linux-kernel - [tip:tracing/urgent] kprobes: No need to unlock kprobe_insn

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Message-ID: <tip-4ca2efad573aef3cad6157bb7c0036435f87a329@git.kernel.org>
Date:	Tue, 30 Jun 2009 21:40:06 GMT
From:	tip-bot for Masami Hiramatsu <mhiramat@...hat.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, ananth@...ibm.com, hpa@...or.com,
	mingo@...hat.com, jkenisto@...ibm.com, tglx@...utronix.de,
	mhiramat@...hat.com, mingo@...e.hu
Subject: [tip:tracing/urgent] kprobes: No need to unlock kprobe_insn_mutex

Commit-ID:  4ca2efad573aef3cad6157bb7c0036435f87a329
Gitweb:     http://git.kernel.org/tip/4ca2efad573aef3cad6157bb7c0036435f87a329
Author:     Masami Hiramatsu <mhiramat@...hat.com>
AuthorDate: Tue, 30 Jun 2009 17:08:09 -0400
Committer:  Ingo Molnar <mingo@...e.hu>
CommitDate: Tue, 30 Jun 2009 23:21:58 +0200

kprobes: No need to unlock kprobe_insn_mutex

Remove needless kprobe_insn_mutex unlocking during safety check
in garbage collection, because if someone releases a dirty slot
during safety check (which ensures other cpus doesn't execute
all dirty slots), the safety check must be fail. So, we need to
hold the mutex while checking safety.

Signed-off-by: Masami Hiramatsu <mhiramat@...hat.com>
Cc: Ananth N Mavinakayanahalli <ananth@...ibm.com>
Cc: Jim Keniston <jkenisto@...ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@...ibm.com>
LKML-Reference: <20090630210809.17851.28781.stgit@...alhost.localdomain>
Signed-off-by: Ingo Molnar <mingo@...e.hu>


---
 kernel/kprobes.c |    6 +-----
 1 files changed, 1 insertions(+), 5 deletions(-)

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index c0fa54b..16b5739 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -237,13 +237,9 @@ static int __kprobes collect_garbage_slots(void)
 {
 	struct kprobe_insn_page *kip;
 	struct hlist_node *pos, *next;
-	int safety;
 
 	/* Ensure no-one is preepmted on the garbages */
-	mutex_unlock(&kprobe_insn_mutex);
-	safety = check_safety();
-	mutex_lock(&kprobe_insn_mutex);
-	if (safety != 0)
+	if (check_safety())
 		return -EAGAIN;
 
 	hlist_for_each_entry_safe(kip, pos, next, &kprobe_insn_pages, hlist) {
--
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