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Mon, 31 Aug 2026 08:04:24 +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 79oiJog1lWqveQAAD6G6ig (envelope-from ); Mon, 31 Aug 2026 08:04:24 +0000 Date: Mon, 31 Aug 2026 10:04:24 +0200 Message-ID: <87h5kasol3.wl-tiwai@suse.de> From: Takashi Iwai To: Will Porter Cc: Takashi Iwai , Jaroslav Kysela , "Geoffrey D. Bennett" , Asahi Lina , Chris J Arges , Nick Kossifidis , Detlef Urban , Roy Vegard Ovesen , fenugrec , Frederic Popp , =?ISO-8859-1?Q?C=E1ssio?= Gabriel , Shipei Qu , linux-sound@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/6] ALSA: usb-audio: guard device-specific control transfers In-Reply-To: <20260827232143.149197-1-mrwillporter@gmail.com> References: <20260824230302.27965-1-mrwillporter@gmail.com> <20260827232143.149197-1-mrwillporter@gmail.com> 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-Level: X-Rspamd-Action: no action X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Rspamd-Queue-Id: 2569622340 X-Spamd-Result: default: False [-2.01 / 50.00]; BAYES_HAM(-3.00)[100.00%]; SUSPICIOUS_RECIPS(1.50)[]; 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)[]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; RCPT_COUNT_TWELVE(0.00)[15]; 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]; FREEMAIL_ENVRCPT(0.00)[gmail.com,mail.com,t-online.de]; FREEMAIL_CC(0.00)[suse.com,perex.cz,b4.vu,asahilina.net,canonical.com,gmail.com,paraair.de,mail.com,t-online.de,darknavy.com,vger.kernel.org]; RCVD_COUNT_TWO(0.00)[2]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; RECEIVED_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:106:10:150:64:167:received]; RCVD_VIA_SMTP_AUTH(0.00)[]; TAGGED_RCPT(0.00)[]; RCVD_TLS_ALL(0.00)[]; DKIM_TRACE(0.00)[suse.de:+]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:rdns,imap1.dmz-prg2.suse.org:helo,suse.de:dkim,suse.de:mid] X-Spam-Flag: NO X-Spam-Score: -2.01 On Fri, 28 Aug 2026 01:21:37 +0200, Will Porter wrote: > > Takashi confirmed that hardware access through usb_ctl_msg() should hold > snd_usb_lock, and suggested guarding scarlett2_usb() as the central point > for Scarlett2. This series adds that protection to the six device-specific > paths identified by the RFC audit. > > Each guard covers a complete synchronous USB transaction. The guards are > outside private data and USB mutexes when a resume callback could affect > lock ordering. > > FCP holds one reference across its complete initialization sequence so > runtime suspend cannot intervene between step zero, notification-URB setup, > and the two initialization commands. > > Scarlett2 uses a dedicated unguarded helper only for the suspend-time config > save. That call already runs inside the USB suspend callback. The guarded > path covers normal controls and hwdep operations. The series does not claim > to hold a PM reference across Scarlett2's asynchronous flash-erase interval. > > The affected devices were unavailable for runtime testing. I reproduced the > failure mechanism with an Audient iD14 MkI mixer path before the RFC. I then > built the complete sound/usb/ directory with the configuration from the > running x86-64 distribution kernel (7.2.0-ogc4.1.fc44.x86_64): > > make olddefconfig > make -j4 W=1 sound/usb/ > > All six changed objects compiled without warnings, and the build linked > sound/usb/snd-usb-audio.o. The series also passes scripts/checkpatch.pl > --strict with no errors, warnings, or checks. > > Link: https://lore.kernel.org/r/20260824230302.27965-1-mrwillporter@gmail.com > > Will Porter (6): > ALSA: usb-audio: Add PM guard to Studio 1810c controls > ALSA: usb-audio: Add PM guards to US-16x08 transfers > ALSA: usb-audio: Add PM guard to Scarlett meter reads > ALSA: usb-audio: Guard Scarlett2 protocol transfers > ALSA: usb-audio: Add PM guards to RME Digiface controls > ALSA: usb-audio: Guard FCP protocol transfers Applied all patches now. Thanks. Takashi