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signals: move cred_guard_mutex from task_struct to signal_struct

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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>
This commit is contained in:
KOSAKI Motohiro
2010-10-27 15:34:08 -07:00
committed by Linus Torvalds
parent b840115083
commit 9b1bf12d5d
8 changed files with 21 additions and 20 deletions
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8
fs/proc/base.c
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@@ -226,7 +226,7 @@ struct mm_struct *mm_for_maps(struct task_struct *task)
{
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 @@ struct mm_struct *mm_for_maps(struct task_struct *task)
mmput(mm);
mm = NULL;
}
mutex_unlock(&task->cred_guard_mutex);
mutex_unlock(&task->signal->cred_guard_mutex);
return mm;
}
@@ -2354,14 +2354,14 @@ static ssize_t proc_pid_attr_write(struct file * file, const char __user * buf,
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: