele Giuseppe Esposito June 14, 2021, 8:29 a.m. UTC 
That would be unsafe in case a rule other than the current one
is removed while the coroutine has yielded.
Keep FOREACH_SAFE because suspend_request deletes the current rule.

After this patch, *all* matching rules are deleted before suspending
the coroutine, rather than just one.
This doesn't affect the existing testcases.

Use actions_count to see how many yield to issue.

Co-developed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 block/blkdebug.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/block/blkdebug.c b/block/blkdebug.c
index 6bdeb2c7b3..dd82131d1e 100644
--- a/block/blkdebug.c
+++ b/block/blkdebug.c
@@ -789,7 +789,6 @@  static void suspend_request(BlockDriverState *bs, BlkdebugRule *rule)
     if (!qtest_enabled()) {
         printf("blkdebug: Suspended request '%s'\n", r->tag);
     }
-    qemu_coroutine_yield();
 }
 
 static void process_rule(BlockDriverState *bs, struct BlkdebugRule *rule,
@@ -834,6 +833,12 @@  static void blkdebug_debug_event(BlockDriverState *bs, BlkdebugEvent event)
     QLIST_FOREACH_SAFE(rule, &s->rules[event], next, next) {
         process_rule(bs, rule, actions_count);
     }
+
+    while (actions_count[ACTION_SUSPEND] > 0) {
+        qemu_coroutine_yield();
+        actions_count[ACTION_SUSPEND]--;
+    }
+
     s->state = s->new_state;
 }