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| author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2008-02-13 21:33:16 +0100 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2008-02-13 13:29:25 -0800 |
| commit | aa02cd2d9bd1e24a230bd66a0a741b984d03915a (patch) | |
| tree | 06e341e095749048feabbe2ded236e5db38ee251 /arch/m68knommu | |
| parent | 10270d4838bdc493781f5a1cf2e90e9c34c9142f (diff) | |
| download | linux-aa02cd2d9bd1e24a230bd66a0a741b984d03915a.tar.gz linux-aa02cd2d9bd1e24a230bd66a0a741b984d03915a.tar.bz2 linux-aa02cd2d9bd1e24a230bd66a0a741b984d03915a.zip | |
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>
Diffstat (limited to 'arch/m68knommu')
| -rw-r--r-- | arch/m68knommu/kernel/time.c | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/arch/m68knommu/kernel/time.c b/arch/m68knommu/kernel/time.c index 89cdbcaeb45f..0ccfb2ad6380 100644 --- a/arch/m68knommu/kernel/time.c +++ b/arch/m68knommu/kernel/time.c @@ -42,14 +42,12 @@ irqreturn_t arch_timer_interrupt(int irq, void *dummy) /* last time the cmos clock got updated */ static long last_rtc_update=0; + if (current->pid) + profile_tick(CPU_PROFILING); + write_seqlock(&xtime_lock); do_timer(1); -#ifndef CONFIG_SMP - update_process_times(user_mode(get_irq_regs())); -#endif - if (current->pid) - profile_tick(CPU_PROFILING); /* * If we have an externally synchronized Linux clock, then update @@ -67,6 +65,10 @@ irqreturn_t arch_timer_interrupt(int irq, void *dummy) } write_sequnlock(&xtime_lock); + +#ifndef CONFIG_SMP + update_process_times(user_mode(get_irq_regs())); +#endif return(IRQ_HANDLED); } |