linux-kernel - [PATCH 1/2] x86: fix kprobe

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Message-ID: <4768555A.3000604@redhat.com>
Date:	Tue, 18 Dec 2007 18:18:50 -0500
From:	Masami Hiramatsu <mhiramat@...hat.com>
To:	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Jim Keniston <jkenisto@...ibm.com>, Ingo Molnar <mingo@...e.hu>
CC:	Roland McGrath <roland@...hat.com>, prasanna@...ibm.com,
	anil.s.keshavamurthy@...el.com, davem@...emloft.net,
	Harvey Harrison <harvey.harrison@...il.com>,
	systemtap-ml <systemtap@...rces.redhat.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Arjan van de Ven <arjan@...radead.org>
Subject: [PATCH 1/2] 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 <mhiramat@...hat.com>
---
 arch/x86/kernel/kprobes.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Index: b/arch/x86/kernel/kprobes.c
===================================================================
--- a/arch/x86/kernel/kprobes.c	2007-12-18 12:51:00.000000000 -0500
+++ b/arch/x86/kernel/kprobes.c	2007-12-18 12:53:38.000000000 -0500
@@ -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
@@ -481,7 +482,7 @@
 			kprobes_inc_nmissed_count(p);
 			prepare_singlestep(p, regs);
 			kcb->kprobe_status = KPROBE_REENTER;
-			return 1;
+			ret = 1;
 		} else {
 			if (*addr != BREAKPOINT_INSTRUCTION) {
 			/* The breakpoint instruction was removed by

-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division

e-mail: mhiramat@...hat.com, masami.hiramatsu.pt@...achi.com


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