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authorStefan Richter <stefanr@s5r6.in-berlin.de>2007-11-07 01:11:56 +0100
committerStefan Richter <stefanr@s5r6.in-berlin.de>2007-11-07 01:59:28 +0100
commit7c45d1913f0a1d597eb4bc3b2c962bc2967da9ea (patch)
tree49a6bd70e0d221ba6456d6a3c2e403e7d5f5bfaf /drivers/firewire
parentdbeeb816e805091e7cfc03baf36dc40b4adb2bbd (diff)
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>
Diffstat (limited to 'drivers/firewire')
-rw-r--r--drivers/firewire/fw-sbp2.c11
1 files changed, 7 insertions, 4 deletions
diff --git a/drivers/firewire/fw-sbp2.c b/drivers/firewire/fw-sbp2.c
index 5596df65c8ed..624ff3e082f6 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;
}