Messages in this thread Patch in this message | | | Date | Thu, 1 Sep 2005 16:12:18 -0700 | From | Keshavamurthy Anil S <> | Subject | [PATCH]kprobes comment patch around kprobes lock functions |
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On Thu, Sep 01, 2005 at 02:09:38PM -0700, Andrew Morton wrote: > Now, probably there's deep magic happening here and I'm wrong. If so then > please explain the code's magic via a comment patch so the question doesn't > arise again, thanks. >
This is a comment patch around lock_kprobes() and unlock_kprobes() functions.
Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
=================================================================== kernel/kprobes.c | 14 ++++++++++++++ 1 files changed, 14 insertions(+)
Index: linux-2.6.13-mm1/kernel/kprobes.c =================================================================== --- linux-2.6.13-mm1.orig/kernel/kprobes.c +++ linux-2.6.13-mm1/kernel/kprobes.c @@ -157,9 +157,16 @@ void __kprobes lock_kprobes(void) { unsigned long flags = 0; + /* Avoiding local interrupts to happen right after we take the kprobe_lock + * and before we get a chance to update kprobe_cpu, this to prevent + * deadlock when we have a kprobe on ISR routine and a kprobe on task + * routine + */ local_irq_save(flags); + spin_lock(&kprobe_lock); kprobe_cpu = smp_processor_id(); + local_irq_restore(flags); } @@ -167,9 +174,16 @@ void __kprobes unlock_kprobes(void) { unsigned long flags = 0; + /* Avoiding local interrupts to happen right after we update + * kprobe_cpu and before we get a a chance to release kprobe_lock, + * this to prevent deadlock when we have a kprobe on ISR routine and + * a kprobe on task routine + */ local_irq_save(flags); + kprobe_cpu = NR_CPUS; spin_unlock(&kprobe_lock); + local_irq_restore(flags); } - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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