Messages in this thread | | | Date | Wed, 26 Jul 2023 21:46:13 -0700 | From | Jakub Kicinski <> | Subject | Re: [PATCH] mISDN: hfcpci: Fix potential deadlock on &hc->lock |
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On Tue, 25 Jul 2023 17:37:28 +0000 Chengfeng Ye wrote: > As &hc->lock is acquired by both timer _hfcpci_softirq() and hardirq > hfcpci_int(), the timer should disable irq before lock acquisition > otherwise deadlock could happen if the timmer is preemtped by the hadr irq. > > Possible deadlock scenario: > hfcpci_softirq() (timer) > -> _hfcpci_softirq() > -> spin_lock(&hc->lock); > <irq interruption> > -> hfcpci_int() > -> spin_lock(&hc->lock); (deadlock here) > > This flaw was found by an experimental static analysis tool I am developing > for irq-related deadlock. > > The tentative patch fixes the potential deadlock by spin_lock_irq() > in timer. > > But the patch could be not enough since between the lock critical section > inside the timer, tx_birq() is called in which a lot of stuff is executed > such as dev_kfree_skb(). I am not sure what's the best way to solve this > potential deadlock problem.
Yeah, the dev_kfree_skb() should be dev_kfree_skb_any() or _irq()
> Signed-off-by: Chengfeng Ye <dg573847474@gmail.com>
LGTM, but please repost with a Fixes tag added. -- pw-bot: cr
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