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Wed, 17 Jun 2026 08:53:09 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id r8hzDHVgMmrFRQAAD6G6ig (envelope-from ); Wed, 17 Jun 2026 08:53:09 +0000 Date: Wed, 17 Jun 2026 10:53:08 +0200 Message-ID: <87tsr1pmyz.wl-tiwai@suse.de> From: Takashi Iwai To: Jaroslav Kysela Cc: Ai Chao , tiwai@suse.com, kees@kernel.org, linux-sound@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] ALSA: pcm: Show closed for DISCONNECTED state In-Reply-To: <0888c20f-0a0f-458f-9a73-f05d85ecddaa@perex.cz> References: <20260617071951.3357788-1-aichao@kylinos.cn> <0888c20f-0a0f-458f-9a73-f05d85ecddaa@perex.cz> User-Agent: Wanderlust/2.15.9 (Almost Unreal) Emacs/30.2 Mule/6.0 Precedence: bulk X-Mailing-List: linux-sound@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-Spam-Flag: NO X-Rspamd-Action: no action X-Spam-Level: X-Spamd-Result: default: False [-3.51 / 50.00]; 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DKIM_TRACE(0.00)[suse.de:+] X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Rspamd-Queue-Id: 6E2176B6D5 X-Spam-Score: -3.51 On Wed, 17 Jun 2026 10:36:44 +0200, Jaroslav Kysela wrote: > > On 6/17/26 09:19, Ai Chao wrote: > > Hello Takashi > > > >> Thanks, it's a bit clearer. But it still means that it's a cargo fix > >> only for that specific application. The program should receive an > >> error for any further syscalls, so that it can close gracefully by > >> itself. Or it doesn't work as expected? > > > > The recording software monitors /proc/asound/card0/pcm0c/sub0/status. > > When the USB device is suddenly disconnected, the recording software fails > > to capture audio data from the sound card, with both the hardware pointer > > and application pointer being 0. The software remains in a pending state, > > continuously displaying "Generating recording file". If the status file shows > > "closed" (DISCONNECTED), the audio service detects the status change, reinitializes > > the device, starts processing the recording file, and either resumes recording or > > notifies the user. > > The PCM API ioctls should return an error in this case (device > disconnection). Does software communicate with the driver through > ioctl ? It seems that only mmaped appl/hw pointers are used which is > not enough to detect the disconnection. Right, I suspect that it might be the case. Does the change like below help (or worsen) anything? Takashi -- 8< -- --- a/sound/core/pcm_native.c +++ b/sound/core/pcm_native.c @@ -3907,6 +3907,8 @@ static vm_fault_t snd_pcm_mmap_data_fault(struct vm_fault *vmf) if (substream == NULL) return VM_FAULT_SIGBUS; runtime = substream->runtime; + if (runtime->state == SNDRV_PCM_STATE_DISCONNECTED) + return VM_FAULT_SIGBUS; offset = vmf->pgoff << PAGE_SHIFT; dma_bytes = PAGE_ALIGN(runtime->dma_bytes); if (offset > dma_bytes - PAGE_SIZE)