From: Paul Mundt <lethal@linux-sh.org>
Date: Mon, 8 Sep 2008 09:15:55 +0000 (+0900)
Subject: sh: kprobes: Fix up race against probe point removal.
X-Git-Tag: v2.6.28-rc1~99^2~67
X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=734db3770de03fbe9ae4e78519a7d1678189788c;p=linux-2.6-omap-h63xx.git

sh: kprobes: Fix up race against probe point removal.

Handle a corner case where another CPU or debugger removes the probe
point from underneath us.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
---

diff --git a/arch/sh/kernel/kprobes.c b/arch/sh/kernel/kprobes.c
index f0e1c78d0bf..a478ba78e75 100644
--- a/arch/sh/kernel/kprobes.c
+++ b/arch/sh/kernel/kprobes.c
@@ -252,6 +252,17 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
 	p = get_kprobe(addr);
 	if (!p) {
 		/* Not one of ours: let kernel handle it */
+		if (*(kprobe_opcode_t *)addr != BREAKPOINT_INSTRUCTION) {
+			/*
+			 * The breakpoint instruction was removed right
+			 * after we hit it. Another cpu has removed
+			 * either a probepoint or a debugger breakpoint
+			 * at this address. In either case, no further
+			 * handling of this interrupt is appropriate.
+			 */
+			ret = 1;
+		}
+
 		goto no_kprobe;
 	}