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[PATCH] kprobes: fix bug when probed on task and isr functions

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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 <anil.s.keshavamurthy@intel.com>
Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Acked-by: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Keshavamurthy Anil S
2005-09-06 15:19:35 -07:00
committed by Linus Torvalds
parent bce0649417
commit deac66ae45
7 changed files with 55 additions and 10 deletions
Download Patch File Download Diff File Expand all files Collapse all files

22
kernel/kprobes.c
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@ -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 */