firewire: sbp2: remove obsolete reference counting
Since commit 0278ccd9d5 "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>
This commit is contained in:
Stefan Richter
parent
f39aa30d77
commit
6ff8147d07
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@ -159,7 +159,6 @@ struct sbp2_logical_unit {
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* and one struct Scsi_Host per sbp2_target.
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*/
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struct sbp2_target {
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struct kref kref;
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struct fw_unit *unit;
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const char *bus_id;
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struct list_head lu_list;
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@ -772,9 +771,8 @@ static int sbp2_lun2int(u16 lun)
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return scsilun_to_int(&eight_bytes_lun);
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}
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static void sbp2_release_target(struct kref *kref)
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static void sbp2_release_target(struct sbp2_target *tgt)
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{
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struct sbp2_target *tgt = container_of(kref, struct sbp2_target, kref);
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struct sbp2_logical_unit *lu, *next;
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struct Scsi_Host *shost =
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container_of((void *)tgt, struct Scsi_Host, hostdata[0]);
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@ -811,30 +809,12 @@ static void sbp2_release_target(struct kref *kref)
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scsi_remove_host(shost);
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fw_notify("released %s, target %d:0:0\n", tgt->bus_id, shost->host_no);
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fw_unit_put(tgt->unit);
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scsi_host_put(shost);
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fw_device_put(device);
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}
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static void sbp2_target_get(struct sbp2_target *tgt)
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{
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kref_get(&tgt->kref);
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}
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static void sbp2_target_put(struct sbp2_target *tgt)
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{
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kref_put(&tgt->kref, sbp2_release_target);
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}
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/*
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* Always get the target's kref when scheduling work on one its units.
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* Each workqueue job is responsible to call sbp2_target_put() upon return.
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*/
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static void sbp2_queue_work(struct sbp2_logical_unit *lu, unsigned long delay)
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{
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sbp2_target_get(lu->tgt);
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if (!queue_delayed_work(fw_workqueue, &lu->work, delay))
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sbp2_target_put(lu->tgt);
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queue_delayed_work(fw_workqueue, &lu->work, delay);
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}
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/*
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@ -877,7 +857,7 @@ static void sbp2_login(struct work_struct *work)
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int generation, node_id, local_node_id;
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if (fw_device_is_shutdown(device))
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goto out;
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return;
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generation = device->generation;
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smp_rmb(); /* node IDs must not be older than generation */
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@ -899,7 +879,7 @@ static void sbp2_login(struct work_struct *work)
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/* Let any waiting I/O fail from now on. */
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sbp2_unblock(lu->tgt);
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}
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goto out;
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return;
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}
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tgt->node_id = node_id;
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@ -925,7 +905,8 @@ static void sbp2_login(struct work_struct *work)
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if (lu->has_sdev) {
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sbp2_cancel_orbs(lu);
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sbp2_conditionally_unblock(lu);
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goto out;
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return;
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}
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if (lu->tgt->workarounds & SBP2_WORKAROUND_DELAY_INQUIRY)
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@ -957,7 +938,8 @@ static void sbp2_login(struct work_struct *work)
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lu->has_sdev = true;
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scsi_device_put(sdev);
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sbp2_allow_block(lu);
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goto out;
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return;
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out_logout_login:
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smp_rmb(); /* generation may have changed */
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@ -971,8 +953,6 @@ static void sbp2_login(struct work_struct *work)
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* lu->work already. Reset the work from reconnect to login.
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*/
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PREPARE_DELAYED_WORK(&lu->work, sbp2_login);
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out:
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sbp2_target_put(tgt);
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}
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static int sbp2_add_logical_unit(struct sbp2_target *tgt, int lun_entry)
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@ -1141,7 +1121,6 @@ static int sbp2_probe(struct device *dev)
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tgt = (struct sbp2_target *)shost->hostdata;
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dev_set_drvdata(&unit->device, tgt);
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tgt->unit = unit;
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kref_init(&tgt->kref);
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INIT_LIST_HEAD(&tgt->lu_list);
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tgt->bus_id = dev_name(&unit->device);
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tgt->guid = (u64)device->config_rom[3] << 32 | device->config_rom[4];
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@ -1154,9 +1133,6 @@ static int sbp2_probe(struct device *dev)
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if (scsi_add_host(shost, &unit->device) < 0)
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goto fail_shost_put;
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fw_device_get(device);
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fw_unit_get(unit);
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/* implicit directory ID */
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tgt->directory_id = ((unit->directory - device->config_rom) * 4
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+ CSR_CONFIG_ROM) & 0xffffff;
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@ -1166,7 +1142,7 @@ static int sbp2_probe(struct device *dev)
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if (sbp2_scan_unit_dir(tgt, unit->directory, &model,
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&firmware_revision) < 0)
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goto fail_tgt_put;
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goto fail_release_target;
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sbp2_clamp_management_orb_timeout(tgt);
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sbp2_init_workarounds(tgt, model, firmware_revision);
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@ -1183,10 +1159,11 @@ static int sbp2_probe(struct device *dev)
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/* Do the login in a workqueue so we can easily reschedule retries. */
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list_for_each_entry(lu, &tgt->lu_list, link)
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sbp2_queue_work(lu, DIV_ROUND_UP(HZ, 5));
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return 0;
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fail_tgt_put:
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sbp2_target_put(tgt);
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fail_release_target:
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sbp2_release_target(tgt);
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return -ENOMEM;
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fail_shost_put:
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@ -1203,7 +1180,8 @@ static int sbp2_remove(struct device *dev)
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list_for_each_entry(lu, &tgt->lu_list, link)
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cancel_delayed_work_sync(&lu->work);
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sbp2_target_put(tgt);
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sbp2_release_target(tgt);
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return 0;
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}
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@ -1216,7 +1194,7 @@ static void sbp2_reconnect(struct work_struct *work)
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int generation, node_id, local_node_id;
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if (fw_device_is_shutdown(device))
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goto out;
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return;
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generation = device->generation;
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smp_rmb(); /* node IDs must not be older than generation */
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@ -1241,7 +1219,8 @@ static void sbp2_reconnect(struct work_struct *work)
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PREPARE_DELAYED_WORK(&lu->work, sbp2_login);
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}
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sbp2_queue_work(lu, DIV_ROUND_UP(HZ, 5));
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goto out;
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return;
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}
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tgt->node_id = node_id;
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@ -1255,8 +1234,6 @@ static void sbp2_reconnect(struct work_struct *work)
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sbp2_agent_reset(lu);
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sbp2_cancel_orbs(lu);
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sbp2_conditionally_unblock(lu);
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out:
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sbp2_target_put(tgt);
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}
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static void sbp2_update(struct fw_unit *unit)
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