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Mon, 26 Oct 2026 08:39:21 +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 9O9kHbkR32pdQgAAD6G6ig (envelope-from ); Mon, 26 Oct 2026 08:39:21 +0000 Date: Mon, 26 Oct 2026 09:39:21 +0100 Message-ID: <87o6cg6ekm.wl-tiwai@suse.de> From: Takashi Iwai To: Cen Zhang Cc: perex@perex.cz, tiwai@suse.com, linux-sound@vger.kernel.org, linux-kernel@vger.kernel.org, tiwai@suse.de, baijiaju1990@gmail.com, jjzuming@gmail.com Subject: Re: [PATCH v2 0/3] ALSA: pcm: Retain components across codec teardown In-Reply-To: References: User-Agent: Wanderlust/2.15.9 (Almost Unreal) Emacs/30.2 Mule/6.0 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-Spamd-Result: default: False [-12.51 / 50.00]; SUSE_INTERNAL_BYPASS(-9.00)[]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; MID_CONTAINS_FROM(1.00)[]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; RBL_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:104:10:150:64:97:from]; FREEMAIL_TO(0.00)[gmail.com]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; RCVD_TLS_ALL(0.00)[]; TO_DN_SOME(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; FREEMAIL_CC(0.00)[perex.cz,suse.com,vger.kernel.org,suse.de,gmail.com]; RCPT_COUNT_SEVEN(0.00)[8]; RCVD_VIA_SMTP_AUTH(0.00)[]; RECEIVED_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:106:10:150:64:167:received]; DKIM_TRACE(0.00)[suse.de:+]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:dkim,imap1.dmz-prg2.suse.org:rdns,imap1.dmz-prg2.suse.org:helo] X-Rspamd-Server: rspamd1.dmz-prg2.suse.org X-Rspamd-Action: no action X-Spam-Flag: NO X-Spam-Score: -12.51 X-Spam-Level: X-Rspamd-Queue-Id: 62AE81F7B9 On Sat, 24 Oct 2026 13:41:13 +0200, Cen Zhang wrote: > > A pending PCM opener can retain the card without retaining a PCM removed > by codec-only unbind. A late codec probe can also publish PCM devices > before a subsequent registration failure starts cleanup. > > Retain native and OSS PCM lookups through file release, close admission > at component disconnect, and drain codec users before probe-error cleanup. > Keep the existing proc rundown outside open_mutex at disconnect, and wait > for PCM references in final cleanup after the lookup gate is closed. > > --- > Cen Zhang (3): > ALSA: pcm: Retain components across native minor lookups > ALSA: pcm: oss: Retain the PCM from minor lookup through release > ALSA: hda: Drain PCM users before cleaning up a failed codec probe I guess fixing in lower layer would become a whack-a-mole game. My current thought is to rather plug on the upper layer, that is: - Serialize concurrent probe and remove calls for the same HD-audio bus - At remove, synchronize the all opened fds on the card; you can check list_empty(&card->files_list) and notify from snd_card_file_remove() call. The proc files are removed and synced at disconnection, so the above should cover most of corner cases, I suppose. thanks, Takashi