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=1794323441; b=aN+hp3SBu5RNjBspKceHF5movIfsQaexh/cYye4srJvhcicv5YCUlWmpuwJ1SIN9K3Dg it/qdFvd/sseUVNnBncvlAPtvEwRq3rU6+NInOMZHLqStVFunjeTV1ORzBwDRSq+4B7qW GaBSyySe4i98huTEo3i29PqdXDAQXAo/89EJyRBySqMaZajYYupCtYu/GDih8570lYhcb x0JyRsTPKq07augcDJ61n6sx5eSSQ/+O85olUu8BZNc2pyrx8Fqq+oCF2PDQf5PqbStg8 Q5bLrqkll+xH+mLMi2XPbAGuGw2bDV9Q4D/fsK8tlgRjmhTovPVFRQdnhPEW4c+Zj+w== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794323441; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Type: Content-Transfer-Encoding; bh=rqUneXZdPuTARhu0FitGmqy/56ivQBdT+kb0SpAs+H4=; b=cHuSL1wgqhUADcWS+BMEebErAaa2Im02x9xjlF+8//e3WqDe2V8NhVujEqn+FiXc7q1+ XqkcQRgsQnO1s2dupXqZfPvHxdinHfUcaQCj6L7RaJfsOSKl0wxMhi0619EFGM7e3HanG XlZEPUQ5iT/UdAYSGMM7eH834LufP8YPemZCNR1p7SMYJLvKJ+QTvigS7OPBrA8hLxKUz S0jlqYhvFpn04bicJCdN47p28deDz7G6XZnzYhO8b7OUXm8c6DYhjVmX3i6bAshhwn1tZ j1wzIn+Ms+Nu39I/hQOit9DUVKnwwsETEwcKoZMwcrUMp/eMpTOZZd92w9EvlpQ1m2A== 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=Si4SP6tt; 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 1A53D606A320 for ; Tue, 10 Nov 2026 15:10:40 +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=Si4SP6tt Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1C9BF1F0089F; Tue, 10 Nov 2026 15:10:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794323440; bh=rqUneXZdPuTARhu0FitGmqy/56ivQBdT+kb0SpAs+H4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Si4SP6tt/QQ80ij4Ui+pJ6MnRH75J7gHsiyZ5BgL3GafiVqM8cTgjBLPPG/DiPV7R mPDs9dg/30FARZ/hjorh2FlgiNLFvwuKK6IxvVl+iBLzJ6Ys9+RD+KXA6VS+Jkzbpg 6lq/VukQktTmldCwKmTISYokDi18NiIfluYxVpzNyiHTEtq5W+WdA2AWO+bYa+iTHR n14l55aLjlZSO9LeH7CC1Xc7YqIkOOi0mYWiyKSTUYL5Qpx5dvMjr2E+8/eimg441b fBOYZc3D2wkxAD2DxShUBujiGRC2Xx3NoZ0MRN/J+Rxyc+LcyBKaGPBO/lK4QlLnXP Ceiijn3gUFlmQ== From: Sasha Levin To: stable@vger.kernel.org Cc: Takashi Iwai , Sashiko , Sasha Levin Subject: [PATCH 6.1.y] ALSA: line6: Handle period elapsed calls outside the locks Date: Tue, 10 Nov 2026 10:10:37 -0500 Message-ID: <20261110151020.2007125-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261107055207-failed-6.1-443ed4edc267@kernel.org> References: <20261107055207-failed-6.1-443ed4edc267@kernel.org> 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 From: Takashi Iwai [ Upstream commit 443ed4edc2678cc51c5a01e7dffc4c890be40051 ] 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 [ sashal: Replaced upstream’s helper/wrapper split and automatic lock cleanup with a single capture callback using explicit unlocking and a local notification flag. ] Signed-off-by: Sasha Levin --- sound/usb/line6/capture.c | 17 +++++++++-------- sound/usb/line6/capture.h | 2 +- sound/usb/line6/playback.c | 31 +++++++++++++++++++++---------- 3 files changed, 31 insertions(+), 19 deletions(-) diff --git a/sound/usb/line6/capture.c b/sound/usb/line6/capture.c index e77ef16c792f0..2f7490c8693fa 100644 --- a/sound/usb/line6/capture.c +++ b/sound/usb/line6/capture.c @@ -137,18 +137,15 @@ 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; } /* @@ -158,6 +155,7 @@ static void audio_in_callback(struct urb *urb) { int i, index, length = 0, shutdown = 0; unsigned long flags; + bool capture_period_elapsed = false; struct snd_line6_pcm *line6pcm = (struct snd_line6_pcm *)urb->context; @@ -221,10 +219,13 @@ 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); + capture_period_elapsed = line6_capture_check_period(line6pcm, length); } spin_unlock_irqrestore(&line6pcm->in.lock, flags); + + if (capture_period_elapsed) + 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 20e05a5eceb4f..5ae1745261e50 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 0da1998dd5add..deb313486ee78 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