Gitweb:     http://git.kernel.org/linus/e49612544c695117644af48bb4625264a3d2918f
Commit:     e49612544c695117644af48bb4625264a3d2918f
Parent:     d92656633b8352c6d4b14afcb7beb154d76e7aa6
Author:     Oleg Nesterov <oleg@redhat.com>
AuthorDate: Wed Jun 17 16:27:36 2009 -0700
Committer:  Linus Torvalds <torvalds@linux-foundation.org>
CommitDate: Thu Jun 18 13:03:52 2009 -0700

    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>
---
 kernel/ptrace.c |   16 ++++++----------
 1 files changed, 6 insertions(+), 10 deletions(-)

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;
 }
 
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