Messages in this thread | | | From | Chengfeng Ye <> | Date | Fri, 30 Jun 2023 02:33:38 +0800 | Subject | Re: [PATCH v2] misc: bcm_vk: Fix potential deadlock on &vk->ctx_lock |
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> The timer function does not seem to be performance critical at all, > it might be nicer to just move it into process context using > a delayed workqueue instead of a timer.
Thanks for the suggestion, new patch is sent with a delayed workqueue.
Best Regards, Chengfeng
Arnd Bergmann <arnd@arndb.de> 于2023年6月28日周三 19:56写道: > > On Wed, Jun 28, 2023, at 13:29, Chengfeng Ye wrote: > > As &vk->ctx_lock is acquired by timer bcm_vk_hb_poll() under softirq > > context, other process context code should disable irq or bottom-half > > before acquire the same lock, otherwise deadlock could happen if the > > timer preempt the execution while the lock is held in process context > > on the same CPU. > > > > Possible deadlock scenario > > bcm_vk_open() > > -> bcm_vk_get_ctx() > > -> spin_lock(&vk->ctx_lock) > > <timer iterrupt> > > -> bcm_vk_hb_poll() > > -> bcm_vk_blk_drv_access() > > -> spin_lock_irqsave(&vk->ctx_lock, flags) (deadlock here) > > > > This flaw was found using an experimental static analysis tool we are > > developing for irq-related deadlock, which reported the following > > warning when analyzing the linux kernel 6.4-rc7 release. > > The timer function does not seem to be performance critical at all, > it might be nicer to just move it into process context using > a delayed workqueue instead of a timer. > > Arnd
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