firewire: sbp2: remove obsolete reference counting
Since commit 0278ccd9d53e07c4e699432b2fed9de6c56f506c "firewire: sbp2:
fix panic after rmmod with slow targets", the lifetime of an sbp2_target
instance does no longer extent past the return of sbp2_remove().
Therefore it is no longer necessary to call fw_unit_get/put() and
fw_device_get/put() in sbp2_probe/remove().
Furthermore, said commit also ensures that lu->work is not going to be
executed or requeued at a time when the sbp2_target is no longer in use.
Hence there is no need for sbp2_target reference counting for lu->work.
Other concurrent contexts:
- Processes which access the sysfs of the SCSI host device or of one
of its subdevices are safe because these interfaces are all removed
by scsi_remove_device/host() in sbp2_release_target().
- SBP-2 command block ORB transactions are finished when
scsi_remove_device() in sbp2_release_target() returns.
- SBP-2 management ORB transactions are finished when
cancel_delayed_work_sync(&lu->work) before sbp2_release_target()
returns.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
diff --git a/drivers/firewire/sbp2.c b/drivers/firewire/sbp2.c
index 17cef86..a2715b2 100644
--- a/drivers/firewire/sbp2.c
+++ b/drivers/firewire/sbp2.c
@@ -159,7 +159,6 @@
* and one struct Scsi_Host per sbp2_target.
*/
struct sbp2_target {
- struct kref kref;
struct fw_unit *unit;
const char *bus_id;
struct list_head lu_list;
@@ -772,9 +771,8 @@
return scsilun_to_int(&eight_bytes_lun);
}
-static void sbp2_release_target(struct kref *kref)
+static void sbp2_release_target(struct sbp2_target *tgt)
{
- struct sbp2_target *tgt = container_of(kref, struct sbp2_target, kref);
struct sbp2_logical_unit *lu, *next;
struct Scsi_Host *shost =
container_of((void *)tgt, struct Scsi_Host, hostdata[0]);
@@ -811,30 +809,12 @@
scsi_remove_host(shost);
fw_notify("released %s, target %d:0:0\n", tgt->bus_id, shost->host_no);
- fw_unit_put(tgt->unit);
scsi_host_put(shost);
- fw_device_put(device);
}
-static void sbp2_target_get(struct sbp2_target *tgt)
-{
- kref_get(&tgt->kref);
-}
-
-static void sbp2_target_put(struct sbp2_target *tgt)
-{
- kref_put(&tgt->kref, sbp2_release_target);
-}
-
-/*
- * Always get the target's kref when scheduling work on one its units.
- * Each workqueue job is responsible to call sbp2_target_put() upon return.
- */
static void sbp2_queue_work(struct sbp2_logical_unit *lu, unsigned long delay)
{
- sbp2_target_get(lu->tgt);
- if (!queue_delayed_work(fw_workqueue, &lu->work, delay))
- sbp2_target_put(lu->tgt);
+ queue_delayed_work(fw_workqueue, &lu->work, delay);
}
/*
@@ -877,7 +857,7 @@
int generation, node_id, local_node_id;
if (fw_device_is_shutdown(device))
- goto out;
+ return;
generation = device->generation;
smp_rmb(); /* node IDs must not be older than generation */
@@ -899,7 +879,7 @@
/* Let any waiting I/O fail from now on. */
sbp2_unblock(lu->tgt);
}
- goto out;
+ return;
}
tgt->node_id = node_id;
@@ -925,7 +905,8 @@
if (lu->has_sdev) {
sbp2_cancel_orbs(lu);
sbp2_conditionally_unblock(lu);
- goto out;
+
+ return;
}
if (lu->tgt->workarounds & SBP2_WORKAROUND_DELAY_INQUIRY)
@@ -957,7 +938,8 @@
lu->has_sdev = true;
scsi_device_put(sdev);
sbp2_allow_block(lu);
- goto out;
+
+ return;
out_logout_login:
smp_rmb(); /* generation may have changed */
@@ -971,8 +953,6 @@
* lu->work already. Reset the work from reconnect to login.
*/
PREPARE_DELAYED_WORK(&lu->work, sbp2_login);
- out:
- sbp2_target_put(tgt);
}
static int sbp2_add_logical_unit(struct sbp2_target *tgt, int lun_entry)
@@ -1141,7 +1121,6 @@
tgt = (struct sbp2_target *)shost->hostdata;
dev_set_drvdata(&unit->device, tgt);
tgt->unit = unit;
- kref_init(&tgt->kref);
INIT_LIST_HEAD(&tgt->lu_list);
tgt->bus_id = dev_name(&unit->device);
tgt->guid = (u64)device->config_rom[3] << 32 | device->config_rom[4];
@@ -1154,9 +1133,6 @@
if (scsi_add_host(shost, &unit->device) < 0)
goto fail_shost_put;
- fw_device_get(device);
- fw_unit_get(unit);
-
/* implicit directory ID */
tgt->directory_id = ((unit->directory - device->config_rom) * 4
+ CSR_CONFIG_ROM) & 0xffffff;
@@ -1166,7 +1142,7 @@
if (sbp2_scan_unit_dir(tgt, unit->directory, &model,
&firmware_revision) < 0)
- goto fail_tgt_put;
+ goto fail_release_target;
sbp2_clamp_management_orb_timeout(tgt);
sbp2_init_workarounds(tgt, model, firmware_revision);
@@ -1183,10 +1159,11 @@
/* Do the login in a workqueue so we can easily reschedule retries. */
list_for_each_entry(lu, &tgt->lu_list, link)
sbp2_queue_work(lu, DIV_ROUND_UP(HZ, 5));
+
return 0;
- fail_tgt_put:
- sbp2_target_put(tgt);
+ fail_release_target:
+ sbp2_release_target(tgt);
return -ENOMEM;
fail_shost_put:
@@ -1203,7 +1180,8 @@
list_for_each_entry(lu, &tgt->lu_list, link)
cancel_delayed_work_sync(&lu->work);
- sbp2_target_put(tgt);
+ sbp2_release_target(tgt);
+
return 0;
}
@@ -1216,7 +1194,7 @@
int generation, node_id, local_node_id;
if (fw_device_is_shutdown(device))
- goto out;
+ return;
generation = device->generation;
smp_rmb(); /* node IDs must not be older than generation */
@@ -1241,7 +1219,8 @@
PREPARE_DELAYED_WORK(&lu->work, sbp2_login);
}
sbp2_queue_work(lu, DIV_ROUND_UP(HZ, 5));
- goto out;
+
+ return;
}
tgt->node_id = node_id;
@@ -1255,8 +1234,6 @@
sbp2_agent_reset(lu);
sbp2_cancel_orbs(lu);
sbp2_conditionally_unblock(lu);
- out:
- sbp2_target_put(tgt);
}
static void sbp2_update(struct fw_unit *unit)
