linux-kernel - [PATCH] signals: annotate siglock acquirement

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Date:	Sun, 22 Aug 2010 00:17:38 +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] signals: annotate siglock acquirement

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.

Impact: remove sparse warnings, no runtime overhead.
Signed-off-by: Namhyung Kim <namhyung@...il.com>
---
 kernel/signal.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/kernel/signal.c b/kernel/signal.c
index bded651..c423fc5 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1038,6 +1038,7 @@ int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
 	int ret = -ESRCH;
 
 	if (lock_task_sighand(p, &flags)) {
+		__acquire(&p->sighand->siglock);
 		ret = send_signal(sig, info, p, group);
 		unlock_task_sighand(p, &flags);
 	}
@@ -1227,6 +1228,7 @@ int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid,
 
 	if (sig) {
 		if (lock_task_sighand(p, &flags)) {
+			__acquire(&p->sighand->siglock);
 			ret = __send_signal(sig, info, p, 1, 0);
 			unlock_task_sighand(p, &flags);
 		} else
@@ -1406,6 +1408,8 @@ int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
 	if (!likely(lock_task_sighand(t, &flags)))
 		goto ret;
 
+	__acquire(&t->sighand->siglock);
+
 	ret = 1; /* the signal is ignored */
 	if (!prepare_signal(sig, t, 0))
 		goto out;
-- 
1.7.0.4

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