Messages in this thread | | | Date | Fri, 8 Aug 2008 12:14:28 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] printk: robustify printk |
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On Fri, 08 Aug 2008 20:14:28 +0200 Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:
> void wake_up_klogd(void) > { > - if (!oops_in_progress && waitqueue_active(&log_wait)) > - wake_up_interruptible(&log_wait); > + unsigned long flags; > + struct klogd_wakeup_state *kws; > + > + if (!waitqueue_active(&log_wait)) > + return; > + > + local_irq_save(flags); > + kws = &__get_cpu_var(kws); > + if (!kws->pending) { > + kws->pending = 1; > + call_rcu(&kws->head, __wake_up_klogd); > + } > + local_irq_restore(flags); > }
Note that kernel/rcupreempt.c's flavour of call_rcu() takes RCU_DATA_ME().lock, so there are still code sites from which a printk can deadlock. Only now, it is config-dependent.
From a quick look it appears that large amounts of kernel/rcupreempt.c are now a printk-free zone.
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