firewire: fw-sbp2: fix refcounting
Since patch "fw-sbp2: use an own workqueue (fix system responsiveness)"
increased parallelism between fw-sbp2 and fw-core, it was possible that
fw-sbp2 didn't release the SCSI device when the FireWire device was
disconnected.
This happened if sbp2_update() ran during sbp2_login(), because a bus
reset occurred during sbp2_login(). The sbp2_login() work would [try
to] reschedule itself because it failed due to the bus reset, and it
would _not_ drop its reference on the target. However, sbp2_update()
would schedule sbp2_login() too before sbp2_login() rescheduled itself
and hence sbp2_update() would take an additional reference. And then
we would have one reference too many.
The fix is to _always_ drop the reference when leaving the sbp2_login()
work. If the sbp2_login() work reschedules itself, it takes a
reference, but only if it wasn't already rescheduled by sbp2_update().
Ditto in the sbp2_reconnect() work.
The resulting code is actually simpler than before: We _always_ take
a reference when successfully scheduling work. And we _always_ drop
a reference when leaving a workqueue job. No exceptions.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
1 file changed