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>
---
 block/blkdebug.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/block/blkdebug.c b/block/blkdebug.c
index 388b5ed615..dffd869b32 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;
 }
 
-- 
2.30.2

17.05.2021 17:50, Emanuele Giuseppe Esposito wrote:
> 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>
> ---
>   block/blkdebug.c | 7 ++++++-
>   1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/block/blkdebug.c b/block/blkdebug.c
> index 388b5ed615..dffd869b32 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;
>   }
>   
> 

Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

two thoughts:

  - suspend_request() should probably be renamed
  - actions_count logic is a bit overcomplicated, actually we need only suspend_count.

-- 
Best regards,
Vladimir