From a4ed2e737cb73e4405a3649f8aef7619b99fecae Mon Sep 17 00:00:00 2001 From: Peter Hurley Date: Tue, 5 Mar 2013 06:09:04 +0000 Subject: net/irda: Fix port open counts Saving the port count bump is unsafe. If the tty is hung up while this open was blocking, the port count is zeroed. Explicitly check if the tty was hung up while blocking, and correct the port count if not. Signed-off-by: Peter Hurley Signed-off-by: David S. Miller --- net/irda/ircomm/ircomm_tty.c | 14 +++++--------- 1 file changed, 5 insertions(+), 9 deletions(-) (limited to 'net/irda') diff --git a/net/irda/ircomm/ircomm_tty.c b/net/irda/ircomm/ircomm_tty.c index 9a5fd3c3e530..1721dc7e4315 100644 --- a/net/irda/ircomm/ircomm_tty.c +++ b/net/irda/ircomm/ircomm_tty.c @@ -280,7 +280,7 @@ static int ircomm_tty_block_til_ready(struct ircomm_tty_cb *self, struct tty_port *port = &self->port; DECLARE_WAITQUEUE(wait, current); int retval; - int do_clocal = 0, extra_count = 0; + int do_clocal = 0; unsigned long flags; IRDA_DEBUG(2, "%s()\n", __func__ ); @@ -315,10 +315,8 @@ static int ircomm_tty_block_til_ready(struct ircomm_tty_cb *self, __FILE__, __LINE__, tty->driver->name, port->count); spin_lock_irqsave(&port->lock, flags); - if (!tty_hung_up_p(filp)) { - extra_count = 1; + if (!tty_hung_up_p(filp)) port->count--; - } spin_unlock_irqrestore(&port->lock, flags); port->blocked_open++; @@ -361,12 +359,10 @@ static int ircomm_tty_block_til_ready(struct ircomm_tty_cb *self, __set_current_state(TASK_RUNNING); remove_wait_queue(&port->open_wait, &wait); - if (extra_count) { - /* ++ is not atomic, so this should be protected - Jean II */ - spin_lock_irqsave(&port->lock, flags); + spin_lock_irqsave(&port->lock, flags); + if (!tty_hung_up_p(filp)) port->count++; - spin_unlock_irqrestore(&port->lock, flags); - } + spin_unlock_irqrestore(&port->lock, flags); port->blocked_open--; IRDA_DEBUG(1, "%s(%d):block_til_ready after blocking on %s open_count=%d\n", -- cgit v1.2.3 From 2f7c069b96ed7b1f6236f2fa7b0bc06f4f54f2d9 Mon Sep 17 00:00:00 2001 From: Peter Hurley Date: Tue, 5 Mar 2013 06:09:05 +0000 Subject: net/irda: Hold port lock while bumping blocked_open Although tty_lock() already protects concurrent update to blocked_open, that fails to meet the separation-of-concerns between tty_port and tty. Signed-off-by: Peter Hurley Signed-off-by: David S. Miller --- net/irda/ircomm/ircomm_tty.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'net/irda') diff --git a/net/irda/ircomm/ircomm_tty.c b/net/irda/ircomm/ircomm_tty.c index 1721dc7e4315..d282bbea710e 100644 --- a/net/irda/ircomm/ircomm_tty.c +++ b/net/irda/ircomm/ircomm_tty.c @@ -317,8 +317,8 @@ static int ircomm_tty_block_til_ready(struct ircomm_tty_cb *self, spin_lock_irqsave(&port->lock, flags); if (!tty_hung_up_p(filp)) port->count--; - spin_unlock_irqrestore(&port->lock, flags); port->blocked_open++; + spin_unlock_irqrestore(&port->lock, flags); while (1) { if (tty->termios.c_cflag & CBAUD) @@ -362,8 +362,8 @@ static int ircomm_tty_block_til_ready(struct ircomm_tty_cb *self, spin_lock_irqsave(&port->lock, flags); if (!tty_hung_up_p(filp)) port->count++; - spin_unlock_irqrestore(&port->lock, flags); port->blocked_open--; + spin_unlock_irqrestore(&port->lock, flags); IRDA_DEBUG(1, "%s(%d):block_til_ready after blocking on %s open_count=%d\n", __FILE__, __LINE__, tty->driver->name, port->count); -- cgit v1.2.3 From 0b176ce3a7cbfa92eceddf3896f1a504877d974a Mon Sep 17 00:00:00 2001 From: Peter Hurley Date: Tue, 5 Mar 2013 06:09:06 +0000 Subject: net/irda: Use barrier to set task state Without a memory and compiler barrier, the task state change can migrate relative to the condition testing in a blocking loop. However, the task state change must be visible across all cpus prior to testing those conditions. Failing to do this can result in the familiar 'lost wakeup' and this task will hang until killed. Signed-off-by: Peter Hurley Signed-off-by: David S. Miller --- net/irda/ircomm/ircomm_tty.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/irda') diff --git a/net/irda/ircomm/ircomm_tty.c b/net/irda/ircomm/ircomm_tty.c index d282bbea710e..522543d9264a 100644 --- a/net/irda/ircomm/ircomm_tty.c +++ b/net/irda/ircomm/ircomm_tty.c @@ -324,7 +324,7 @@ static int ircomm_tty_block_til_ready(struct ircomm_tty_cb *self, if (tty->termios.c_cflag & CBAUD) tty_port_raise_dtr_rts(port); - current->state = TASK_INTERRUPTIBLE; + set_current_state(TASK_INTERRUPTIBLE); if (tty_hung_up_p(filp) || !test_bit(ASYNCB_INITIALIZED, &port->flags)) { -- cgit v1.2.3 From f74861ca87264e594e0134e8ac14db06be77fe6f Mon Sep 17 00:00:00 2001 From: Peter Hurley Date: Tue, 5 Mar 2013 06:09:07 +0000 Subject: net/irda: Raise dtr in non-blocking open DTR/RTS need to be raised, regardless of the open() mode, but not if the port has already shutdown. Signed-off-by: Peter Hurley Signed-off-by: David S. Miller --- net/irda/ircomm/ircomm_tty.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) (limited to 'net/irda') diff --git a/net/irda/ircomm/ircomm_tty.c b/net/irda/ircomm/ircomm_tty.c index 522543d9264a..362ba47968e4 100644 --- a/net/irda/ircomm/ircomm_tty.c +++ b/net/irda/ircomm/ircomm_tty.c @@ -289,8 +289,15 @@ static int ircomm_tty_block_til_ready(struct ircomm_tty_cb *self, * If non-blocking mode is set, or the port is not enabled, * then make the check up front and then exit. */ - if (filp->f_flags & O_NONBLOCK || tty->flags & (1 << TTY_IO_ERROR)){ - /* nonblock mode is set or port is not enabled */ + if (test_bit(TTY_IO_ERROR, &tty->flags)) { + port->flags |= ASYNC_NORMAL_ACTIVE; + return 0; + } + + if (filp->f_flags & O_NONBLOCK) { + /* nonblock mode is set */ + if (tty->termios.c_cflag & CBAUD) + tty_port_raise_dtr_rts(port); port->flags |= ASYNC_NORMAL_ACTIVE; IRDA_DEBUG(1, "%s(), O_NONBLOCK requested!\n", __func__ ); return 0; -- cgit v1.2.3