linux-kernel - Re: [PATCH] ALSA: usb-audio: Fix recursive locking on XRUN

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Message-ID: <20230318105928.GA87969@workstation>
Date:   Sat, 18 Mar 2023 19:59:28 +0900
From:   Takashi Sakamoto <o-takashi@...amocchi.jp>
To:     John Keeping <john@...anate.com>, Takashi Iwai <tiwai@...e.com>,
        "moderated list:SOUND" <alsa-devel@...a-project.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ALSA: usb-audio: Fix recursive locking on XRUN

On Sat, Mar 18, 2023 at 09:20:05AM +0900, Takashi Sakamoto wrote:
> 1. Failure at tasklet for URB completion
> 
> It is softIRQ context. The stream lock is not acquired. It doesn't
> matter to call current XRUN API.
> 
> 2. Failure at PCM operation called by ALSA PCM application
> 
> It is process context. The stream lock is acquired before calling driver
> code. When detecting any type of failure, driver code stores the state.
> Then .pointer callback should return SNDRV_PCM_IOCTL_HWSYNC refering to
> the state.

Oops. I did copy-and-paste mistake here... It should be
SNDRV_PCM_POS_XRUN instead of SNDRV_PCM_IOCTL_HWSYNC...


Regards

Takashi Sakamoto