On 01/01/15 02:16, Hans Petter Selasky wrote:
On 01/01/15 02:02, Hans Petter Selasky wrote:
On 12/31/14 23:56, Ivan Klymenko wrote:
В Mon, 29 Dec 2014 21:03:24 +0100
Hans Petter Selasky <h...@selasky.org> пишет:
Hi,
Is your kernel compiled with Witness? Do you see any lock order reversal
warnings?
Can you do from kgdb:
thread apply all bt
And send me the result off-list?
I'll have a closer look at this tomorrow.
panic: spin lock held too long
http://paste.org.ru/?acf7io
Thank you!
Hi,
I see what is going on. There is an LOR which is not printed because
MTX_QUIET is passed when locking inside the callback process routine.
It happens because cv_timedwait() is using callouts() to timeout and
callout_drain() is using cv_wait() to wait for draining. This was not so
well documented in the old code.
I'll update my patch and send out a new one later today.
I see a room for doing some improvements too:
callout_init(&td->td_slpcallout, CALLOUT_MPSAFE)
Possibly we could use a so-called "DIRECT" callback from the fast IRQ of
the timer, when waking up other threads from cv_timedwait(), hence only
spinlocks are involved? This would save waking up the callout SWI only
to wakeup another thread !
Thank you for testing!
--HPS
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