[PATCH RESEND] signal: annotate siglock acquisition

[PATCH RESEND] signal: annotate siglock acquisition

[Namhyung Kim]

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@gmail.com>
---
 kernel/signal.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/kernel/signal.c b/kernel/signal.c
index bded651..766ae03 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);  /* make sparse happy */
 		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); /* make sparse happy */
+
 	ret = 1; /* the signal is ignored */
 	if (!prepare_signal(sig, t, 0))
 		goto out;
-- 
1.7.2.2

Re: [PATCH RESEND] signal: annotate siglock acquisition

[Al Viro]

On Sat, Sep 25, 2010 at 12:20:56PM +0900, Namhyung Kim wrote:
> 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.

That's not a good way to do it; use __cond_lock instead.

Re: [PATCH RESEND] signal: annotate siglock acquisition

[Namhyung Kim]

On Sat, Sep 25, 2010 at 12:26, Al Viro <viro@zeniv.linux.org.uk> wrote:
> On Sat, Sep 25, 2010 at 12:20:56PM +0900, Namhyung Kim wrote:
>> 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.
>
> That's not a good way to do it; use __cond_lock instead.
>

Thanks. I'll resend a patch that uses it.


-- 
Regards,
Namhyung Kim