The patch implements what Dima Monakhov suggested:
> AFAIU you have a re-entrance issue if several tasks want performs ioctls
> task1:ioctl->wait
> task2:ioctl->wait
>
> Just change wait sequence like this and you are safe:
> /* blocking case */
> if (unlikely(pbd->ppb_waiting))
> /* Other task is already waitng for event */
> err = -EBUSY;
> goto get_pending_unlock;
> }
> pbd->ppb_waiting = true;
> spin_unlock(&pbd->ppb_lock);
> mutex_unlock(&plo->ctl_mutex);
Signed-off-by: Maxim Patlasov <mpatla...@virtuozzo.com>
---
drivers/block/ploop/push_backup.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/drivers/block/ploop/push_backup.c
b/drivers/block/ploop/push_backup.c
index 4d671a5..10fd55a 100644
--- a/drivers/block/ploop/push_backup.c
+++ b/drivers/block/ploop/push_backup.c
@@ -466,6 +466,11 @@ int ploop_pb_get_pending(struct ploop_pushbackup_desc *pbd,
}
/* blocking case */
+ if (unlikely(pbd->ppb_waiting)) {
+ /* Other task is already waitng for event */
+ err = -EBUSY;
+ goto get_pending_unlock;
+ }
pbd->ppb_waiting = true;
spin_unlock(&pbd->ppb_lock);
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