Pull xpc-disengage into release branch

[karo-tx-linux.git] / kernel / kprobes.c

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 3b7653f2e7aec10ce0ef94b038c551607cb9d440..f3ea492ab44dfcfc05e2fad4027e303f9b69d9dd 100644 (file)
--- 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 */