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redo locking of tty->pgrp

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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>
This commit is contained in:
Alan Cox
2008-04-30 00:53:30 -07:00
committed by Linus Torvalds
parent 04f378b198
commit 47f86834bb
3 changed files with 72 additions and 22 deletions
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10
include/linux/tty.h
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@@ -184,21 +184,22 @@ struct tty_struct {
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 @@ struct tty_struct {
/*
* 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;