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authorOleg Nesterov <oleg@tv-sign.ru>2008-02-08 04:19:00 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2008-02-08 09:22:26 -0800
commitc0c0b649d67aa775aa9851de61aade17504be70c (patch)
tree5902fb53a364155352fcc04e87860d724d8b31fd
parent34a1738f7da0b3d28d4b066d03a78f46b8cab68f (diff)
ptrace_check_attach: remove unneeded ->signal != NULL check
It is not possible to see the PT_PTRACED task without ->signal/sighand under tasklist_lock, release_task() does ptrace_unlink() first. If the task was already released before, ptrace_attach() can't succeed and set PT_PTRACED. Remove this check. Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Acked-by: Roland McGrath <roland@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--kernel/ptrace.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 2dc00298e67..fdb34e86f92 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -99,9 +99,12 @@ int ptrace_check_attach(struct task_struct *child, int kill)
* be changed by us so it's not changing right after this.
*/
read_lock(&tasklist_lock);
- if ((child->ptrace & PT_PTRACED) && child->parent == current &&
- child->signal != NULL) {
+ if ((child->ptrace & PT_PTRACED) && child->parent == current) {
ret = 0;
+ /*
+ * child->sighand can't be NULL, release_task()
+ * does ptrace_unlink() before __exit_signal().
+ */
spin_lock_irq(&child->sighand->siglock);
if (task_is_stopped(child))
child->state = TASK_TRACED;