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libertas USB: don't set surpriseremoved flag

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We found a deadlock in the handling of command failures/reset conditions.
For example:

 1. Two commands are in the queue.
 2. The first command is sent, but causes a timeout, which kicks off an
    asynchronous device reset
 3. The second command is queued (but not yet sent to the hardware)
 4. The device reset kicks in, causing the if_usb disconnect handler to
    set the "surprise removed" flag to be set as the device disappears
    from the bus. This causes lbs_thread to stop processing things
    ("adapter removed; waiting to die"), not processing any further
    commands, leaving the second queued command "in the air", causing a
    deadlock.

Fix this by removing the surpriseremoved flag setting in if_usb. I can't
see any reason why this needs to be done so early. lbs_remove_card will set
this flag at an appropriate time - i.e. after all pending commands have
been completed or cancelled, avoiding this deadlock.

Signed-off-by: Daniel Drake <dsd@laptop.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This commit is contained in:
Daniel Drake 2012-07-15 23:48:00 +01:00 committed by John W. Linville
parent 9c3099f7cb
commit 9ef9dbeaa5
1 changed files with 0 additions and 1 deletions
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1
drivers/net/wireless/libertas/if_usb.c
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@ -309,7 +309,6 @@ static void if_usb_disconnect(struct usb_interface *intf)
cardp->surprise_removed = 1;
if (priv) {
priv->surpriseremoved = 1;
lbs_stop_card(priv);
lbs_remove_card(priv);
}