diff options
Diffstat (limited to 'sound/firewire/amdtp-stream.c')
| -rw-r--r-- | sound/firewire/amdtp-stream.c | 34 |
1 files changed, 27 insertions, 7 deletions
diff --git a/sound/firewire/amdtp-stream.c b/sound/firewire/amdtp-stream.c index c827d7d8d800..c72b2a754775 100644 --- a/sound/firewire/amdtp-stream.c +++ b/sound/firewire/amdtp-stream.c @@ -615,6 +615,22 @@ static void update_pcm_pointers(struct amdtp_stream *s, // The program in user process should periodically check the status of intermediate // buffer associated to PCM substream to process PCM frames in the buffer, instead // of receiving notification of period elapsed by poll wait. + // + // Use another work item for period elapsed event to prevent the following AB/BA + // deadlock: + // + // thread 1 thread 2 + // ================================= ================================= + // A.work item (process) pcm ioctl (process) + // v v + // process_rx_packets() B.PCM stream lock + // process_tx_packets() v + // v callbacks in snd_pcm_ops + // update_pcm_pointers() v + // snd_pcm_elapsed() fw_iso_context_flush_completions() + // snd_pcm_stream_lock_irqsave() disable_work_sync() + // v v + // wait until release of B wait until A exits if (!pcm->runtime->no_period_wakeup) queue_work(system_highpri_wq, &s->period_work); } @@ -1055,8 +1071,15 @@ static void generate_rx_packet_descs(struct amdtp_stream *s, struct pkt_desc *de static inline void cancel_stream(struct amdtp_stream *s) { + struct work_struct *work = current_work(); + s->packet_index = -1; - if (in_softirq()) + + // Detect work items for any isochronous context. The work item for pcm_period_work() + // should be avoided since the call of snd_pcm_period_elapsed() can reach via + // snd_pcm_ops.pointer() under acquiring PCM stream(group) lock and causes dead lock at + // snd_pcm_stop_xrun(). + if (work && work != &s->period_work) amdtp_stream_pcm_abort(s); WRITE_ONCE(s->pcm_buffer_pointer, SNDRV_PCM_POS_XRUN); } @@ -1856,12 +1879,9 @@ unsigned long amdtp_domain_stream_pcm_pointer(struct amdtp_domain *d, struct amdtp_stream *irq_target = d->irq_target; if (irq_target && amdtp_stream_running(irq_target)) { - // use wq to prevent AB/BA deadlock competition for - // substream lock: - // fw_iso_context_flush_completions() acquires - // lock by ohci_flush_iso_completions(), - // amdtp-stream process_rx_packets() attempts to - // acquire same lock by snd_pcm_elapsed() + // The work item to call snd_pcm_period_elapsed() can reach here by the call of + // snd_pcm_ops.pointer(), however less packets would be available then. Therefore + // the following call is just for user process contexts. if (current_work() != &s->period_work) fw_iso_context_flush_completions(irq_target->context); } |