[GIT PULL] FireWire update

Stefan Richter
2007-11-07T01:21:29Z

to receive the following fix for a regression since 2.6.24-rc1.
(Or apply from this e-mail.)

drivers/firewire/fw-sbp2.c | 11 +++++++----
1 files changed, 7 insertions(+), 4 deletions(-)

Stefan Richter (1):
firewire: fw-sbp2: fix refcounting

Full log and diff:

commit 7c45d1913f0a1d597eb4bc3b2c962bc2967da9ea
Author: Stefan Richter <stefanr@s5r6.in-berlin.de>
Date: Wed Nov 7 01:11:56 2007 +0100

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>

diff --git a/drivers/firewire/fw-sbp2.c b/drivers/firewire/fw-sbp2.c
index 5596df6..624ff3e 100644
--- a/drivers/firewire/fw-sbp2.c
+++ b/drivers/firewire/fw-sbp2.c
@@ -650,13 +650,14 @@ static void sbp2_login(struct work_struct *work)
if (sbp2_send_management_orb(lu, node_id, generation,
SBP2_LOGIN_REQUEST, lu->lun, &response) < 0) {
if (lu->retries++ < 5) {
- queue_delayed_work(sbp2_wq, &lu->work,
- DIV_ROUND_UP(HZ, 5));
+ if (queue_delayed_work(sbp2_wq, &lu->work,
+ DIV_ROUND_UP(HZ, 5)))
+ kref_get(&lu->tgt->kref);
} else {
fw_error("failed to login to %s LUN %04x\n",
unit->device.bus_id, lu->lun);
- kref_put(&lu->tgt->kref, sbp2_release_target);
}
+ kref_put(&lu->tgt->kref, sbp2_release_target);
return;
}

@@ -914,7 +915,9 @@ static void sbp2_reconnect(struct work_struct *work)
lu->retries = 0;
PREPARE_DELAYED_WORK(&lu->work, sbp2_login);
}
- queue_delayed_work(sbp2_wq, &lu->work, DIV_ROUND_UP(HZ, 5));
+ if (queue_delayed_work(sbp2_wq, &lu->work, DIV_ROUND_UP(HZ, 5)))
+ kref_get(&lu->tgt->kref);
+ kref_put(&lu->tgt->kref, sbp2_release_target);
return;
}

--
Stefan Richter
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