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authorOleg Nesterov <oleg@redhat.com>2012-03-05 14:59:13 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2012-03-05 15:49:42 -0800
commitd68b46fe16ad59b3a5f51ec73daaa5dc06753798 (patch)
tree4bae9ddc5f5bed853d1f0936d05c30e4f7ca924d /include
parentc415c3b47ea2754659d915cca387a20999044163 (diff)
vfork: make it killable
Make vfork() killable. Change do_fork(CLONE_VFORK) to do wait_for_completion_killable(). If it fails we do not return to the user-mode and never touch the memory shared with our child. However, in this case we should clear child->vfork_done before return, we use task_lock() in do_fork()->wait_for_vfork_done() and complete_vfork_done() to serialize with each other. Note: now that we use task_lock() we don't really need completion, we could turn task->vfork_done into "task_struct *wake_up_me" but this needs some complications. NOTE: this and the next patches do not affect in-kernel users of CLONE_VFORK, kernel threads run with all signals ignored including SIGKILL/SIGSTOP. However this is obviously the user-visible change. Not only a fatal signal can kill the vforking parent, a sub-thread can do execve or exit_group() and kill the thread sleeping in vfork(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/sched.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 1b25a37f2ae..b6467711f12 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2372,7 +2372,7 @@ static inline int thread_group_empty(struct task_struct *p)
* Protects ->fs, ->files, ->mm, ->group_info, ->comm, keyring
* subscriptions and synchronises with wait4(). Also used in procfs. Also
* pins the final release of task.io_context. Also protects ->cpuset and
- * ->cgroup.subsys[].
+ * ->cgroup.subsys[]. And ->vfork_done.
*
* Nests both inside and outside of read_lock(&tasklist_lock).
* It must not be nested with write_lock_irq(&tasklist_lock),