From: Oleg Nesterov <oleg@redhat.com>
Date: Wed, 17 Jun 2009 23:27:36 +0000 (-0700)
Subject: ptrace: don't take tasklist to get/set ->last_siginfo
X-Git-Tag: v2.6.31-rc1~214
X-Git-Url: http://ftp.safe.ca/?p=safe%2Fjmp%2Flinux-2.6;a=commitdiff_plain;h=e49612544c695117644af48bb4625264a3d2918f

ptrace: don't take tasklist to get/set ->last_siginfo

Change ptrace_getsiginfo/ptrace_setsiginfo to use lock_task_sighand()
without tasklist_lock.  Perhaps it makes sense to make a single helper
with "bool rw" argument.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index a64fe75..61c78b2 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -424,37 +424,33 @@ static int ptrace_setoptions(struct task_struct *child, long data)
 
 static int ptrace_getsiginfo(struct task_struct *child, siginfo_t *info)
 {
+	unsigned long flags;
 	int error = -ESRCH;
 
-	read_lock(&tasklist_lock);
-	if (likely(child->sighand != NULL)) {
+	if (lock_task_sighand(child, &flags)) {
 		error = -EINVAL;
-		spin_lock_irq(&child->sighand->siglock);
 		if (likely(child->last_siginfo != NULL)) {
 			*info = *child->last_siginfo;
 			error = 0;
 		}
-		spin_unlock_irq(&child->sighand->siglock);
+		unlock_task_sighand(child, &flags);
 	}
-	read_unlock(&tasklist_lock);
 	return error;
 }
 
 static int ptrace_setsiginfo(struct task_struct *child, const siginfo_t *info)
 {
+	unsigned long flags;
 	int error = -ESRCH;
 
-	read_lock(&tasklist_lock);
-	if (likely(child->sighand != NULL)) {
+	if (lock_task_sighand(child, &flags)) {
 		error = -EINVAL;
-		spin_lock_irq(&child->sighand->siglock);
 		if (likely(child->last_siginfo != NULL)) {
 			*child->last_siginfo = *info;
 			error = 0;
 		}
-		spin_unlock_irq(&child->sighand->siglock);
+		unlock_task_sighand(child, &flags);
 	}
-	read_unlock(&tasklist_lock);
 	return error;
 }