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TTY: ircomm, revamp locking 

Use self->spinlock only for ctrl_skb and tx_skb. TTY stuff is now
protected by tty_port->lock. This is needed for further cleanup (and
conversion to tty_port helpers).

This also closes the race in the end of close.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Samuel Ortiz <samuel@sortiz.org>
Cc: netdev@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jiri Slaby 2012-06-04 13:35:20 +02:00 committed by Greg Kroah-Hartman
parent 849d5a997f
commit e673927d8a
2 changed files with 18 additions and 21 deletions
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1
include/net/irda/ircomm_tty.h
View File

@ -96,7 +96,6 @@ struct ircomm_tty_cb {
struct work_struct tqueue;
/* Protect concurent access to :
* o self->open_count
* o self->ctrl_skb
* o self->tx_skb
* Maybe other things may gain to be protected as well...

38
net/irda/ircomm/ircomm_tty.c
View File

@ -283,13 +283,12 @@ static int ircomm_tty_block_til_ready(struct ircomm_tty_cb *self,
IRDA_DEBUG(2, "%s(%d):block_til_ready before block on %s open_count=%d\n",
__FILE__, __LINE__, tty->driver->name, self->port.count);
/* As far as I can see, we protect port.count - Jean II */
spin_lock_irqsave(&self->spinlock, flags);
spin_lock_irqsave(&self->port.lock, flags);
if (!tty_hung_up_p(filp)) {
extra_count = 1;
self->port.count--;
}
spin_unlock_irqrestore(&self->spinlock, flags);
spin_unlock_irqrestore(&self->port.lock, flags);
self->port.blocked_open++;
while (1) {
@ -340,9 +339,9 @@ static int ircomm_tty_block_til_ready(struct ircomm_tty_cb *self,
if (extra_count) {
/* ++ is not atomic, so this should be protected - Jean II */
spin_lock_irqsave(&self->spinlock, flags);
spin_lock_irqsave(&self->port.lock, flags);
self->port.count++;
spin_unlock_irqrestore(&self->spinlock, flags);
spin_unlock_irqrestore(&self->port.lock, flags);
}
self->port.blocked_open--;
@ -409,12 +408,12 @@ static int ircomm_tty_open(struct tty_struct *tty, struct file *filp)
hashbin_insert(ircomm_tty, (irda_queue_t *) self, line, NULL);
}
/* ++ is not atomic, so this should be protected - Jean II */
spin_lock_irqsave(&self->spinlock, flags);
spin_lock_irqsave(&self->port.lock, flags);
self->port.count++;
tty->driver_data = self;
self->tty = tty;
spin_unlock_irqrestore(&self->spinlock, flags);
spin_unlock_irqrestore(&self->port.lock, flags);
IRDA_DEBUG(1, "%s(), %s%d, count = %d\n", __func__ , tty->driver->name,
self->line, self->port.count);
@ -495,10 +494,10 @@ static void ircomm_tty_close(struct tty_struct *tty, struct file *filp)
IRDA_ASSERT(self != NULL, return;);
IRDA_ASSERT(self->magic == IRCOMM_TTY_MAGIC, return;);
spin_lock_irqsave(&self->spinlock, flags);
spin_lock_irqsave(&self->port.lock, flags);
if (tty_hung_up_p(filp)) {
spin_unlock_irqrestore(&self->spinlock, flags);
spin_unlock_irqrestore(&self->port.lock, flags);
IRDA_DEBUG(0, "%s(), returning 1\n", __func__ );
return;
@ -524,20 +523,15 @@ static void ircomm_tty_close(struct tty_struct *tty, struct file *filp)
self->port.count = 0;
}
if (self->port.count) {
spin_unlock_irqrestore(&self->spinlock, flags);
spin_unlock_irqrestore(&self->port.lock, flags);
IRDA_DEBUG(0, "%s(), open count > 0\n", __func__ );
return;
}
/* Hum... Should be test_and_set_bit ??? - Jean II */
set_bit(ASYNCB_CLOSING, &self->port.flags);
/* We need to unlock here (we were unlocking at the end of this
* function), because tty_wait_until_sent() may schedule.
* I don't know if the rest should be protected somehow,
* so someone should check. - Jean II */
spin_unlock_irqrestore(&self->spinlock, flags);
spin_unlock_irqrestore(&self->port.lock, flags);
/*
* Now we wait for the transmit buffer to clear; and we notify
@ -552,16 +546,21 @@ static void ircomm_tty_close(struct tty_struct *tty, struct file *filp)
tty_driver_flush_buffer(tty);
tty_ldisc_flush(tty);
spin_lock_irqsave(&self->port.lock, flags);
tty->closing = 0;
self->tty = NULL;
if (self->port.blocked_open) {
if (self->port.close_delay)
if (self->port.close_delay) {
spin_unlock_irqrestore(&self->port.lock, flags);
schedule_timeout_interruptible(self->port.close_delay);
spin_lock_irqsave(&self->port.lock, flags);
}
wake_up_interruptible(&self->port.open_wait);
}
self->port.flags &= ~(ASYNC_NORMAL_ACTIVE|ASYNC_CLOSING);
spin_unlock_irqrestore(&self->port.lock, flags);
wake_up_interruptible(&self->port.close_wait);
}
@ -1003,12 +1002,11 @@ static void ircomm_tty_hangup(struct tty_struct *tty)
/* ircomm_tty_flush_buffer(tty); */
ircomm_tty_shutdown(self);
/* I guess we need to lock here - Jean II */
spin_lock_irqsave(&self->spinlock, flags);
spin_lock_irqsave(&self->port.lock, flags);
self->port.flags &= ~ASYNC_NORMAL_ACTIVE;
self->tty = NULL;
self->port.count = 0;
spin_unlock_irqrestore(&self->spinlock, flags);
spin_unlock_irqrestore(&self->port.lock, flags);
wake_up_interruptible(&self->port.open_wait);
}