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=1794321726; b=4852FklTQ3c2lkjtifWKl/BMsvLYAnnalZSvgUdnrq/0q9Ysb1TGMfmIIqokp5BAk0gb md0eVPgRcNm6D/44lUIb7P4E5/IIZZi9Ny6VTk+XmTuh5S+s2Z04NARJOuw9NVivJgABU 5i9zBNmM5loM39OTR7AUspkpswKAXdqXyLPV6ISsQ3zjlCWKc44CFPOLnrSGImS5t6oFA ktkGPG66NQwxLgYGPfveeE7h5OigPJmN0LHMyrkEhrhV9IyLnVw2vF79rIPGMqbKygqtX 2Mj9/7u/CfRY+4KGuNZsMjElJpEXjJSv7bIcr6GS0AgTlEpxpLJ8oWZe24SmvA3GEjA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794321726; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=6bmCKRzezAcmzlUT0DIyvWWeIi7yBaMLn9fmTZ9C/0A=; b=yKwPb99CRTEpvmrMWRFRNqmZ1Er+Loo/bd7QGcok8D00/9TDBIkmQRrGHJDUaLUFLO9n JBwK6c4nemNtVVS0ncVdMH7LVcaO4bVi4DwiCyvzhkusup4t30UMfEpdfeb55EeULrNmB Log67I2AvQ4qP0GsZ0mmsqUkdUK1jtIRRlebc6zKMgcW9YSEdLZSYIejt1RUIec7FeDDU /Dzg/70e0JWNvcu2zodKQG/RilcZNxThp5D28sz3uLf4P8BwHbPhfQrVsPwUiZiXdpeKf vYPLoAbwNxsugrP3jYBckcpnjfg1S9sLQaWI0vehoj8VCAZKvc60Sasx1Yc0UbHDLkQ== 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=V7OcrMMt; 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 D2CA360A382D for ; Tue, 10 Nov 2026 14:42:05 +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=V7OcrMMt Received: by smtp.kernel.org (Postfix) with ESMTPSA id 212AF1F008A2; Tue, 10 Nov 2026 14:42:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794321725; bh=6bmCKRzezAcmzlUT0DIyvWWeIi7yBaMLn9fmTZ9C/0A=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=V7OcrMMtSW6it9rOXR7yvaVAUq6+2LnBu2bXkudB5y7SyFN7FzotugbLy1i32umxO O2ztMssqDxm1fvB4F3gGiAT9lnsQ8n9nZ5IW4Ml8aQutOhPUzADiXweEVU6k/N2RcL k2UY9remlIfXXGeA5TGU58eLF5pAB4nTqvTraMa1uvmwi81KQUB4MDaQdebr578wZP rQM0lko5Ddg+f3s6AH/cMOIBMef447EqrLjfRmxxa2mcsKYsZAG4JTlr+LjR51yRPr l87GnDO4zaPPIq7ThY846nyGXqgtA3B1PtKT1RFplVFm4sILwtkhTT39cP/4R6XY7a C2R/AQzz2IRVw== From: Sasha Levin To: stable@vger.kernel.org Cc: Takashi Iwai , Sashiko , Sasha Levin Subject: [PATCH 6.12.y 2/2] ALSA: line6: Handle period elapsed calls outside the locks Date: Tue, 10 Nov 2026 09:42:03 -0500 Message-ID: <20261110144156.1950251-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261110144156.1950251-1-sashal@kernel.org> References: <20261107052438-failed-6.12-443ed4edc267@kernel.org> <20261110144156.1950251-1-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 dde52454ec65e..f59ec9c4a1a52 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 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 2e70ca5456c5a..495a983a0c51f 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