Commit c45d6320 ("fix reference counting of ftdi_private") stopped
ftdi_sio_port_remove() from directly freeing the port-private data, with
the intention if the port was still open, it would be freed when
ftdi_close() is eventually called and releases the last refcount on the
structure.
That's all very well, but ftdi_sio_port_remove() still contains a call
to usb_set_serial_port_data(port, NULL) -- so by the time we get to
ftdi_close() for the port which was unplugged, it _still_ oopses on
dereferencing that NULL pointer, as it did before (and does in 2.6.29).
The fix is just not to clear the private data in ftdi_sio_port_remove().
Then the refcount is properly reduced to zero when the final kref_put()
happens in ftdi_close().
Remove a bogus comment too, while we're at it. And stop doing things
inside "if (priv)" -- it must _always_ be there.
Based loosely on an earlier patch by Daniel Mack, and suggestions by
Alan Stern.
Signed-off-by: David Woodhouse <David.Woodhouse@xxxxxxxxx>
Tested-by: Daniel Mack <daniel@xxxxxxxx>
Cc: stable@xxxxxxxxxx
---
Commit c45d6320, on which this depends, was already submitted to stable.
diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index 0ab8474..452a61c 100644
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -1487,14 +1488,7 @@ static int ftdi_sio_port_remove(struct usb_serial_port *port)
remove_sysfs_attrs(port);
- /* all open ports are closed at this point
- * (by usbserial.c:__serial_close, which calls ftdi_close)
- */
-
- if (priv) {
- usb_set_serial_port_data(port, NULL);
- kref_put(&priv->kref, ftdi_sio_priv_release);
- }
+ kref_put(&priv->kref, ftdi_sio_priv_release);
return 0;
}
--
David Woodhouse Open Source Technology Centre
David.Woodhouse@xxxxxxxxx Intel Corporation
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