From deac66ae454cacf942c051b86d9232af546fb187 Mon Sep 17 00:00:00 2001 From: Keshavamurthy Anil S Date: Tue, 6 Sep 2005 15:19:35 -0700 Subject: [PATCH] kprobes: fix bug when probed on task and isr functions This patch fixes a race condition where in system used to hang or sometime crash within minutes when kprobes are inserted on ISR routine and a task routine. The fix has been stress tested on i386, ia64, pp64 and on x86_64. To reproduce the problem insert kprobes on schedule() and do_IRQ() functions and you should see hang or system crash. Signed-off-by: Anil S Keshavamurthy Signed-off-by: Ananth N Mavinakayanahalli Acked-by: Prasanna S Panchamukhi Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/kprobes.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) (limited to 'kernel/kprobes.c') diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 3b7653f2e7a..f3ea492ab44 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -155,14 +155,36 @@ void __kprobes free_insn_slot(kprobe_opcode_t *slot) /* Locks kprobe: irqs must be disabled */ 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); } 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); } /* You have to be holding the kprobe_lock */ -- cgit v1.2.3-70-g09d2