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=1794322159; b=3g1eyCZRk3z/I8X95tqEoOfXKcrNEcIhFjKJtcSBdIpi8XBoof8SFJvB1doapIh9onFb ND+OqAyYw4bbSj7wsRVZ2U0WjDDYasBAueCbEur2dSrldw1sq7G7CO9O7HXaz1A016/tg XiWyzAME+tVaDTrEI6xUgJbdp66HK75s9n6o8/Z573pzvp/NIvBTnU9IOdxE2LQNLKNZn omni4Rbx8dX8CY4f1cI+tSqw5Qd6JCF8RNhpGpjRO9WKCq9eh8fzhTfn/bmOY5XxJRfGD SBfwn1t7WnO1crj8vgt1JBI06VB4PGp9XhnYXCJLTqGiGV2wx+BrrzJVJTR9IuecVrw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794322159; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=3ZwmCEP1K9h2s47idUb/2Sz7g0zmF+Q5M9NcHhUqkt8=; b=YMsyUYn6aHMErnLNLSbt9UORrsNlGX47Cf5dczEMjIslf6bTGVq1FdENH05XJf54rBUE DVLqEyJu1jXrlpP45crOqUvlXE73xtxEOlAPE6jELOlUZXrJ7ld4WDL7InkGV4y8GhVX8 vOxRNoDGbE3tq2zYhPj2iO+xseSjl5Bh7XxLLPGPwHUfiCYxWUBruhXqbwdEQBM5XzFCd M3LWZHvM8E8rM8b+YtFEpEFb2sPWrAbKgDxufSrTXbCnBP9KvxFhw5FHrwarqcSPY1tWu tLwBEbe8201HWccZmYXbPw796q9R02sHMN7IYGJiiljjwmN2LUJlR2WvVVxAmN0KmNg== 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="YCf+FV8/"; 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 1DCF6606A31C for ; Tue, 10 Nov 2026 14:49:18 +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=YCf+FV8/ Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2CB2E1F008A2; Tue, 10 Nov 2026 14:49:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794322158; bh=3ZwmCEP1K9h2s47idUb/2Sz7g0zmF+Q5M9NcHhUqkt8=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=YCf+FV8/UPHgwvpvdRh9vTo298rqGoj3uBxzMn+PX3KgrzyZuxHYoS5ceSoowOmlm ADDBEJj84OSZ2cMlCaO3kLi40P7CQu/oAEDGq+JWJ/ag6c0IW+6oZ/qJnJ6rDNGJQr KXAVa4pqEm/Ge7GsTHhqvjflIojb/Mkb54PrFJmCxsULfeEX18Uum38VH3Q/Uuwk+X lwCwxkWapREazHjZI69LhBQfzR2iyj0c//5CWYiXR3DoWv6B5OrSnhPfF6Nt5hMcv/ yjkyvgkWGQiu0rOYssravcWU7gpmMXwdaG8nrowb7yHK80RWF7ZmDRgoijbrTuQ8pW dgurC48GdE3dA== From: Sasha Levin To: stable@vger.kernel.org Cc: Takashi Iwai , Sashiko , Sasha Levin Subject: [PATCH 6.6.y 2/2] ALSA: line6: Handle period elapsed calls outside the locks Date: Tue, 10 Nov 2026 09:49:16 -0500 Message-ID: <20261110144908.1985531-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261110144908.1985531-1-sashal@kernel.org> References: <20261107053722-failed-6.6-443ed4edc267@kernel.org> <20261110144908.1985531-1-sashal@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-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 Signed-off-by: Sasha Levin --- 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 f26cb35446cf9..17c00d8912d9e 100644 --- a/sound/usb/line6/capture.c +++ b/sound/usb/line6/capture.c @@ -137,24 +137,21 @@ 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; @@ -219,8 +216,18 @@ 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 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