* [BUG] net: netronome: nfp: possible deadlock in nfp_cpp_area_acquire() and nfp_cpp_area_release()
@ 2022-02-09 2:50 Jia-Ju Bai
2022-02-09 3:49 ` Jakub Kicinski
0 siblings, 1 reply; 2+ messages in thread
From: Jia-Ju Bai @ 2022-02-09 2:50 UTC (permalink / raw)
To: simon.horman, Jakub Kicinski, David Miller, shenyang39, libaokun1
Cc: oss-drivers, netdev, linux-kernel
Hello,
My static analysis tool reports a possible deadlock in the nfp driver in
Linux 5.16:
nfp_cpp_area_acquire()
mutex_lock(&area->mutex); --> Line 455 (Lock A)
__nfp_cpp_area_acquire()
wait_event_interruptible(area->cpp->waitq, ...) --> Line 427 (Wait X)
nfp_cpp_area_release()
mutex_lock(&area->mutex); --> Line 502 (Lock A)
wake_up_interruptible_all(&area->cpp->waitq); --> Line 508 (Wake X)
When nfp_cpp_area_acquire() is executed, "Wait X" is performed by
holding "Lock A". If nfp_cpp_area_release() is executed at this time,
"Wake X" cannot be performed to wake up "Wait X" in
nfp_cpp_area_acquire(), because "Lock A" has been already hold by
nfp_cpp_area_acquire(), causing a possible deadlock.
I am not quite sure whether this possible problem is real and how to fix
it if it is real.
Any feedback would be appreciated, thanks :)
Best wishes,
Jia-Ju Bai
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [BUG] net: netronome: nfp: possible deadlock in nfp_cpp_area_acquire() and nfp_cpp_area_release()
2022-02-09 2:50 [BUG] net: netronome: nfp: possible deadlock in nfp_cpp_area_acquire() and nfp_cpp_area_release() Jia-Ju Bai
@ 2022-02-09 3:49 ` Jakub Kicinski
0 siblings, 0 replies; 2+ messages in thread
From: Jakub Kicinski @ 2022-02-09 3:49 UTC (permalink / raw)
To: Jia-Ju Bai
Cc: simon.horman, David Miller, shenyang39, libaokun1, oss-drivers,
netdev, linux-kernel
On Wed, 9 Feb 2022 10:50:44 +0800 Jia-Ju Bai wrote:
> Hello,
>
> My static analysis tool reports a possible deadlock in the nfp driver in
> Linux 5.16:
>
> nfp_cpp_area_acquire()
> mutex_lock(&area->mutex); --> Line 455 (Lock A)
> __nfp_cpp_area_acquire()
> wait_event_interruptible(area->cpp->waitq, ...) --> Line 427 (Wait X)
>
> nfp_cpp_area_release()
> mutex_lock(&area->mutex); --> Line 502 (Lock A)
> wake_up_interruptible_all(&area->cpp->waitq); --> Line 508 (Wake X)
>
> When nfp_cpp_area_acquire() is executed, "Wait X" is performed by
> holding "Lock A". If nfp_cpp_area_release() is executed at this time,
> "Wake X" cannot be performed to wake up "Wait X" in
> nfp_cpp_area_acquire(), because "Lock A" has been already hold by
> nfp_cpp_area_acquire(), causing a possible deadlock.
>
> I am not quite sure whether this possible problem is real and how to fix
> it if it is real.
It's not.
> Any feedback would be appreciated, thanks :)
>
>
> Best wishes,
> Jia-Ju Bai
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2022-02-09 4:11 UTC | newest]
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2022-02-09 2:50 [BUG] net: netronome: nfp: possible deadlock in nfp_cpp_area_acquire() and nfp_cpp_area_release() Jia-Ju Bai
2022-02-09 3:49 ` Jakub Kicinski
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