[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>

1 files changed, 7 insertions, 0 deletions

diff --git a/include/linux/vt_kern.h b/include/linux/vt_kern.h
index 1009d3fe1fc2..37a1a41f5b65 100644
--- a/include/linux/vt_kern.h
+++ b/include/linux/vt_kern.h
@@ -84,4 +84,11 @@ void reset_vc(struct vc_data *vc);
 extern char con_buf[CON_BUF_SIZE];
 extern struct semaphore con_buf_sem;
 
+struct vt_spawn_console {
+        spinlock_t lock;
+        struct pid *pid;
+        int sig;
+};
+extern struct vt_spawn_console vt_spawn_con;
+
 #endif /* _VT_KERN_H */