Messages in this thread | | | Subject | Re: [BUG] sound: pci: trident: a possible data race | From | Jia-Ju Bai <> | Date | Thu, 4 Oct 2018 17:17:52 +0800 |
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On 2018/10/4 13:24, Takashi Iwai wrote: > On Thu, 04 Oct 2018 05:08:45 +0200, > Jia-Ju Bai wrote: >> Thanks for the reply :) >> >> >> On 2018/10/3 23:54, Takashi Iwai wrote: >>> On Wed, 03 Oct 2018 14:50:25 +0200, >>> Jia-Ju Bai wrote: >>>> CPU0: >>>> snd_trident_hw_free >>>> snd_trident_free_voice >>>> line 3870: spin_lock_irqsave() >>>> line 3881: voice->substream = NULL; [WRITE] >>>> CPU1: >>>> snd_trident_interrupt >>>> line 3798: snd_pcm_period_elapsed(voice->substream); [READ] >>>> >>>> As for voice->substream, the WRITE operation in CPU0 is performed >>>> with holding a spinlock, but the READ operation in CPU1 is performed >>>> without holding this spinlock, so there may exist a data race. >>> Thanks for the report. >>> >>> The actual crash must be very unlikely, almost 0%, though. >>> snd_trident_hw_free() is called always after the PCM stream gets >>> stopped via trigger callback, i.e. at the moment, there is no >>> corresponding interrupt is generated for that voice entry. >> How about the case that playback and capture are performed concurrently? >> Namely, snd_trident_hw_free() is called for playback, and the >> interrupt is generated for capture. > They are different substreams, hence it won't pick up the substream > object.
Actually, I performed a runtime testing, and found that snd_trident_hw_free() and snd_trident_interrupt() are executed concurrently. However, I did not check the substream object, so I guess this report was produced in the case that I mentioned. Anyway, my report should be false, sorry...
Best wishes, Jia-Ju Bai
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