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authorAlan Cox <alan@linux.intel.com>2010-02-08 10:07:04 +0000
committerGreg Kroah-Hartman <gregkh@suse.de>2010-03-02 14:43:20 -0800
commite8c65d143a9903cb553c0d80c819428c5b839a02 (patch)
tree58cea659ac19c23a4c5475a362c157c9497ef10f /drivers/char
parent266794eb71cfee65b38371954b9db2f6dbda207c (diff)
downloadlinux-e8c65d143a9903cb553c0d80c819428c5b839a02.tar.bz2
nozomi: Fix mutex handling
The original author didn't realise the kernel lock was a drop while sleep lock so did clever (and wrong) things to work around the non need to avoid deadlocks. Remove the cleverness and the comment (as we don't hold the BKL now anyway in those paths) Signed-off-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/char')
-rw-r--r--drivers/char/nozomi.c34
1 files changed, 12 insertions, 22 deletions
diff --git a/drivers/char/nozomi.c b/drivers/char/nozomi.c
index cd405bcf53a6..fac9157a0ec0 100644
--- a/drivers/char/nozomi.c
+++ b/drivers/char/nozomi.c
@@ -1693,15 +1693,7 @@ static int ntty_write(struct tty_struct *tty, const unsigned char *buffer,
if (!dc || !port)
return -ENODEV;
- if (unlikely(!mutex_trylock(&port->tty_sem))) {
- /*
- * must test lock as tty layer wraps calls
- * to this function with BKL
- */
- dev_err(&dc->pdev->dev, "Would have deadlocked - "
- "return EAGAIN\n");
- return -EAGAIN;
- }
+ mutex_lock(&port->tty_sem);
if (unlikely(!port->port.count)) {
DBG1(" ");
@@ -1741,25 +1733,23 @@ exit:
* This method is called by the upper tty layer.
* #according to sources N_TTY.c it expects a value >= 0 and
* does not check for negative values.
+ *
+ * If the port is unplugged report lots of room and let the bits
+ * dribble away so we don't block anything.
*/
static int ntty_write_room(struct tty_struct *tty)
{
struct port *port = tty->driver_data;
- int room = 0;
+ int room = 4096;
const struct nozomi *dc = get_dc_by_tty(tty);
- if (!dc || !port)
- return 0;
- if (!mutex_trylock(&port->tty_sem))
- return 0;
-
- if (!port->port.count)
- goto exit;
-
- room = port->fifo_ul.size - kfifo_len(&port->fifo_ul);
-
-exit:
- mutex_unlock(&port->tty_sem);
+ if (dc) {
+ mutex_lock(&port->tty_sem);
+ if (port->port.count)
+ room = port->fifo_ul.size -
+ kfifo_len(&port->fifo_ul);
+ mutex_unlock(&port->tty_sem);
+ }
return room;
}