Replace prior inline description to prevent future deadlock. Cc: stable@xxxxxxxxxxxxxxx Link: https://lore.kernel.org/r/kwryofzdmjvzkuw6j3clftsxmoolynljztxqwg76hzeo4simnl@jn3eo7pe642q/ Signed-off-by: Edmund Raile <edmund.raile@xxxxxxxxxxxxxx> --- sound/firewire/amdtp-stream.c | 20 ++++++-------------- 1 file changed, 6 insertions(+), 14 deletions(-) diff --git a/sound/firewire/amdtp-stream.c b/sound/firewire/amdtp-stream.c index a07b0452267d..7438999e0510 100644 --- a/sound/firewire/amdtp-stream.c +++ b/sound/firewire/amdtp-stream.c @@ -1857,20 +1857,12 @@ 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)) { - // This function is called in software IRQ context of - // period_work or process context. - // - // When the software IRQ context was scheduled by software IRQ - // context of IT contexts, queued packets were already handled. - // Therefore, no need to flush the queue in buffer furthermore. - // - // When the process context reach here, some packets will be - // already queued in the buffer. These packets should be handled - // immediately to keep better granularity of PCM pointer. - // - // Later, the process context will sometimes schedules software - // IRQ context of the period_work. Then, no need to flush the - // queue by the same reason as described in the above + // 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() if (current_work() != &s->period_work) fw_iso_context_flush_completions(irq_target->context); } -- 2.45.2
