redo locking of tty->pgrp
Historically tty->pgrp and friends were pid_t and the code "knew" they were
safe. The change to pid structs opened up a few races and the removal of the
BKL in places made them quite hittable. We put tty->pgrp under the ctrl_lock
for the tty.
Signed-off-by: Alan Cox <alan@redhat.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 4d3702ba..381085e 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -184,21 +184,22 @@
struct tty_ldisc ldisc;
struct mutex termios_mutex;
spinlock_t ctrl_lock;
+ /* Termios values are protected by the termios mutex */
struct ktermios *termios, *termios_locked;
char name[64];
- struct pid *pgrp;
+ struct pid *pgrp; /* Protected by ctrl lock */
struct pid *session;
unsigned long flags;
int count;
- struct winsize winsize;
+ struct winsize winsize; /* termios mutex */
unsigned char stopped:1, hw_stopped:1, flow_stopped:1, packet:1;
unsigned char low_latency:1, warned:1;
- unsigned char ctrl_status;
+ unsigned char ctrl_status; /* ctrl_lock */
unsigned int receive_room; /* Bytes free for queue */
struct tty_struct *link;
struct fasync_struct *fasync;
- struct tty_bufhead buf;
+ struct tty_bufhead buf; /* Locked internally */
int alt_speed; /* For magic substitution of 38400 bps */
wait_queue_head_t write_wait;
wait_queue_head_t read_wait;
@@ -212,6 +213,7 @@
/*
* The following is data for the N_TTY line discipline. For
* historical reasons, this is included in the tty structure.
+ * Mostly locked by the BKL.
*/
unsigned int column;
unsigned char lnext:1, erasing:1, raw:1, real_raw:1, icanon:1;