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Subject[patch 19/87] Fix oops on close of hot-unplugged FTDI serial converter
2.6.29-stable review patch.  If anyone has any objections, please let us know.


From: David Woodhouse <>

commit 80193195f87ebca6d7417516d6edeb3969631c15 upstream.

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

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 <>
Tested-by: Daniel Mack <>
Signed-off-by: Linus Torvalds <>
Signed-off-by: Greg Kroah-Hartman <>

drivers/usb/serial/ftdi_sio.c | 9 +--------
1 file changed, 1 insertion(+), 8 deletions(-)

--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -1485,14 +1485,7 @@ static int ftdi_sio_port_remove(struct u


- /* 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;

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