signals: move cred_guard_mutex from task_struct to signal_struct
Oleg Nesterov pointed out we have to prevent multiple-threads-inside-exec
itself and we can reuse ->cred_guard_mutex for it. Yes, concurrent
execve() has no worth.
Let's move ->cred_guard_mutex from task_struct to signal_struct. It
naturally prevent multiple-threads-inside-exec.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Roland McGrath <roland@redhat.com>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 9b094c1..f3d02ca 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -226,7 +226,7 @@
{
struct mm_struct *mm;
- if (mutex_lock_killable(&task->cred_guard_mutex))
+ if (mutex_lock_killable(&task->signal->cred_guard_mutex))
return NULL;
mm = get_task_mm(task);
@@ -235,7 +235,7 @@
mmput(mm);
mm = NULL;
}
- mutex_unlock(&task->cred_guard_mutex);
+ mutex_unlock(&task->signal->cred_guard_mutex);
return mm;
}
@@ -2354,14 +2354,14 @@
goto out_free;
/* Guard against adverse ptrace interaction */
- length = mutex_lock_interruptible(&task->cred_guard_mutex);
+ length = mutex_lock_interruptible(&task->signal->cred_guard_mutex);
if (length < 0)
goto out_free;
length = security_setprocattr(task,
(char*)file->f_path.dentry->d_name.name,
(void*)page, count);
- mutex_unlock(&task->cred_guard_mutex);
+ mutex_unlock(&task->signal->cred_guard_mutex);
out_free:
free_page((unsigned long) page);
out: