[PATCH] vt: rework the console spawning variables
This is such a rare path it took me a while to figure out how to test
this after soring out the locking.
This patch does several things.
- The variables used are moved into a structure and declared in vt_kern.h
- A spinlock is added so we don't have SMP races updating the values.
- Instead of raw pid_t value a struct_pid is used to guard against
pid wrap around issues, if the daemon to spawn a new console dies.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/drivers/char/vt_ioctl.c b/drivers/char/vt_ioctl.c
index a53e382..dc408af 100644
--- a/drivers/char/vt_ioctl.c
+++ b/drivers/char/vt_ioctl.c
@@ -645,13 +645,16 @@
*/
case KDSIGACCEPT:
{
- extern int spawnpid, spawnsig;
if (!perm || !capable(CAP_KILL))
return -EPERM;
if (!valid_signal(arg) || arg < 1 || arg == SIGKILL)
return -EINVAL;
- spawnpid = current->pid;
- spawnsig = arg;
+
+ spin_lock_irq(&vt_spawn_con.lock);
+ put_pid(vt_spawn_con.pid);
+ vt_spawn_con.pid = get_pid(task_pid(current));
+ vt_spawn_con.sig = arg;
+ spin_unlock_irq(&vt_spawn_con.lock);
return 0;
}