diff options
| author | Linus Torvalds | 2009-08-03 10:58:29 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman | 2009-08-04 13:46:30 -0700 |
| commit | 18eac1cc100fa2afd5f39085aae6b694e417734b (patch) | |
| tree | 52ac69ef9832c77a0c6865f9eff39dd4f287776e | |
| parent | a33a052f19a21d727847391c8c1aff3fb221c472 (diff) | |
tty-ldisc: make refcount be atomic_t 'users' count
This is pure preparation of changing the ldisc reference counting to be
a true refcount that defines the lifetime of the ldisc. But this is a
purely syntactic change for now to make the next steps easier.
This patch should make no semantic changes at all. But I wanted to make
the ldisc refcount be an atomic (I will be touching it without locks
soon enough), and I wanted to rename it so that there isn't quite as
much confusion between 'ldo->refcount' (ldisk operations refcount) and
'ld->refcount' (ldisc refcount itself) in the same file.
So it's now an atomic 'ld->users' count. It still starts at zero,
despite having a reference from 'tty->ldisc', but that will change once
we turn it into a _real_ refcount.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Tested-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Tested-by: Sergey Senozhatsky <sergey.senozhatsky@mail.by>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | drivers/char/tty_ldisc.c | 18 | ||||
| -rw-r--r-- | include/linux/tty_ldisc.h | 2 |
2 files changed, 9 insertions, 11 deletions
diff --git a/drivers/char/tty_ldisc.c b/drivers/char/tty_ldisc.c index acd76b767d4c..fd175e60aad5 100644 --- a/drivers/char/tty_ldisc.c +++ b/drivers/char/tty_ldisc.c @@ -142,7 +142,7 @@ static struct tty_ldisc *tty_ldisc_try_get(int disc) /* lock it */ ldops->refcount++; ld->ops = ldops; - ld->refcount = 0; + atomic_set(&ld->users, 0); err = 0; } } @@ -206,7 +206,7 @@ static void tty_ldisc_put(struct tty_ldisc *ld) ldo->refcount--; module_put(ldo->owner); spin_unlock_irqrestore(&tty_ldisc_lock, flags); - WARN_ON(ld->refcount); + WARN_ON(atomic_read(&ld->users)); kfree(ld); } @@ -297,7 +297,7 @@ static int tty_ldisc_try(struct tty_struct *tty) spin_lock_irqsave(&tty_ldisc_lock, flags); ld = tty->ldisc; if (test_bit(TTY_LDISC, &tty->flags)) { - ld->refcount++; + atomic_inc(&ld->users); ret = 1; } spin_unlock_irqrestore(&tty_ldisc_lock, flags); @@ -324,7 +324,7 @@ struct tty_ldisc *tty_ldisc_ref_wait(struct tty_struct *tty) { /* wait_event is a macro */ wait_event(tty_ldisc_wait, tty_ldisc_try(tty)); - WARN_ON(tty->ldisc->refcount == 0); + WARN_ON(atomic_read(&tty->ldisc->users) == 0); return tty->ldisc; } EXPORT_SYMBOL_GPL(tty_ldisc_ref_wait); @@ -365,11 +365,9 @@ void tty_ldisc_deref(struct tty_ldisc *ld) BUG_ON(ld == NULL); spin_lock_irqsave(&tty_ldisc_lock, flags); - if (ld->refcount == 0) + if (atomic_read(&ld->users) == 0) printk(KERN_ERR "tty_ldisc_deref: no references.\n"); - else - ld->refcount--; - if (ld->refcount == 0) + else if (atomic_dec_and_test(&ld->users)) wake_up(&tty_ldisc_wait); spin_unlock_irqrestore(&tty_ldisc_lock, flags); } @@ -536,10 +534,10 @@ static int tty_ldisc_wait_idle(struct tty_struct *tty) { unsigned long flags; spin_lock_irqsave(&tty_ldisc_lock, flags); - while (tty->ldisc->refcount) { + while (atomic_read(&tty->ldisc->users)) { spin_unlock_irqrestore(&tty_ldisc_lock, flags); if (wait_event_timeout(tty_ldisc_wait, - tty->ldisc->refcount == 0, 5 * HZ) == 0) + atomic_read(&tty->ldisc->users) == 0, 5 * HZ) == 0) return -EBUSY; spin_lock_irqsave(&tty_ldisc_lock, flags); } diff --git a/include/linux/tty_ldisc.h b/include/linux/tty_ldisc.h index 40f38d896777..0c4ee9b88f85 100644 --- a/include/linux/tty_ldisc.h +++ b/include/linux/tty_ldisc.h @@ -144,7 +144,7 @@ struct tty_ldisc_ops { struct tty_ldisc { struct tty_ldisc_ops *ops; - int refcount; + atomic_t users; }; #define TTY_LDISC_MAGIC 0x5403 |