x86: fix kprobe_handler reenable preemption

Fix a preemption bug in kprobe_handler(). It has to call preempt_enable() before returning.
I think this is critical on preemptive kernel.

Signed-off-by Masami Hiramatsu <[email protected]>

---
 arch/x86/kernel/kprobes.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Index: b/arch/x86/kernel/kprobes.c
===================================================================

arch/x86/kernel/kprobes.c +2 -1

@@ -467,7 +467,8 @@
 				arch_disarm_kprobe(p);
 				regs->ip = (unsigned long)p->addr;
 				reset_current_kprobe();
-				return 1;
+				ret = 1;
+				goto no_kprobe;
 #endif
 			}
 			/* We have reentered the kprobe_handler(), since

arch/x86/kernel/kprobes.c +0 -0

 		} else {
 			if (*addr != BREAKPOINT_INSTRUCTION) {
 			/* The breakpoint instruction was removed by

Review

Quoted 2 lines

(quoted diff) +1 -1

-			return 1;
+			ret = 1;

Here, "return 1;" is correct. After single step is done, preemption is enabled in post_kprobe_handler().

Quoted 4 lines · Masami Hiramatsu

Review

Quoted 2 lines

(quoted diff) +1 -1

-			return 1;
+			ret = 1;

Here, "return 1;" is correct. After single step is done, preemption is enabled in post_kprobe_handler().

could you resend the fixed patch? (instead of me fixing it up by hand - which is error-prone)

also, this seems like .24 material as well - could you send the fix against -rc5 too?

Ingo