[patch for 2.6.32? 2/2] hso: fix soft-lockup

* [patch for 2.6.32? 2/2] hso: fix soft-lockup
@ 2009-11-17 22:50 akpm
  2009-11-23 18:54 ` David Miller
  0 siblings, 1 reply; 2+ messages in thread
From: akpm @ 2009-11-17 22:50 UTC (permalink / raw)
  To: davem; +Cc: netdev, akpm, antti.kaijanmaki, greg, randy.dunlap, stable

From: Antti Kaijanmäki <antti.kaijanmaki@nomovok.com>

Fix soft-lockup in hso.c which is triggered on SMP machine when
modem is removed while file descriptor(s) under /dev are still open:

  old version called kref_put() too early which resulted in destroying
  hso_serial and hso_device objects which were still used later on.

Signed-off-by: Antti Kaijanmäki <antti.kaijanmaki@nomovok.com>
Cc: Greg KH <greg@kroah.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 drivers/net/usb/hso.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff -puN drivers/net/usb/hso.c~hso-fix-soft-lockup drivers/net/usb/hso.c

--- a/drivers/net/usb/hso.c~hso-fix-soft-lockup
+++ a/drivers/net/usb/hso.c
@@ -1363,7 +1363,7 @@ static void hso_serial_close(struct tty_
 	/* reset the rts and dtr */
 	/* do the actual close */
 	serial->open_count--;
-	kref_put(&serial->parent->ref, hso_serial_ref_free);
+
 	if (serial->open_count <= 0) {
 		serial->open_count = 0;
 		spin_lock_irq(&serial->serial_lock);
@@ -1383,6 +1383,8 @@ static void hso_serial_close(struct tty_
 		usb_autopm_put_interface(serial->parent->interface);
 
 	mutex_unlock(&serial->parent->mutex);
+
+	kref_put(&serial->parent->ref, hso_serial_ref_free);
 }
 
 /* close the requested serial port */
_

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