linux-kernel - [PATCH] signal: annotate siglock acquisition

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Date:	Sat, 25 Sep 2010 18:21:35 +0900
From:	Namhyung Kim <namhyung@...il.com>
To:	Oleg Nesterov <oleg@...hat.com>, Roland McGrath <roland@...hat.com>
Cc:	linux-kernel@...r.kernel.org
Subject: [PATCH] signal: annotate siglock acquisition

lock_task_sighand() conditionally acquires sighand->siglock in case of
returning non-NULL but unlock_task_sighand() releases it unconditionally.
This leads sparse to complain about the lock context imbalance. Annotate it
to make sparse happier.

Signed-off-by: Namhyung Kim <namhyung@...il.com>
---
 kernel/signal.c |    9 ++++++---
 1 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/kernel/signal.c b/kernel/signal.c
index bded651..85c1efd 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1037,7 +1037,7 @@ int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
 	unsigned long flags;
 	int ret = -ESRCH;
 
-	if (lock_task_sighand(p, &flags)) {
+	if (__cond_lock(&p->sighand->siglock, lock_task_sighand(p, &flags))) {
 		ret = send_signal(sig, info, p, group);
 		unlock_task_sighand(p, &flags);
 	}
@@ -1226,7 +1226,8 @@ int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid,
 		goto out_unlock;
 
 	if (sig) {
-		if (lock_task_sighand(p, &flags)) {
+		if (__cond_lock(&p->sighand->siglock,
+				lock_task_sighand(p, &flags))) {
 			ret = __send_signal(sig, info, p, 1, 0);
 			unlock_task_sighand(p, &flags);
 		} else
@@ -1403,7 +1404,9 @@ int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
 	BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
 
 	ret = -1;
-	if (!likely(lock_task_sighand(t, &flags)))
+	if (likely(lock_task_sighand(t, &flags)))
+		__acquire(&t->sighand->siglock);
+	else
 		goto ret;
 
 	ret = 1; /* the signal is ignored */
-- 
1.7.2.2

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