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author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2008-02-13 21:33:16 +0100 |
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committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2008-02-13 13:29:25 -0800 |
commit | aa02cd2d9bd1e24a230bd66a0a741b984d03915a (patch) | |
tree | 06e341e095749048feabbe2ded236e5db38ee251 /arch/sh | |
parent | 10270d4838bdc493781f5a1cf2e90e9c34c9142f (diff) | |
download | linux-aa02cd2d9bd1e24a230bd66a0a741b984d03915a.tar.gz |
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/sh')
-rw-r--r-- | arch/sh/kernel/timers/timer-cmt.c | 9 | ||||
-rw-r--r-- | arch/sh/kernel/timers/timer-mtu2.c | 2 |
2 files changed, 0 insertions, 11 deletions
diff --git a/arch/sh/kernel/timers/timer-cmt.c b/arch/sh/kernel/timers/timer-cmt.c index 499e07beebe2..71312324b5de 100644 --- a/arch/sh/kernel/timers/timer-cmt.c +++ b/arch/sh/kernel/timers/timer-cmt.c @@ -100,16 +100,7 @@ static irqreturn_t cmt_timer_interrupt(int irq, void *dev_id) timer_status &= ~0x80; ctrl_outw(timer_status, CMT_CMCSR_0); - /* - * Here we are in the timer irq handler. We just have irqs locally - * disabled but we don't know if the timer_bh is running on the other - * CPU. We need to avoid to SMP race with it. NOTE: we don' t need - * the irq version of write_lock because as just said we have irq - * locally disabled. -arca - */ - write_seqlock(&xtime_lock); handle_timer_tick(); - write_sequnlock(&xtime_lock); return IRQ_HANDLED; } diff --git a/arch/sh/kernel/timers/timer-mtu2.c b/arch/sh/kernel/timers/timer-mtu2.c index b7499a2a9188..463cd08f9517 100644 --- a/arch/sh/kernel/timers/timer-mtu2.c +++ b/arch/sh/kernel/timers/timer-mtu2.c @@ -100,9 +100,7 @@ static irqreturn_t mtu2_timer_interrupt(int irq, void *dev_id) ctrl_outb(timer_status, MTU2_TSR_1); /* Do timer tick */ - write_seqlock(&xtime_lock); handle_timer_tick(); - write_sequnlock(&xtime_lock); return IRQ_HANDLED; } |