diff options
Diffstat (limited to 'drivers/char/tty_io.c')
| -rw-r--r-- | drivers/char/tty_io.c | 87 |
1 files changed, 59 insertions, 28 deletions
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c index 9d657127f31..e5953f3433f 100644 --- a/drivers/char/tty_io.c +++ b/drivers/char/tty_io.c @@ -469,21 +469,19 @@ static void tty_ldisc_enable(struct tty_struct *tty) static int tty_set_ldisc(struct tty_struct *tty, int ldisc) { - int retval = 0; - struct tty_ldisc o_ldisc; + int retval = 0; + struct tty_ldisc o_ldisc; char buf[64]; int work; unsigned long flags; struct tty_ldisc *ld; + struct tty_struct *o_tty; if ((ldisc < N_TTY) || (ldisc >= NR_LDISCS)) return -EINVAL; restart: - if (tty->ldisc.num == ldisc) - return 0; /* We are already in the desired discipline */ - ld = tty_ldisc_get(ldisc); /* Eduardo Blanco <ejbs@cs.cs.com.uy> */ /* Cyrus Durgin <cider@speakeasy.org> */ @@ -494,45 +492,74 @@ restart: if (ld == NULL) return -EINVAL; - o_ldisc = tty->ldisc; - tty_wait_until_sent(tty, 0); + if (tty->ldisc.num == ldisc) { + tty_ldisc_put(ldisc); + return 0; + } + + o_ldisc = tty->ldisc; + o_tty = tty->link; + /* * Make sure we don't change while someone holds a * reference to the line discipline. The TTY_LDISC bit * prevents anyone taking a reference once it is clear. * We need the lock to avoid racing reference takers. */ - + spin_lock_irqsave(&tty_ldisc_lock, flags); - if(tty->ldisc.refcount) - { - /* Free the new ldisc we grabbed. Must drop the lock - first. */ + if (tty->ldisc.refcount || (o_tty && o_tty->ldisc.refcount)) { + if(tty->ldisc.refcount) { + /* Free the new ldisc we grabbed. Must drop the lock + first. */ + spin_unlock_irqrestore(&tty_ldisc_lock, flags); + tty_ldisc_put(ldisc); + /* + * There are several reasons we may be busy, including + * random momentary I/O traffic. We must therefore + * retry. We could distinguish between blocking ops + * and retries if we made tty_ldisc_wait() smarter. That + * is up for discussion. + */ + if (wait_event_interruptible(tty_ldisc_wait, tty->ldisc.refcount == 0) < 0) + return -ERESTARTSYS; + goto restart; + } + if(o_tty && o_tty->ldisc.refcount) { + spin_unlock_irqrestore(&tty_ldisc_lock, flags); + tty_ldisc_put(ldisc); + if (wait_event_interruptible(tty_ldisc_wait, o_tty->ldisc.refcount == 0) < 0) + return -ERESTARTSYS; + goto restart; + } + } + + /* if the TTY_LDISC bit is set, then we are racing against another ldisc change */ + + if (!test_bit(TTY_LDISC, &tty->flags)) { spin_unlock_irqrestore(&tty_ldisc_lock, flags); tty_ldisc_put(ldisc); - /* - * There are several reasons we may be busy, including - * random momentary I/O traffic. We must therefore - * retry. We could distinguish between blocking ops - * and retries if we made tty_ldisc_wait() smarter. That - * is up for discussion. - */ - if(wait_event_interruptible(tty_ldisc_wait, tty->ldisc.refcount == 0) < 0) - return -ERESTARTSYS; + ld = tty_ldisc_ref_wait(tty); + tty_ldisc_deref(ld); goto restart; } - clear_bit(TTY_LDISC, &tty->flags); + + clear_bit(TTY_LDISC, &tty->flags); clear_bit(TTY_DONT_FLIP, &tty->flags); + if (o_tty) { + clear_bit(TTY_LDISC, &o_tty->flags); + clear_bit(TTY_DONT_FLIP, &o_tty->flags); + } spin_unlock_irqrestore(&tty_ldisc_lock, flags); - + /* * From this point on we know nobody has an ldisc * usage reference, nor can they obtain one until * we say so later on. */ - + work = cancel_delayed_work(&tty->flip.work); /* * Wait for ->hangup_work and ->flip.work handlers to terminate @@ -583,10 +610,12 @@ restart: */ tty_ldisc_enable(tty); + if (o_tty) + tty_ldisc_enable(o_tty); /* Restart it in case no characters kick it off. Safe if already running */ - if(work) + if (work) schedule_delayed_work(&tty->flip.work, 1); return retval; } @@ -2425,6 +2454,7 @@ static void __do_SAK(void *arg) int i; struct file *filp; struct tty_ldisc *disc; + struct fdtable *fdt; if (!tty) return; @@ -2450,8 +2480,9 @@ static void __do_SAK(void *arg) } task_lock(p); if (p->files) { - spin_lock(&p->files->file_lock); - for (i=0; i < p->files->max_fds; i++) { + rcu_read_lock(); + fdt = files_fdtable(p->files); + for (i=0; i < fdt->max_fds; i++) { filp = fcheck_files(p->files, i); if (!filp) continue; @@ -2464,7 +2495,7 @@ static void __do_SAK(void *arg) break; } } - spin_unlock(&p->files->file_lock); + rcu_read_unlock(); } task_unlock(p); } while_each_task_pid(session, PIDTYPE_SID, p); |