Messages in this thread Patch in this message |  | | From | Duoming Zhou <> | Subject | [PATCH V5] drivers: infiniband: hw: Fix deadlock in irdma_cleanup_cm_core() | Date | Sun, 17 Apr 2022 21:14:14 +0800 |
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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 removes the check of timer_pending() in irdma_cleanup_cm_core(), because the del_timer_sync() function will just return directly if there isn't a pending timer. As a result, the lock is redundant, because there is no resource it could protect.
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn> --- Changes in V5: - Remove mod_timer() in irdma_schedule_cm_timer and irdma_cm_timer_tick.
drivers/infiniband/hw/irdma/cm.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-)
diff --git a/drivers/infiniband/hw/irdma/cm.c b/drivers/infiniband/hw/irdma/cm.c index dedb3b7edd8..4b6b1065f85 100644 --- a/drivers/infiniband/hw/irdma/cm.c +++ b/drivers/infiniband/hw/irdma/cm.c @@ -3251,10 +3251,7 @@ void irdma_cleanup_cm_core(struct irdma_cm_core *cm_core) if (!cm_core) return; - spin_lock_irqsave(&cm_core->ht_lock, flags); - if (timer_pending(&cm_core->tcp_timer)) - del_timer_sync(&cm_core->tcp_timer); - spin_unlock_irqrestore(&cm_core->ht_lock, flags); + del_timer_sync(&cm_core->tcp_timer); destroy_workqueue(cm_core->event_wq); cm_core->dev->ws_reset(&cm_core->iwdev->vsi); -- 2.17.1
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