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Wed, 11 Nov 2026 16:47:24 -0800 (PST) Received: from localhost.localdomain ([183.96.175.225]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-1b3b5b2eeffsm20672163c88.9.2026.11.11.16.47.21 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Wed, 11 Nov 2026 16:47:24 -0800 (PST) From: Joonho Lee To: linux-sound@vger.kernel.org Cc: tiwai@suse.com, perex@perex.cz, anton.yakovlev@opensynergy.com, mst@redhat.com, virtualization@lists.linux.dev, linux-kernel@vger.kernel.org, corbet@lwn.net, skhan@linuxfoundation.org, rdunlap@infradead.org, linux-doc@vger.kernel.org, Joonho Lee Subject: [PATCH v27 04/17] ALSA: pcm: notify drivers after linked prepare completes Date: Thu, 12 Nov 2026 09:46:51 +0900 Message-ID: <20261112004704.49758-5-mynameisjune111@gmail.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20261112004704.49758-1-mynameisjune111@gmail.com> References: <20261112004704.49758-1-mynameisjune111@gmail.com> X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit A linked prepare can finish one member before another member's driver prepare or reset fails. Drivers that admit transfers after their own prepare callback can then accept an ACK while the group action is still incomplete. Add an optional prepare_complete callback. After all sleeping prepare and reset actions have succeeded, take the group and member PCM locks, publish every PREPARED state, and notify opted-in drivers before releasing those locks. Keep the buffer locks and access gates held throughout the operation. A concurrent DROP observes the group before or after this commit point. On a driver error, notify only the attempted prefix, including the failing member. On any revoked prepare, opted-in members in the affected prefix or group return to SETUP. Preserve DISCONNECTED members and keep SUSPENDED members suspended, but set both saved suspended-state fields to SETUP so a later prepare can recover. Leave unreached members untouched after a driver error. Preflight failures have no completion callback. A successful driver action canceled by a terminal state returns -ESTRPIPE or -EBADFD, respectively. A driver error keeps its original return value. DISCONNECTED takes precedence when a linked group contains both terminal states. Do not generate a stop-timer event while closing prepare admission. Ordinary legacy drivers keep their existing successful preparation and pointer rebasing. The new callback runs with the group and member locks held and must neither sleep nor acquire another PCM stream lock. Assisted-by: LLM Signed-off-by: Joonho Lee --- include/sound/pcm.h | 18 +++++ sound/core/pcm_native.c | 162 +++++++++++++++++++++++++++++++++++++++++------ 2 files changed, 160 insertions(+), 20 deletions(-) diff --git a/include/sound/pcm.h b/include/sound/pcm.h --- a/include/sound/pcm.h +++ b/include/sound/pcm.h @@ -77,6 +77,24 @@ unsigned long offset); int (*mmap)(struct snd_pcm_substream *substream, struct vm_area_struct *vma); int (*ack)(struct snd_pcm_substream *substream); + /* + * Optional prepare completion notification. Called while the core holds + * all linked PCM stream locks, after prepare/reset actions succeed or stop + * at the first error. On success, the core publishes PREPARED for every + * member before calling this with true. If any member is DISCONNECTED or + * SUSPENDED, opted-in members in the affected group receive false. + * Nonterminal opted-in members become SETUP. DISCONNECTED members remain + * DISCONNECTED. SUSPENDED members remain SUSPENDED with both saved + * suspended-state fields set to SETUP. On a driver failure, called with false + * for opted-in members whose action ran, including the failing member. + * Members not reached and pre-action failures receive no callback. Standalone + * RESET does not call this callback. It must not sleep or acquire another PCM + * stream lock. + * A terminal-state cancellation returns -EBADFD for DISCONNECTED or + * -ESTRPIPE for SUSPENDED. + */ + void (*prepare_complete)(struct snd_pcm_substream *substream, + bool success); /* * Optional RESET operation, also used after a successful prepare. * Called with this substream's PCM lock held; atomic streams must not diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c --- a/sound/core/pcm_native.c +++ b/sound/core/pcm_native.c @@ -1310,6 +1310,10 @@ snd_pcm_state_t state); void (*post_action)(struct snd_pcm_substream *substream, snd_pcm_state_t state); + int (*finish_action)(struct snd_pcm_substream *substream, + snd_pcm_state_t state, bool success, + struct snd_pcm_substream *failed_substream, + bool stream_lock); }; /* @@ -1350,12 +1354,19 @@ ops->undo_action(s1, state); } } + if (ops->finish_action) { + ops->finish_action(substream, state, false, s, + stream_lock); + } s = NULL; /* unlock all */ goto _unlock; } } - snd_pcm_group_for_each_entry(s, substream) { - ops->post_action(s, state); + if (ops->finish_action) { + res = ops->finish_action(substream, state, true, NULL, stream_lock); + } else { + snd_pcm_group_for_each_entry(s, substream) + ops->post_action(s, state); } _unlock: /* unlock streams */ @@ -1379,7 +1390,8 @@ */ static int snd_pcm_action_single(const struct action_ops *ops, struct snd_pcm_substream *substream, - snd_pcm_state_t state) + snd_pcm_state_t state, + bool stream_lock) { int res; @@ -1387,10 +1399,19 @@ if (res < 0) return res; res = ops->do_action(substream, state); - if (res == 0) - ops->post_action(substream, state); - else if (ops->undo_action) - ops->undo_action(substream, state); + if (res == 0) { + if (ops->finish_action) + res = ops->finish_action(substream, state, true, NULL, + stream_lock); + else + ops->post_action(substream, state); + } else { + if (ops->undo_action) + ops->undo_action(substream, state); + if (ops->finish_action) + ops->finish_action(substream, state, false, substream, + stream_lock); + } return res; } @@ -1469,7 +1490,7 @@ if (group) res = snd_pcm_action_group(ops, substream, state, true); else - res = snd_pcm_action_single(ops, substream, state); + res = snd_pcm_action_single(ops, substream, state, true); snd_pcm_group_unref(group, substream); return res; } @@ -1501,7 +1522,7 @@ if (snd_pcm_stream_linked(substream)) res = snd_pcm_action_group(ops, substream, state, false); else - res = snd_pcm_action_single(ops, substream, state); + res = snd_pcm_action_single(ops, substream, state, false); snd_pcm_buffer_access_unlock(substream->runtime); return res; } @@ -1660,7 +1681,7 @@ int snd_pcm_drain_done(struct snd_pcm_substream *substream) { return snd_pcm_action_single(&snd_pcm_action_stop, substream, - SNDRV_PCM_STATE_SETUP); + SNDRV_PCM_STATE_SETUP, true); } /** @@ -2063,9 +2084,12 @@ static int snd_pcm_pre_prepare(struct snd_pcm_substream *substream, snd_pcm_state_t state) { - snd_pcm_state_t cur_state = snd_pcm_get_state(substream); + struct snd_pcm_runtime *runtime = substream->runtime; + snd_pcm_state_t cur_state; int f_flags = state; + guard(pcm_stream_lock_irq)(substream); + cur_state = runtime->state; if (cur_state == SNDRV_PCM_STATE_OPEN || cur_state == SNDRV_PCM_STATE_DISCONNECTED) return -EBADFD; @@ -2089,20 +2113,118 @@ return snd_pcm_reset_substream(substream, true); } -static void snd_pcm_post_prepare(struct snd_pcm_substream *substream, - snd_pcm_state_t state) -{ - struct snd_pcm_runtime *runtime = substream->runtime; - /* The reset callback path already completed this rebase under the lock. */ - if (!substream->ops->reset) - runtime->control->appl_ptr = runtime->status->hw_ptr; - snd_pcm_set_state(substream, SNDRV_PCM_STATE_PREPARED); +static int snd_pcm_finish_prepare(struct snd_pcm_substream *substream, + snd_pcm_state_t state, bool success, + struct snd_pcm_substream *failed_substream, + bool stream_lock) +{ + struct snd_pcm_substream *s; + struct snd_pcm_group *group = NULL; + bool cancel = false; + int cancel_err = 0; + int depth = 1; + + if (!stream_lock) { + snd_pcm_stream_lock_irq(substream); + group = snd_pcm_stream_group_ref(substream); + if (group) { + snd_pcm_group_for_each_entry(s, substream) { + if (s == substream) + continue; + if (s->pcm->nonatomic) + mutex_lock_nested(&s->self_group.mutex, depth); + else + spin_lock_nested(&s->self_group.lock, depth); + depth++; + } + } + } + + /* Preserve terminal states instead of publishing a partial group commit. */ + snd_pcm_group_for_each_entry(s, substream) { + struct snd_pcm_runtime *runtime = s->runtime; + + if (runtime->state == SNDRV_PCM_STATE_DISCONNECTED) { + cancel = true; + cancel_err = -EBADFD; + } else if (runtime->state == SNDRV_PCM_STATE_SUSPENDED) { + cancel = true; + if (!cancel_err) + cancel_err = -ESTRPIPE; + } + if (!success && s == failed_substream) + break; + } + + if (success && !cancel) { + snd_pcm_group_for_each_entry(s, substream) { + struct snd_pcm_runtime *runtime = s->runtime; + + /* The reset callback path already completed this rebase. */ + if (!s->ops->reset) + runtime->control->appl_ptr = runtime->status->hw_ptr; + __snd_pcm_set_state(runtime, SNDRV_PCM_STATE_PREPARED); + } + } else if (!success || cancel) { + snd_pcm_group_for_each_entry(s, substream) { + struct snd_pcm_runtime *runtime = s->runtime; + + if (s->ops->prepare_complete) { + if (runtime->state == SNDRV_PCM_STATE_SUSPENDED) { + runtime->suspended_state = + SNDRV_PCM_STATE_SETUP; + runtime->status->suspended_state = + SNDRV_PCM_STATE_SETUP; + } else if (runtime->state != + SNDRV_PCM_STATE_DISCONNECTED && + runtime->state != SNDRV_PCM_STATE_SETUP) { + __snd_pcm_set_state(runtime, + SNDRV_PCM_STATE_SETUP); + } + } + if (!success && s == failed_substream) + break; + } + } + + if (!success || cancel) { + snd_pcm_group_for_each_entry(s, substream) { + wake_up(&s->runtime->sleep); + wake_up(&s->runtime->tsleep); + if (!success && s == failed_substream) + break; + } + } + + /* Publish all states before any driver observes completion. */ + snd_pcm_group_for_each_entry(s, substream) { + if (s->ops->prepare_complete) + s->ops->prepare_complete(s, success && !cancel); + if (!success && s == failed_substream) + break; + } + + if (!stream_lock) { + if (group) { + snd_pcm_group_for_each_entry(s, substream) { + if (s == substream) + continue; + if (s->pcm->nonatomic) + mutex_unlock(&s->self_group.mutex); + else + spin_unlock(&s->self_group.lock); + } + snd_pcm_group_unref(group, substream); + } + snd_pcm_stream_unlock_irq(substream); + } + return success && cancel ? cancel_err : 0; } static const struct action_ops snd_pcm_action_prepare = { .pre_action = snd_pcm_pre_prepare, .do_action = snd_pcm_do_prepare, - .post_action = snd_pcm_post_prepare + .finish_action = snd_pcm_finish_prepare }; /**