]> pilppa.com Git - linux-2.6-omap-h63xx.git/commit
xtime_lock vs update_process_times
authorPeter Zijlstra <a.p.zijlstra@chello.nl>
Wed, 13 Feb 2008 20:33:16 +0000 (21:33 +0100)
committerLinus Torvalds <torvalds@woody.linux-foundation.org>
Wed, 13 Feb 2008 21:29:25 +0000 (13:29 -0800)
commitaa02cd2d9bd1e24a230bd66a0a741b984d03915a
tree06e341e095749048feabbe2ded236e5db38ee251
parent10270d4838bdc493781f5a1cf2e90e9c34c9142f
xtime_lock vs update_process_times

Commit d3d74453c34f8fd87674a8cf5b8a327c68f22e99 ("hrtimer: fixup the
HRTIMER_CB_IRQSAFE_NO_SOFTIRQ fallback") broke several archs, and since
only Russell bothered to merge the fix, and Greg to ACK his arch, I'm
sending this for merger.

I have confirmation that the Alpha bit results in a booting kernel.
That leaves: blackfin, frv, sh and sparc untested.

The deadlock in question was found by Russell:

  IRQ handle
    -> timer_tick() - xtime seqlock held for write
      -> update_process_times()
        -> run_local_timers()
          -> hrtimer_run_queues()
            -> hrtimer_get_softirq_time() - tries to get a read lock

Now, Thomas assures me the fix is trivial, only do_timer() needs to be
done under the xtime_lock, and update_process_times() can savely be
removed from under it.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Greg Ungerer <gerg@uclinux.org>
CC: Richard Henderson <rth@twiddle.net>
CC: Bryan Wu <bryan.wu@analog.com>
CC: David Howells <dhowells@redhat.com>
CC: Paul Mundt <lethal@linux-sh.org>
CC: William Irwin <wli@holomorphy.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
arch/alpha/kernel/time.c
arch/blackfin/kernel/time.c
arch/frv/kernel/time.c
arch/m68knommu/kernel/time.c
arch/sh/kernel/timers/timer-cmt.c
arch/sh/kernel/timers/timer-mtu2.c
arch/sparc/kernel/pcic.c
arch/sparc/kernel/time.c