On 06/06/2011 11:05 AM, Takashi Iwai wrote:
At Sun, 05 Jun 2011 11:57:57 +0200, Jörn Nettingsmeier wrote:
hi *!
while we were trying to debug the midi-related xruns in the current driver, i came across what looks like an unrelated locking bug to me:
static int snd_hdspm_midi_input_read (struct hdspm_midi *hmidi) ... spin_lock_irqsave (&hmidi->lock, flags);<--------------- n_pending = snd_hdspm_midi_input_available (hmidi->hdspm, hmidi->id); ... hmidi->pending = 0;
hmidi->hdspm->control_register |= hmidi->ie;<------- !!! hdspm_write(hmidi->hdspm, HDSPM_controlRegister, hmidi->hdspm->control_register); spin_unlock_irqrestore (&hmidi->lock, flags);<--------- return snd_hdspm_midi_output_write (hmidi);}
if i understand this whole business correctly, we should be holding the hdspm lock here, not the hmidi one.
please review the attached patch and apply if you think it's ok.
Well, it's a wrong lock for snd_hdspm_midi_input_available(). So you'll need to lock twice, either once unlock and lock another or nested. Re-locking would be less messy in this case, I suppose.
ok, here's a revised patch. has been running for 20 or so hours without problems, although the load was light most of the time.
please consider for inclusion.
best,
jörn