diff options
| -rw-r--r-- | drivers/s390/block/dasd_alias.c | 235 |
1 files changed, 152 insertions, 83 deletions
diff --git a/drivers/s390/block/dasd_alias.c b/drivers/s390/block/dasd_alias.c index 286782c60da4..cbbdd3e7fea1 100644 --- a/drivers/s390/block/dasd_alias.c +++ b/drivers/s390/block/dasd_alias.c @@ -319,22 +319,14 @@ static int _add_device_to_lcu(struct alias_lcu *lcu, struct dasd_eckd_private *private; struct alias_pav_group *group; struct dasd_uid uid; - unsigned long flags; private = (struct dasd_eckd_private *) device->private; - /* only lock if not already locked */ - if (device != pos) - spin_lock_irqsave_nested(get_ccwdev_lock(device->cdev), flags, - CDEV_NESTED_SECOND); private->uid.type = lcu->uac->unit[private->uid.real_unit_addr].ua_type; private->uid.base_unit_addr = lcu->uac->unit[private->uid.real_unit_addr].base_ua; uid = private->uid; - if (device != pos) - spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags); - /* if we have no PAV anyway, we don't need to bother with PAV groups */ if (lcu->pav == NO_PAV) { list_move(&device->alias_list, &lcu->active_devices); @@ -411,6 +403,130 @@ suborder_not_supported(struct dasd_ccw_req *cqr) return 0; } +/* + * This function tries to lock all devices on an lcu via trylock + * return NULL on success otherwise return first failed device + */ +static struct dasd_device *_trylock_all_devices_on_lcu(struct alias_lcu *lcu, + struct dasd_device *pos) + +{ + struct alias_pav_group *pavgroup; + struct dasd_device *device; + + list_for_each_entry(device, &lcu->active_devices, alias_list) { + if (device == pos) + continue; + if (!spin_trylock(get_ccwdev_lock(device->cdev))) + return device; + } + list_for_each_entry(device, &lcu->inactive_devices, alias_list) { + if (device == pos) + continue; + if (!spin_trylock(get_ccwdev_lock(device->cdev))) + return device; + } + list_for_each_entry(pavgroup, &lcu->grouplist, group) { + list_for_each_entry(device, &pavgroup->baselist, alias_list) { + if (device == pos) + continue; + if (!spin_trylock(get_ccwdev_lock(device->cdev))) + return device; + } + list_for_each_entry(device, &pavgroup->aliaslist, alias_list) { + if (device == pos) + continue; + if (!spin_trylock(get_ccwdev_lock(device->cdev))) + return device; + } + } + return NULL; +} + +/* + * unlock all devices except the one that is specified as pos + * stop if enddev is specified and reached + */ +static void _unlock_all_devices_on_lcu(struct alias_lcu *lcu, + struct dasd_device *pos, + struct dasd_device *enddev) + +{ + struct alias_pav_group *pavgroup; + struct dasd_device *device; + + list_for_each_entry(device, &lcu->active_devices, alias_list) { + if (device == pos) + continue; + if (device == enddev) + return; + spin_unlock(get_ccwdev_lock(device->cdev)); + } + list_for_each_entry(device, &lcu->inactive_devices, alias_list) { + if (device == pos) + continue; + if (device == enddev) + return; + spin_unlock(get_ccwdev_lock(device->cdev)); + } + list_for_each_entry(pavgroup, &lcu->grouplist, group) { + list_for_each_entry(device, &pavgroup->baselist, alias_list) { + if (device == pos) + continue; + if (device == enddev) + return; + spin_unlock(get_ccwdev_lock(device->cdev)); + } + list_for_each_entry(device, &pavgroup->aliaslist, alias_list) { + if (device == pos) + continue; + if (device == enddev) + return; + spin_unlock(get_ccwdev_lock(device->cdev)); + } + } +} + +/* + * this function is needed because the locking order + * device lock -> lcu lock + * needs to be assured when iterating over devices in an LCU + * + * if a device is specified in pos then the device lock is already hold + */ +static void _trylock_and_lock_lcu_irqsave(struct alias_lcu *lcu, + struct dasd_device *pos, + unsigned long *flags) +{ + struct dasd_device *failed; + + do { + spin_lock_irqsave(&lcu->lock, *flags); + failed = _trylock_all_devices_on_lcu(lcu, pos); + if (failed) { + _unlock_all_devices_on_lcu(lcu, pos, failed); + spin_unlock_irqrestore(&lcu->lock, *flags); + cpu_relax(); + } + } while (failed); +} + +static void _trylock_and_lock_lcu(struct alias_lcu *lcu, + struct dasd_device *pos) +{ + struct dasd_device *failed; + + do { + spin_lock(&lcu->lock); + failed = _trylock_all_devices_on_lcu(lcu, pos); + if (failed) { + _unlock_all_devices_on_lcu(lcu, pos, failed); + spin_unlock(&lcu->lock); + cpu_relax(); + } + } while (failed); +} + static int read_unit_address_configuration(struct dasd_device *device, struct alias_lcu *lcu) { @@ -505,10 +621,7 @@ static int _lcu_update(struct dasd_device *refdev, struct alias_lcu *lcu) if (rc) return rc; - /* need to take cdev lock before lcu lock */ - spin_lock_irqsave_nested(get_ccwdev_lock(refdev->cdev), flags, - CDEV_NESTED_FIRST); - spin_lock(&lcu->lock); + _trylock_and_lock_lcu_irqsave(lcu, NULL, &flags); lcu->pav = NO_PAV; for (i = 0; i < MAX_DEVICES_PER_LCU; ++i) { switch (lcu->uac->unit[i].ua_type) { @@ -527,8 +640,8 @@ static int _lcu_update(struct dasd_device *refdev, struct alias_lcu *lcu) alias_list) { _add_device_to_lcu(lcu, device, refdev); } - spin_unlock(&lcu->lock); - spin_unlock_irqrestore(get_ccwdev_lock(refdev->cdev), flags); + _unlock_all_devices_on_lcu(lcu, NULL, NULL); + spin_unlock_irqrestore(&lcu->lock, flags); return 0; } @@ -616,8 +729,6 @@ int dasd_alias_add_device(struct dasd_device *device) private = (struct dasd_eckd_private *) device->private; lcu = private->lcu; rc = 0; - - /* need to take cdev lock before lcu lock */ spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags); spin_lock(&lcu->lock); if (!(lcu->flags & UPDATE_PENDING)) { @@ -754,30 +865,19 @@ static void _restart_all_base_devices_on_lcu(struct alias_lcu *lcu) struct alias_pav_group *pavgroup; struct dasd_device *device; struct dasd_eckd_private *private; - unsigned long flags; /* active and inactive list can contain alias as well as base devices */ list_for_each_entry(device, &lcu->active_devices, alias_list) { private = (struct dasd_eckd_private *) device->private; - spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags); - if (private->uid.type != UA_BASE_DEVICE) { - spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), - flags); + if (private->uid.type != UA_BASE_DEVICE) continue; - } - spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags); dasd_schedule_block_bh(device->block); dasd_schedule_device_bh(device); } list_for_each_entry(device, &lcu->inactive_devices, alias_list) { private = (struct dasd_eckd_private *) device->private; - spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags); - if (private->uid.type != UA_BASE_DEVICE) { - spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), - flags); + if (private->uid.type != UA_BASE_DEVICE) continue; - } - spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags); dasd_schedule_block_bh(device->block); dasd_schedule_device_bh(device); } @@ -841,38 +941,20 @@ static void flush_all_alias_devices_on_lcu(struct alias_lcu *lcu) spin_unlock_irqrestore(&lcu->lock, flags); } -static void __stop_device_on_lcu(struct dasd_device *device, - struct dasd_device *pos) -{ - /* If pos == device then device is already locked! */ - if (pos == device) { - dasd_device_set_stop_bits(pos, DASD_STOPPED_SU); - return; - } - spin_lock(get_ccwdev_lock(pos->cdev)); - dasd_device_set_stop_bits(pos, DASD_STOPPED_SU); - spin_unlock(get_ccwdev_lock(pos->cdev)); -} - -/* - * This function is called in interrupt context, so the - * cdev lock for device is already locked! - */ -static void _stop_all_devices_on_lcu(struct alias_lcu *lcu, - struct dasd_device *device) +static void _stop_all_devices_on_lcu(struct alias_lcu *lcu) { struct alias_pav_group *pavgroup; - struct dasd_device *pos; + struct dasd_device *device; - list_for_each_entry(pos, &lcu->active_devices, alias_list) - __stop_device_on_lcu(device, pos); - list_for_each_entry(pos, &lcu->inactive_devices, alias_list) - __stop_device_on_lcu(device, pos); + list_for_each_entry(device, &lcu->active_devices, alias_list) + dasd_device_set_stop_bits(device, DASD_STOPPED_SU); + list_for_each_entry(device, &lcu->inactive_devices, alias_list) + dasd_device_set_stop_bits(device, DASD_STOPPED_SU); list_for_each_entry(pavgroup, &lcu->grouplist, group) { - list_for_each_entry(pos, &pavgroup->baselist, alias_list) - __stop_device_on_lcu(device, pos); - list_for_each_entry(pos, &pavgroup->aliaslist, alias_list) - __stop_device_on_lcu(device, pos); + list_for_each_entry(device, &pavgroup->baselist, alias_list) + dasd_device_set_stop_bits(device, DASD_STOPPED_SU); + list_for_each_entry(device, &pavgroup->aliaslist, alias_list) + dasd_device_set_stop_bits(device, DASD_STOPPED_SU); } } @@ -880,33 +962,16 @@ static void _unstop_all_devices_on_lcu(struct alias_lcu *lcu) { struct alias_pav_group *pavgroup; struct dasd_device *device; - unsigned long flags; - list_for_each_entry(device, &lcu->active_devices, alias_list) { - spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags); + list_for_each_entry(device, &lcu->active_devices, alias_list) dasd_device_remove_stop_bits(device, DASD_STOPPED_SU); - spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags); - } - - list_for_each_entry(device, &lcu->inactive_devices, alias_list) { - spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags); + list_for_each_entry(device, &lcu->inactive_devices, alias_list) dasd_device_remove_stop_bits(device, DASD_STOPPED_SU); - spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags); - } - list_for_each_entry(pavgroup, &lcu->grouplist, group) { - list_for_each_entry(device, &pavgroup->baselist, alias_list) { - spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags); + list_for_each_entry(device, &pavgroup->baselist, alias_list) dasd_device_remove_stop_bits(device, DASD_STOPPED_SU); - spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), - flags); - } - list_for_each_entry(device, &pavgroup->aliaslist, alias_list) { - spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags); + list_for_each_entry(device, &pavgroup->aliaslist, alias_list) dasd_device_remove_stop_bits(device, DASD_STOPPED_SU); - spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), - flags); - } } } @@ -932,13 +997,14 @@ static void summary_unit_check_handling_work(struct work_struct *work) spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags); reset_summary_unit_check(lcu, device, suc_data->reason); - spin_lock_irqsave(&lcu->lock, flags); + _trylock_and_lock_lcu_irqsave(lcu, NULL, &flags); _unstop_all_devices_on_lcu(lcu); _restart_all_base_devices_on_lcu(lcu); /* 3. read new alias configuration */ _schedule_lcu_update(lcu, device); lcu->suc_data.device = NULL; dasd_put_device(device); + _unlock_all_devices_on_lcu(lcu, NULL, NULL); spin_unlock_irqrestore(&lcu->lock, flags); } @@ -974,10 +1040,7 @@ void dasd_alias_handle_summary_unit_check(struct dasd_device *device, " unit check (no lcu structure)"); return; } - spin_lock(&lcu->lock); - _stop_all_devices_on_lcu(lcu, device); - /* prepare for lcu_update */ - private->lcu->flags |= NEED_UAC_UPDATE | UPDATE_PENDING; + _trylock_and_lock_lcu(lcu, device); /* If this device is about to be removed just return and wait for * the next interrupt on a different device */ @@ -985,6 +1048,7 @@ void dasd_alias_handle_summary_unit_check(struct dasd_device *device, DBF_DEV_EVENT(DBF_WARNING, device, "%s", "device is in offline processing," " don't do summary unit check handling"); + _unlock_all_devices_on_lcu(lcu, device, NULL); spin_unlock(&lcu->lock); return; } @@ -993,12 +1057,17 @@ void dasd_alias_handle_summary_unit_check(struct dasd_device *device, DBF_DEV_EVENT(DBF_WARNING, device, "%s", "previous instance of summary unit check worker" " still pending"); + _unlock_all_devices_on_lcu(lcu, device, NULL); spin_unlock(&lcu->lock); return ; } + _stop_all_devices_on_lcu(lcu); + /* prepare for lcu_update */ + private->lcu->flags |= NEED_UAC_UPDATE | UPDATE_PENDING; lcu->suc_data.reason = reason; lcu->suc_data.device = device; dasd_get_device(device); + _unlock_all_devices_on_lcu(lcu, device, NULL); spin_unlock(&lcu->lock); if (!schedule_work(&lcu->suc_data.worker)) dasd_put_device(device); |