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b=OkzSRvr1/VtuZTVfWIGg10Dqd6lqsvndcEZeK+OUwELUVbbw1t0SxHq5jG4b24gmIE1bgQ C3B7mCp6u9PbT5CA== Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id D395A13408; Mon, 12 Oct 2026 14:51:40 +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 nylAKvzzzGp8SwAAD6G6ig (envelope-from ); Mon, 12 Oct 2026 14:51:40 +0000 Date: Mon, 12 Oct 2026 16:51:40 +0200 Message-ID: <87h5irgef7.wl-tiwai@suse.de> From: Takashi Iwai To: Ali Ahmet =?ISO-8859-2?Q?Memi=BA?= Cc: Takashi Iwai , Takashi Iwai , Jaroslav Kysela , linux-sound@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] ALSA: control_led: Fix deadlock between sysfs writes and card disconnect In-Reply-To: <20261012141238.1823718-1-aliamemis@disroot.org> References: <20261011180627.1594051-1-aliamemis@disroot.org> <874ieridp1.wl-tiwai@suse.de> <20261012141238.1823718-1-aliamemis@disroot.org> 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; 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TO_MATCH_ENVRCPT_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; DKIM_TRACE(0.00)[suse.de:+] X-Spam-Level: X-Rspamd-Queue-Id: 808CF21E1B X-Rspamd-Server: rspamd2.dmz-prg2.suse.org On Mon, 12 Oct 2026 16:12:35 +0200, Ali Ahmet Memiš wrote: > > On Mon, 12 Oct 2026 09:24:26 +0200, Takashi Iwai wrote: > > Hm, it's not clear to me how this happens: I see no controls_rwsem > > down around snd_ctl_led_disconnect() call. Could you elaborate about > > it a bit more? > > It's taken in the call_snd_ctl_lops() macro in control.c: > > guard(rwsem_read)(&(_card)->controls_rwsem); > guard(rwsem_read)(&snd_ctl_layer_rwsem); > > so snd_ctl_dev_disconnect() calls ->ldisconnect() with controls_rwsem > held for read. snd_ctl_led_sysfs_remove() then waits in kernfs_drain() > for the attach write which is blocked on down_write(controls_rwsem) in > snd_ctl_led_set_id(). Thanks, now it's clearer. The patch is applied to for-next branch now. thanks, Takashi