Messages in this thread Patch in this message | | | Date | Tue, 27 Mar 2012 08:34:24 -0700 | From | tip-bot for Peter Zijlstra <> | Subject | [tip:sched/urgent] sched/x86/smp: Do not enable IRQs over calibrate_delay() |
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Commit-ID: bc758133ed73d4b06952bec21da23e28e62bf3ba Gitweb: http://git.kernel.org/tip/bc758133ed73d4b06952bec21da23e28e62bf3ba Author: Peter Zijlstra <a.p.zijlstra@chello.nl> AuthorDate: Mon, 26 Mar 2012 13:16:15 +0200 Committer: Ingo Molnar <mingo@kernel.org> CommitDate: Tue, 27 Mar 2012 14:50:10 +0200
sched/x86/smp: Do not enable IRQs over calibrate_delay()
We should not ever enable IRQs until we're fully set up. This opens up a window where interrupts can hit the cpu and interrupts can do wakeups, wakeups need state that isn't set-up yet, in particular this cpu isn't elegible to run tasks, so if any cpu-affine task that got created in CPU_UP_PREPARE manages to get a wakeup, its affinity mask will get broken and we'll run into lots of 'interesting' problems.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/n/tip-yaezmlbriluh166tfkgni22m@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org> --- arch/x86/kernel/smpboot.c | 5 ----- 1 files changed, 0 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index 58f7816..89571a0 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -219,14 +219,9 @@ static void __cpuinit smp_callin(void) * Update loops_per_jiffy in cpu_data. Previous call to * smp_store_cpu_info() stored a value that is close but not as * accurate as the value just calculated. - * - * Need to enable IRQs because it can take longer and then - * the NMI watchdog might kill us. */ - local_irq_enable(); calibrate_delay(); cpu_data(cpuid).loops_per_jiffy = loops_per_jiffy; - local_irq_disable(); pr_debug("Stack at about %p\n", &cpuid); /*
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