Commit c0c0b649 authored Feb 08, 2008 by Oleg Nesterov Committed by Linus Torvalds Feb 08, 2008

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>

parent 34a1738f

kernel/ptrace.c

+5 −2

Original line number	Diff line number	Diff line
		@@ -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;