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Subject[PATCH 06/24] TTY: ircomm, revamp locking
Date
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
---
include/net/irda/ircomm_tty.h | 1 -
net/irda/ircomm/ircomm_tty.c | 38 ++++++++++++++++++--------------------
2 files changed, 18 insertions(+), 21 deletions(-)
diff --git a/include/net/irda/ircomm_tty.h b/include/net/irda/ircomm_tty.h
index e4db3b5..a9027d8 100644
--- a/include/net/irda/ircomm_tty.h
+++ b/include/net/irda/ircomm_tty.h
@@ -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...
diff --git a/net/irda/ircomm/ircomm_tty.c b/net/irda/ircomm/ircomm_tty.c
index 8e61026..7b2152c 100644
--- a/net/irda/ircomm/ircomm_tty.c
+++ b/net/irda/ircomm/ircomm_tty.c
@@ -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);
}
--
1.7.10.3



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