firewire: sbp2: fix panic after rmmod with slow targets

If firewire-sbp2 starts a login to a target that doesn't complete ORBs
in a timely manner (and has to retry the login), and the module is
removed before the operation times out, you end up with a null-pointer
dereference and a kernel panic.

[SR:  This happens because sbp2_target_get/put() do not maintain
module references.  scsi_device_get/put() do, but at occasions like
Chris describes one, nobody holds a reference to an SBP-2 sdev.]

This patch cancels pending work for each unit in sbp2_remove(), which
hopefully means there are no extra references around that prevent us
from unloading. This fixes my crash.

Signed-off-by: Chris Boot <bootc@bootc.net>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

diff --git a/drivers/firewire/sbp2.c b/drivers/firewire/sbp2.c
index 41841a3..17cef86 100644 (file)
--- a/drivers/firewire/sbp2.c
+++ b/drivers/firewire/sbp2.c
@@ -1198,6 +1198,10 @@ static int sbp2_remove(struct device *dev)
 {
        struct fw_unit *unit = fw_unit(dev);
        struct sbp2_target *tgt = dev_get_drvdata(&unit->device);
+       struct sbp2_logical_unit *lu;
+
+       list_for_each_entry(lu, &tgt->lu_list, link)
+               cancel_delayed_work_sync(&lu->work);
 
        sbp2_target_put(tgt);
        return 0;