Messages in this thread | | | From | "Peter T. Breuer" <> | Subject | Re: sleep under spinlock, sequencer.c, 2.6.12.5 | Date | Mon, 22 Aug 2005 17:17:44 +0200 (MET DST) |
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"Also sprach Nish Aravamudan:" > On 8/19/05, Alan Cox <alan@lxorguk.ukuu.org.uk> wrote: > > On Gwe, 2005-08-19 at 10:13 +0200, Peter T. Breuer wrote: > > > The following "sleep under spinlock" is still present as of linux > > > 2.6.12.5 in sound/oss/sequencer.c in midi_outc: > > > > > > > > > n = 3 * HZ; /* Timeout */ > > > > > > spin_lock_irqsave(&lock,flags); > > > while (n && !midi_devs[dev]->outputc(dev, data)) { > > > interruptible_sleep_on_timeout(&seq_sleeper, HZ/25); > > > n--; > > > } > > > spin_unlock_irqrestore(&lock,flags); > > > > > > > > > I haven't thought about it, just noted it. It's been there forever > > > (some others in the sound architecture have been gradually disappearing > > > as newer kernels come out). > > > > Yep thats a blind substition of lock_kernel in an old tree it seems. > > Probably my fault. Should drop it before the sleep and take it straight > > after. > > Also, the use of n makes no sense. Indicates total sleep for 3
Well spotted.
> seconds, but actually sleep for 40 milliseconds 3*HZ times > (potentially)?
I presume it should be
n -= HZ/25;
(and "n > 0", of course).
> In any case, probably should be: > > timeout = jiffies + 3*HZ; > > spin_lock_irqsave(&lock, flags); > while (time_before(jiffies, timeout) && !midi_devs[dev]->outputc(dev, data)) { > spin_unlock_irqrestore(&lock, flags); > interruptible_sleep_on_timeout(&seq_sleeper, msecs_to_jiffies(40));
Well, you'd know. Is there something there really not taken care of by "HZ"?
> spin_lock_irqsave(&lock, flags); > } > spin_lock_irqrestore(&lock, flags);
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