From e9ba389c5ffc4dd29dfe17e00e48877302111135 Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Wed, 15 Aug 2012 12:32:00 +0200 Subject: ALSA: usb-audio: Fix scheduling-while-atomic bug in PCM capture stream A PCM capture stream on usb-audio causes a scheduling-while-atomic BUG, as reported in the bugzilla entry below. It's because snd_usb_endpoint_start() is called at first at trigger START for a capture stream, and this function contains the left-over EP deactivation codes. The problem doesn't happen for a playback stream because the function is called at PCM prepare time, which can sleep. This patch fixes the BUG by moving the EP deactivation code into the PCM prepare callback. Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=46011 Cc: [v3.5+] Signed-off-by: Takashi Iwai --- sound/usb/endpoint.c | 4 ---- 1 file changed, 4 deletions(-) (limited to 'sound/usb/endpoint.c') diff --git a/sound/usb/endpoint.c b/sound/usb/endpoint.c index 0f647d22cb4a..c41181202688 100644 --- a/sound/usb/endpoint.c +++ b/sound/usb/endpoint.c @@ -821,10 +821,6 @@ int snd_usb_endpoint_start(struct snd_usb_endpoint *ep) if (++ep->use_count != 1) return 0; - /* just to be sure */ - deactivate_urbs(ep, 0, 1); - wait_clear_urbs(ep); - ep->active_mask = 0; ep->unlink_mask = 0; ep->phase = 0; -- cgit v1.2.3 From 015618b902ae8e28705b7af9b4668615fea48ddd Mon Sep 17 00:00:00 2001 From: Daniel Mack Date: Wed, 29 Aug 2012 13:17:05 +0200 Subject: ALSA: snd-usb: Fix URB cancellation at stream start Commit e9ba389c5 ("ALSA: usb-audio: Fix scheduling-while-atomic bug in PCM capture stream") fixed a scheduling-while-atomic bug that happened when snd_usb_endpoint_start was called from the trigger callback, which is an atmic context. However, the patch breaks the idea of the endpoints reference counting, which is the reason why the driver has been refactored lately. Revert that commit and let snd_usb_endpoint_start() take care of the URB cancellation again. As this function is called from both atomic and non-atomic context, add a flag to denote whether the function may sleep. Signed-off-by: Daniel Mack Cc: stable@kernel.org [3.5+] Signed-off-by: Takashi Iwai --- sound/usb/endpoint.c | 11 +++++++++-- sound/usb/endpoint.h | 2 +- sound/usb/pcm.c | 13 +++++-------- 3 files changed, 15 insertions(+), 11 deletions(-) (limited to 'sound/usb/endpoint.c') diff --git a/sound/usb/endpoint.c b/sound/usb/endpoint.c index c41181202688..b896c5559524 100644 --- a/sound/usb/endpoint.c +++ b/sound/usb/endpoint.c @@ -799,7 +799,9 @@ int snd_usb_endpoint_set_params(struct snd_usb_endpoint *ep, /** * snd_usb_endpoint_start: start an snd_usb_endpoint * - * @ep: the endpoint to start + * @ep: the endpoint to start + * @can_sleep: flag indicating whether the operation is executed in + * non-atomic context * * A call to this function will increment the use count of the endpoint. * In case it is not already running, the URBs for this endpoint will be @@ -809,7 +811,7 @@ int snd_usb_endpoint_set_params(struct snd_usb_endpoint *ep, * * Returns an error if the URB submission failed, 0 in all other cases. */ -int snd_usb_endpoint_start(struct snd_usb_endpoint *ep) +int snd_usb_endpoint_start(struct snd_usb_endpoint *ep, int can_sleep) { int err; unsigned int i; @@ -821,6 +823,11 @@ int snd_usb_endpoint_start(struct snd_usb_endpoint *ep) if (++ep->use_count != 1) return 0; + /* just to be sure */ + deactivate_urbs(ep, 0, can_sleep); + if (can_sleep) + wait_clear_urbs(ep); + ep->active_mask = 0; ep->unlink_mask = 0; ep->phase = 0; diff --git a/sound/usb/endpoint.h b/sound/usb/endpoint.h index ee2723fb174f..a8e60c1408e5 100644 --- a/sound/usb/endpoint.h +++ b/sound/usb/endpoint.h @@ -13,7 +13,7 @@ int snd_usb_endpoint_set_params(struct snd_usb_endpoint *ep, struct audioformat *fmt, struct snd_usb_endpoint *sync_ep); -int snd_usb_endpoint_start(struct snd_usb_endpoint *ep); +int snd_usb_endpoint_start(struct snd_usb_endpoint *ep, int can_sleep); void snd_usb_endpoint_stop(struct snd_usb_endpoint *ep, int force, int can_sleep, int wait); int snd_usb_endpoint_activate(struct snd_usb_endpoint *ep); diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c index 62ec808ed792..1546577ae458 100644 --- a/sound/usb/pcm.c +++ b/sound/usb/pcm.c @@ -212,7 +212,7 @@ int snd_usb_init_pitch(struct snd_usb_audio *chip, int iface, } } -static int start_endpoints(struct snd_usb_substream *subs) +static int start_endpoints(struct snd_usb_substream *subs, int can_sleep) { int err; @@ -225,7 +225,7 @@ static int start_endpoints(struct snd_usb_substream *subs) snd_printdd(KERN_DEBUG "Starting data EP @%p\n", ep); ep->data_subs = subs; - err = snd_usb_endpoint_start(ep); + err = snd_usb_endpoint_start(ep, can_sleep); if (err < 0) { clear_bit(SUBSTREAM_FLAG_DATA_EP_STARTED, &subs->flags); return err; @@ -239,7 +239,7 @@ static int start_endpoints(struct snd_usb_substream *subs) snd_printdd(KERN_DEBUG "Starting sync EP @%p\n", ep); ep->sync_slave = subs->data_endpoint; - err = snd_usb_endpoint_start(ep); + err = snd_usb_endpoint_start(ep, can_sleep); if (err < 0) { clear_bit(SUBSTREAM_FLAG_SYNC_EP_STARTED, &subs->flags); return err; @@ -544,13 +544,10 @@ static int snd_usb_pcm_prepare(struct snd_pcm_substream *substream) subs->last_frame_number = 0; runtime->delay = 0; - /* clear the pending deactivation on the target EPs */ - deactivate_endpoints(subs); - /* for playback, submit the URBs now; otherwise, the first hwptr_done * updates for all URBs would happen at the same time when starting */ if (subs->direction == SNDRV_PCM_STREAM_PLAYBACK) - return start_endpoints(subs); + return start_endpoints(subs, 1); return 0; } @@ -1175,7 +1172,7 @@ static int snd_usb_substream_capture_trigger(struct snd_pcm_substream *substream switch (cmd) { case SNDRV_PCM_TRIGGER_START: - err = start_endpoints(subs); + err = start_endpoints(subs, 0); if (err < 0) return err; -- cgit v1.2.3 From 245baf983cc39524cce39c24d01b276e6e653c9e Mon Sep 17 00:00:00 2001 From: Daniel Mack Date: Thu, 30 Aug 2012 18:52:30 +0200 Subject: ALSA: snd-usb: fix calls to next_packet_size In order to support devices with implicit feedback streaming models, packet sizes are now stored with each individual urb, and the PCM handling code which fills the buffers purely relies on the size fields now. However, calling snd_usb_audio_next_packet_size() for all possible packets in an URB at once, prior to letting the PCM code do its job does in fact not lead to the same behaviour than what the old code did: The PCM code will break its loop once a period boundary is reached, consequently using up less packets that it really could. As snd_usb_audio_next_packet_size() implements a feedback mechanism to the endpoints phase accumulator, the number of calls to that function matters, and when called too often, the data rate runs out of bounds. Fix this by making the next_packet function public, and call it from the PCM code as before if the packet data sizes are not defined. Signed-off-by: Daniel Mack Cc: stable@kernel.org [v3.5+] Signed-off-by: Takashi Iwai --- sound/usb/endpoint.c | 13 +------------ sound/usb/endpoint.h | 1 + sound/usb/pcm.c | 7 ++++++- 3 files changed, 8 insertions(+), 13 deletions(-) (limited to 'sound/usb/endpoint.c') diff --git a/sound/usb/endpoint.c b/sound/usb/endpoint.c index b896c5559524..d6e2bb49c59c 100644 --- a/sound/usb/endpoint.c +++ b/sound/usb/endpoint.c @@ -141,7 +141,7 @@ int snd_usb_endpoint_implict_feedback_sink(struct snd_usb_endpoint *ep) * * For implicit feedback, next_packet_size() is unused. */ -static int next_packet_size(struct snd_usb_endpoint *ep) +int snd_usb_endpoint_next_packet_size(struct snd_usb_endpoint *ep) { unsigned long flags; int ret; @@ -177,15 +177,6 @@ static void retire_inbound_urb(struct snd_usb_endpoint *ep, ep->retire_data_urb(ep->data_subs, urb); } -static void prepare_outbound_urb_sizes(struct snd_usb_endpoint *ep, - struct snd_urb_ctx *ctx) -{ - int i; - - for (i = 0; i < ctx->packets; ++i) - ctx->packet_size[i] = next_packet_size(ep); -} - /* * Prepare a PLAYBACK urb for submission to the bus. */ @@ -370,7 +361,6 @@ static void snd_complete_urb(struct urb *urb) goto exit_clear; } - prepare_outbound_urb_sizes(ep, ctx); prepare_outbound_urb(ep, ctx); } else { retire_inbound_urb(ep, ctx); @@ -857,7 +847,6 @@ int snd_usb_endpoint_start(struct snd_usb_endpoint *ep, int can_sleep) goto __error; if (usb_pipeout(ep->pipe)) { - prepare_outbound_urb_sizes(ep, urb->context); prepare_outbound_urb(ep, urb->context); } else { prepare_inbound_urb(ep, urb->context); diff --git a/sound/usb/endpoint.h b/sound/usb/endpoint.h index a8e60c1408e5..cbbbdf226d66 100644 --- a/sound/usb/endpoint.h +++ b/sound/usb/endpoint.h @@ -21,6 +21,7 @@ int snd_usb_endpoint_deactivate(struct snd_usb_endpoint *ep); void snd_usb_endpoint_free(struct list_head *head); int snd_usb_endpoint_implict_feedback_sink(struct snd_usb_endpoint *ep); +int snd_usb_endpoint_next_packet_size(struct snd_usb_endpoint *ep); void snd_usb_handle_sync_urb(struct snd_usb_endpoint *ep, struct snd_usb_endpoint *sender, diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c index 5ceb8f1d63fb..e80b6687f43a 100644 --- a/sound/usb/pcm.c +++ b/sound/usb/pcm.c @@ -1029,6 +1029,7 @@ static void prepare_playback_urb(struct snd_usb_substream *subs, struct urb *urb) { struct snd_pcm_runtime *runtime = subs->pcm_substream->runtime; + struct snd_usb_endpoint *ep = subs->data_endpoint; struct snd_urb_ctx *ctx = urb->context; unsigned int counts, frames, bytes; int i, stride, period_elapsed = 0; @@ -1040,7 +1041,11 @@ static void prepare_playback_urb(struct snd_usb_substream *subs, urb->number_of_packets = 0; spin_lock_irqsave(&subs->lock, flags); for (i = 0; i < ctx->packets; i++) { - counts = ctx->packet_size[i]; + if (ctx->packet_size[i]) + counts = ctx->packet_size[i]; + else + counts = snd_usb_endpoint_next_packet_size(ep); + /* set up descriptor */ urb->iso_frame_desc[i].offset = frames * stride; urb->iso_frame_desc[i].length = counts * stride; -- cgit v1.2.3