From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794047844; b=or7LcM98E9M94SZIZucjPmyU9FgnGiADleXzq++Ddxla2+21ePvm5mLDCP072xY5KiBY AXYYXbLG3c6/K4MuJPfraJZxDOpx29JMyXLeKJ9Phn1cm6bihJmbU39vf0G5cvbMaBnyc E7UfgnblRLmQHFl6KtZvzPYIiApzTH6/5Slf5vicYl2r0yNEoQTvdxQeB11zSzht7M9L6 Lh2rvoI2bWPFNHfdupXGlcgjcAt5FoBp6gTeZcK+Ni4NkgtUZUZZD4j4p9qvadvVMgEzP 8if5QJdFbTgBpyQi7V+cuwC6gzQqcTGotxryE6eGDZ689qzURpb7Z2IOi3a94pH4dzg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794047844; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=c9Is7DsVACIjLVFhNehNgejDjseV2rZPGl2uoiao+fc=; b=mV92Fu6onsl2lwpkyuK+hP7LWflTHGBqHvmpyY/OASwHYY1R4xtsF734+UMn+hygY6fN NLDTN5XplXzhFqOwcw2hpYJ+L872QIHS5o6PmDNywQ/xp0i44GoOUYJTmPfcrVshEqaQv FMpbCELE2hLqqa6Ektn5kgtcxCXr4iGxVZ97gJomE4ZrpuSNkpt1h+Z5/eDkyTtU7tsSQ x1xqWMAqJrIHsK801NB2obn1lgDV1EkMtW+QfrK8BYWAxPe1cKsZlY+0R0v/f7RQe1ZHp ijkLe8mYnLDbMBnsiB/dC1OgSFxJvbo7veo/tjjpSKkTMemqFMd7F8pTwt/Rh5Au9rg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=MoFKIemS; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A87ED606A326 for ; Sat, 7 Nov 2026 10:37:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=MoFKIemS Received: by smtp.kernel.org (Postfix) with ESMTPSA id 24F9F1F0089F; Sat, 7 Nov 2026 10:37:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794047843; bh=c9Is7DsVACIjLVFhNehNgejDjseV2rZPGl2uoiao+fc=; h=From:To:Cc:Subject:Date; b=MoFKIemSR73SReCF2xlgaJqjMAo808lI9fIb+NDazdICut0oq8NVMe2trEex7tILH AYrr2qlcgWPfC4KXs5HhZ5YOwVNObBpUHmT5Qbx+7upUtHyFisS279ajbjmrT/Y8r6 LwZtMITiH8uwY8bbgkbqWjOkCcFqiKDQbJD0esGZ6awjDFlkG6xDh/1kwF09JIZ3MY pqPiwCHmR7RIXtvYkQ19AvD4JZpHJNWGTZPlct/Bwb1NRh22yWhcyw6ESJIrW5DGWF KuzxnrlDAWqhkhVVBj92gd9K7Xo6uWO7BNVflMW7nk9YRadwdf0U5CynhW6B5Jfg9K wHYVhpDfc+2+Q== From: Sasha Levin To: tiwai@suse.de, sashiko-bot@kernel.org Cc: stable@vger.kernel.org Subject: FAILED: patch "[PATCH] ALSA: line6: Handle period elapsed calls outside the locks" failed to apply to 6.6-stable tree Date: Sat, 7 Nov 2026 05:37:22 -0500 Message-ID: <20261107053722-failed-6.6-443ed4edc267@kernel.org> X-Mailer: git-send-email 2.53.0 X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x 443ed4edc2678cc51c5a01e7dffc4c890be40051 # git commit -s git send-email --to '' --in-reply-to '20261107053722-failed-6.6-443ed4edc267@kernel.org' --subject-prefix 'PATCH 6.6.y' 'HEAD^..' Thanks, Sasha ------------------ original commit in Linus's tree ------------------ >From 443ed4edc2678cc51c5a01e7dffc4c890be40051 Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Tue, 20 Oct 2026 13:31:17 +0200 Subject: [PATCH] ALSA: line6: Handle period elapsed calls outside the locks LINE6 driver may call snd_pcm_period_elapsed() for both playback and capture substreams at processing the playback substream, and this may lead to a ABBA deadlock. Move the actual calls of snd_pcm_period_elapsed() outside the locks for avoiding it. The capture period notification at submitting the initial playback URBs (only with the impulse mode) is simply skipped, as it's done in the lock context; it'll be caught up at the next period. Fixes: f56742cc4189 ("ALSA: line6: Add LINE6_CAP_IN_NEEDS_OUT, a void playback stream during capture") Reported-by: Sashiko Closes: https://sashiko.dev/#/bug/linux-5a9de389-e6ea-410d-8322-e74e14152603 Cc: Link: https://patch.msgid.link/20261020113118.234689-1-tiwai@suse.de Signed-off-by: Takashi Iwai --- sound/usb/line6/capture.c | 25 ++++++++++++++++--------- sound/usb/line6/capture.h | 2 +- sound/usb/line6/playback.c | 31 +++++++++++++++++++++---------- 3 files changed, 38 insertions(+), 20 deletions(-) diff --git a/sound/usb/line6/capture.c b/sound/usb/line6/capture.c index 3e1f40d6b481a..17f49f567efbf 100644 --- a/sound/usb/line6/capture.c +++ b/sound/usb/line6/capture.c @@ -126,24 +126,21 @@ void line6_capture_copy(struct snd_line6_pcm *line6pcm, char *fbuf, int fsize) line6pcm->in.pos_done -= runtime->buffer_size; } -void line6_capture_check_period(struct snd_line6_pcm *line6pcm, int length) +/* update the capture position and check whether we need period_elapsed call */ +bool line6_capture_check_period(struct snd_line6_pcm *line6pcm, int length) { - struct snd_pcm_substream *substream = - get_substream(line6pcm, SNDRV_PCM_STREAM_CAPTURE); - line6pcm->in.bytes += length; if (line6pcm->in.bytes >= line6pcm->in.period) { line6pcm->in.bytes %= line6pcm->in.period; - spin_unlock(&line6pcm->in.lock); - snd_pcm_period_elapsed(substream); - spin_lock(&line6pcm->in.lock); + return true; } + return false; } /* * Callback for completed capture URB. */ -static void audio_in_callback(struct urb *urb) +static bool handle_audio_in(struct urb *urb) { int i, index, length = 0, shutdown = 0; struct snd_line6_pcm *line6pcm = (struct snd_line6_pcm *)urb->context; @@ -208,8 +205,18 @@ static void audio_in_callback(struct urb *urb) if (!test_bit(LINE6_STREAM_IMPULSE, &line6pcm->in.running) && test_bit(LINE6_STREAM_PCM, &line6pcm->in.running)) - line6_capture_check_period(line6pcm, length); + return line6_capture_check_period(line6pcm, length); } + + return false; +} + +static void audio_in_callback(struct urb *urb) +{ + struct snd_line6_pcm *line6pcm = (struct snd_line6_pcm *)urb->context; + + if (handle_audio_in(urb)) + snd_pcm_period_elapsed(get_substream(line6pcm, SNDRV_PCM_STREAM_CAPTURE)); } /* open capture callback */ diff --git a/sound/usb/line6/capture.h b/sound/usb/line6/capture.h index 90572dae134ee..628315389efcf 100644 --- a/sound/usb/line6/capture.h +++ b/sound/usb/line6/capture.h @@ -17,7 +17,7 @@ extern const struct snd_pcm_ops snd_line6_capture_ops; extern void line6_capture_copy(struct snd_line6_pcm *line6pcm, char *fbuf, int fsize); -extern void line6_capture_check_period(struct snd_line6_pcm *line6pcm, +extern bool line6_capture_check_period(struct snd_line6_pcm *line6pcm, int length); extern int line6_create_audio_in_urbs(struct snd_line6_pcm *line6pcm); extern int line6_submit_audio_in_all_urbs(struct snd_line6_pcm *line6pcm); diff --git a/sound/usb/line6/playback.c b/sound/usb/line6/playback.c index aa6ddf8746a0a..e93a16f6958e3 100644 --- a/sound/usb/line6/playback.c +++ b/sound/usb/line6/playback.c @@ -136,6 +136,8 @@ static void add_monitor_signal(struct urb *urb_out, unsigned char *signal, /* Find a free URB, prepare audio data, and submit URB. must be called in line6pcm->out.lock context + Returns 1 if snd_pcm_period_elapsed() needs to be called for the + capture stream after releasing the lock, 0 if not, or a negative error */ static int submit_audio_out_urb(struct snd_line6_pcm *line6pcm) { @@ -151,6 +153,7 @@ static int submit_audio_out_urb(struct snd_line6_pcm *line6pcm) line6pcm->properties->rates.rats[0].den * (line6pcm->line6->intervals_per_second / LINE6_ISO_INTERVAL); struct urb *urb_out; + bool capture_period_elapsed = false; index = find_first_zero_bit(&line6pcm->out.active_urbs, line6pcm->line6->iso_buffers); @@ -260,8 +263,9 @@ static int submit_audio_out_urb(struct snd_line6_pcm *line6pcm) urb_out->transfer_buffer, urb_out-> transfer_buffer_length); - line6_capture_check_period(line6pcm, - urb_out->transfer_buffer_length); + capture_period_elapsed = + line6_capture_check_period(line6pcm, + urb_out->transfer_buffer_length); } } else { if (!(line6pcm->line6->properties->capabilities & LINE6_CAP_HWMON) @@ -283,24 +287,26 @@ static int submit_audio_out_urb(struct snd_line6_pcm *line6pcm) dev_err(line6pcm->line6->ifcdev, "URB out #%d submission failed (%d)\n", index, ret); - return 0; + return capture_period_elapsed; } /* Submit all currently available playback URBs. must be called in line6pcm->out.lock context + The capture period notification is skipped here since we can't call + snd_pcm_period_elapsed() in the lock; it'll be caught up at the next one. */ int line6_submit_audio_out_all_urbs(struct snd_line6_pcm *line6pcm) { - int ret = 0, i; + int ret, i; for (i = 0; i < line6pcm->line6->iso_buffers; ++i) { ret = submit_audio_out_urb(line6pcm); if (ret < 0) - break; + return ret; } - return ret; + return 0; } /* @@ -316,6 +322,8 @@ static void audio_out_callback(struct urb *urb) const int bytes_per_frame = line6pcm->properties->bytes_per_channel * line6pcm->properties->playback_hw.channels_max; + bool capture_period_elapsed = false; + bool playback_period_elapsed = false; #if USE_CLEAR_BUFFER_WORKAROUND memset(urb->transfer_buffer, 0, urb->transfer_buffer_length); @@ -358,19 +366,22 @@ static void audio_out_callback(struct urb *urb) shutdown = 1; if (!shutdown) { - submit_audio_out_urb(line6pcm); + capture_period_elapsed = submit_audio_out_urb(line6pcm) > 0; if (test_bit(LINE6_STREAM_PCM, &line6pcm->out.running)) { line6pcm->out.bytes += length; if (line6pcm->out.bytes >= line6pcm->out.period) { line6pcm->out.bytes %= line6pcm->out.period; - spin_unlock(&line6pcm->out.lock); - snd_pcm_period_elapsed(substream); - spin_lock(&line6pcm->out.lock); + playback_period_elapsed = true; } } } spin_unlock_irqrestore(&line6pcm->out.lock, flags); + + if (capture_period_elapsed) + snd_pcm_period_elapsed(get_substream(line6pcm, SNDRV_PCM_STREAM_CAPTURE)); + if (playback_period_elapsed) + snd_pcm_period_elapsed(substream); } /* open playback callback */ -- 2.53.0