Patchwork hso: fix soft-lockup

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Submitter Antti Kaijanmäki
Date Oct. 27, 2009, 2:26 p.m.
Message ID <1256653616.3591.114.camel@nomovok.homedomain>
Download mbox | patch
Permalink /patch/36987/
State Changes Requested
Delegated to: David Miller
Headers show

Comments

Antti Kaijanmäki - Oct. 27, 2009, 2:26 p.m.
On Mon, 2009-10-26 at 12:40 -0700, Greg KH wrote:
> Yes, that should be a new patch, especially as it would not be needed
> to fix older kernels for the original bug.
> 
> So, care to send 2 patches?  The debug one isn't needed to be sent to
> the stable@kernel.org address.


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>
---
 drivers/net/usb/hso.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

Patch

diff --git a/drivers/net/usb/hso.c b/drivers/net/usb/hso.c
index 746839b..43bc3fc 100644
--- a/drivers/net/usb/hso.c
+++ b/drivers/net/usb/hso.c
@@ -1363,7 +1363,7 @@  static void hso_serial_close(struct tty_struct *tty, struct file *filp)
 	/* 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_struct *tty, struct file *filp)
 		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 */