There is a deadlock in irdma_cleanup_cm_core(), which is shown
below:
(Thread 1) | (Thread 2)
| irdma_schedule_cm_timer()
irdma_cleanup_cm_core() | add_timer()
spin_lock_irqsave() //(1) | (wait a time)
... | irdma_cm_timer_tick()
del_timer_sync() | spin_lock_irqsave() //(2)
(wait timer to stop) | ...
We hold cm_core->ht_lock in position (1) of thread 1 and
use del_timer_sync() to wait timer to stop, but timer handler
also need cm_core->ht_lock in position (2) of thread 2.
As a result, irdma_cleanup_cm_core() will block forever.
This patch extracts del_timer_sync() from the protection of
spin_lock_irqsave(), which could let timer handler to obtain
the needed lock.
Signed-off-by: Duoming Zhou <duoming@xxxxxxxxxx>
---
drivers/infiniband/hw/irdma/cm.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/infiniband/hw/irdma/cm.c b/drivers/infiniband/hw/irdma/cm.c
index dedb3b7edd8..019dd8bfe08 100644
--- a/drivers/infiniband/hw/irdma/cm.c
+++ b/drivers/infiniband/hw/irdma/cm.c
@@ -3252,8 +3252,11 @@ void irdma_cleanup_cm_core(struct irdma_cm_core *cm_core)
return;
spin_lock_irqsave(&cm_core->ht_lock, flags);
- if (timer_pending(&cm_core->tcp_timer))
+ if (timer_pending(&cm_core->tcp_timer)) {
+ spin_unlock_irqrestore(&cm_core->ht_lock, flags);
del_timer_sync(&cm_core->tcp_timer);
+ spin_lock_irqsave(&cm_core->ht_lock, flags);
+ }
spin_unlock_irqrestore(&cm_core->ht_lock, flags);
destroy_workqueue(cm_core->event_wq);
--
2.17.1
