From 765cbc6dad16b87724803e359d6be792ddf08614 Mon Sep 17 00:00:00 2001 From: Hannes Reinecke Date: Thu, 17 Jul 2008 16:52:51 -0700 Subject: [SCSI] scsi_dh: Implement common device table handling Instead of having each and every driver implement its own device table scanning code we should rather implement a common routine and scan the device tables there. This allows us also to implement a general notifier chain callback for all device handler instead for one per handler. [sekharan: Fix rejections caused by conflicting bug fix] Signed-off-by: Hannes Reinecke Signed-off-by: Chandra Seetharaman Signed-off-by: James Bottomley --- drivers/scsi/device_handler/scsi_dh.c | 202 ++++++++++++++++++++++++++++------ 1 file changed, 170 insertions(+), 32 deletions(-) (limited to 'drivers/scsi/device_handler/scsi_dh.c') diff --git a/drivers/scsi/device_handler/scsi_dh.c b/drivers/scsi/device_handler/scsi_dh.c index ab6c21cd968..3f798171ed6 100644 --- a/drivers/scsi/device_handler/scsi_dh.c +++ b/drivers/scsi/device_handler/scsi_dh.c @@ -33,7 +33,7 @@ static struct scsi_device_handler *get_device_handler(const char *name) spin_lock(&list_lock); list_for_each_entry(tmp, &scsi_dh_list, list) { - if (!strcmp(tmp->name, name)) { + if (!strncmp(tmp->name, name, strlen(tmp->name))) { found = tmp; break; } @@ -42,50 +42,172 @@ static struct scsi_device_handler *get_device_handler(const char *name) return found; } -static int scsi_dh_notifier_add(struct device *dev, void *data) +static int device_handler_match(struct scsi_device_handler *tmp, + struct scsi_device *sdev) { - struct scsi_device_handler *scsi_dh = data; + int i; + + for(i = 0; tmp->devlist[i].vendor; i++) { + if (!strncmp(sdev->vendor, tmp->devlist[i].vendor, + strlen(tmp->devlist[i].vendor)) && + !strncmp(sdev->model, tmp->devlist[i].model, + strlen(tmp->devlist[i].model))) { + return 1; + } + } - scsi_dh->nb.notifier_call(&scsi_dh->nb, BUS_NOTIFY_ADD_DEVICE, dev); return 0; } /* - * scsi_register_device_handler - register a device handler personality - * module. - * @scsi_dh - device handler to be registered. + * scsi_dh_handler_attach - Attach a device handler to a device + * @sdev - SCSI device the device handler should attach to + * @scsi_dh - The device handler to attach + */ +static int scsi_dh_handler_attach(struct scsi_device *sdev, + struct scsi_device_handler *scsi_dh) +{ + int err = 0; + + if (sdev->scsi_dh_data) { + if (sdev->scsi_dh_data->scsi_dh != scsi_dh) + err = -EBUSY; + } else if (scsi_dh->attach) + err = scsi_dh->attach(sdev); + + return err; +} + +/* + * scsi_dh_handler_detach - Detach a device handler from a device + * @sdev - SCSI device the device handler should be detached from + * @scsi_dh - Device handler to be detached * - * Returns 0 on success, -EBUSY if handler already registered. + * Detach from a device handler. If a device handler is specified, + * only detach if the currently attached handler is equal to it. */ -int scsi_register_device_handler(struct scsi_device_handler *scsi_dh) +static void scsi_dh_handler_detach(struct scsi_device *sdev, + struct scsi_device_handler *scsi_dh) { - int ret = -EBUSY; - struct scsi_device_handler *tmp; + if (!sdev->scsi_dh_data) + return; - tmp = get_device_handler(scsi_dh->name); - if (tmp) - goto done; + if (scsi_dh && scsi_dh != sdev->scsi_dh_data->scsi_dh) + return; - ret = bus_register_notifier(&scsi_bus_type, &scsi_dh->nb); + if (!scsi_dh) + scsi_dh = sdev->scsi_dh_data->scsi_dh; + + if (scsi_dh && scsi_dh->detach) + scsi_dh->detach(sdev); +} + +/* + * scsi_dh_notifier - notifier chain callback + */ +static int scsi_dh_notifier(struct notifier_block *nb, + unsigned long action, void *data) +{ + struct device *dev = data; + struct scsi_device *sdev; + int err = 0; + struct scsi_device_handler *tmp, *devinfo = NULL; + + if (!scsi_is_sdev_device(dev)) + return 0; + + sdev = to_scsi_device(dev); - bus_for_each_dev(&scsi_bus_type, NULL, scsi_dh, scsi_dh_notifier_add); spin_lock(&list_lock); - list_add(&scsi_dh->list, &scsi_dh_list); + list_for_each_entry(tmp, &scsi_dh_list, list) { + if (device_handler_match(tmp, sdev)) { + devinfo = tmp; + break; + } + } spin_unlock(&list_lock); -done: - return ret; + if (!devinfo) + goto out; + + if (action == BUS_NOTIFY_ADD_DEVICE) { + err = scsi_dh_handler_attach(sdev, devinfo); + } else if (action == BUS_NOTIFY_DEL_DEVICE) { + scsi_dh_handler_detach(sdev, NULL); + } +out: + return err; } -EXPORT_SYMBOL_GPL(scsi_register_device_handler); +/* + * scsi_dh_notifier_add - Callback for scsi_register_device_handler + */ +static int scsi_dh_notifier_add(struct device *dev, void *data) +{ + struct scsi_device_handler *scsi_dh = data; + struct scsi_device *sdev; + + if (!scsi_is_sdev_device(dev)) + return 0; + + if (!get_device(dev)) + return 0; + + sdev = to_scsi_device(dev); + + if (device_handler_match(scsi_dh, sdev)) + scsi_dh_handler_attach(sdev, scsi_dh); + + put_device(dev); + + return 0; +} + +/* + * scsi_dh_notifier_remove - Callback for scsi_unregister_device_handler + */ static int scsi_dh_notifier_remove(struct device *dev, void *data) { struct scsi_device_handler *scsi_dh = data; + struct scsi_device *sdev; + + if (!scsi_is_sdev_device(dev)) + return 0; + + if (!get_device(dev)) + return 0; + + sdev = to_scsi_device(dev); + + scsi_dh_handler_detach(sdev, scsi_dh); + + put_device(dev); - scsi_dh->nb.notifier_call(&scsi_dh->nb, BUS_NOTIFY_DEL_DEVICE, dev); return 0; } +/* + * scsi_register_device_handler - register a device handler personality + * module. + * @scsi_dh - device handler to be registered. + * + * Returns 0 on success, -EBUSY if handler already registered. + */ +int scsi_register_device_handler(struct scsi_device_handler *scsi_dh) +{ + if (get_device_handler(scsi_dh->name)) + return -EBUSY; + + spin_lock(&list_lock); + list_add(&scsi_dh->list, &scsi_dh_list); + spin_unlock(&list_lock); + bus_for_each_dev(&scsi_bus_type, NULL, scsi_dh, scsi_dh_notifier_add); + printk(KERN_INFO "%s: device handler registered\n", scsi_dh->name); + + return SCSI_DH_OK; +} +EXPORT_SYMBOL_GPL(scsi_register_device_handler); + /* * scsi_unregister_device_handler - register a device handler personality * module. @@ -95,23 +217,18 @@ static int scsi_dh_notifier_remove(struct device *dev, void *data) */ int scsi_unregister_device_handler(struct scsi_device_handler *scsi_dh) { - int ret = -ENODEV; - struct scsi_device_handler *tmp; - - tmp = get_device_handler(scsi_dh->name); - if (!tmp) - goto done; - - ret = bus_unregister_notifier(&scsi_bus_type, &scsi_dh->nb); + if (!get_device_handler(scsi_dh->name)) + return -ENODEV; bus_for_each_dev(&scsi_bus_type, NULL, scsi_dh, - scsi_dh_notifier_remove); + scsi_dh_notifier_remove); + spin_lock(&list_lock); list_del(&scsi_dh->list); spin_unlock(&list_lock); + printk(KERN_INFO "%s: device handler unregistered\n", scsi_dh->name); -done: - return ret; + return SCSI_DH_OK; } EXPORT_SYMBOL_GPL(scsi_unregister_device_handler); @@ -157,6 +274,27 @@ int scsi_dh_handler_exist(const char *name) } EXPORT_SYMBOL_GPL(scsi_dh_handler_exist); +static struct notifier_block scsi_dh_nb = { + .notifier_call = scsi_dh_notifier +}; + +static int __init scsi_dh_init(void) +{ + int r; + + r = bus_register_notifier(&scsi_bus_type, &scsi_dh_nb); + + return r; +} + +static void __exit scsi_dh_exit(void) +{ + bus_unregister_notifier(&scsi_bus_type, &scsi_dh_nb); +} + +module_init(scsi_dh_init); +module_exit(scsi_dh_exit); + MODULE_DESCRIPTION("SCSI device handler"); MODULE_AUTHOR("Chandra Seetharaman "); MODULE_LICENSE("GPL"); -- cgit v1.2.3 From 4c05ae52fcb0e27a2ee4a16d1f31f8c547fd4886 Mon Sep 17 00:00:00 2001 From: Hannes Reinecke Date: Thu, 17 Jul 2008 16:52:57 -0700 Subject: [SCSI] scsi_dh: Add 'dh_state' sysfs attribute Implement a 'dh_state' sdev attribute for dynamic device handler manipulation. A read on the attribute will return the name of the currently attached device handler or 'detached' if no handler is attached. The attribute allows the following strings to be written: - The name of the device handler to be attached if the state is 'detached'. - 'activate' to trigger path activation if a device handler is attached. - 'detach' to detach the currently attached device handler. Signed-off-by: Hannes Reinecke Signed-off-by: Chandra Seetharaman Signed-off-by: James Bottomley --- drivers/scsi/device_handler/scsi_dh.c | 103 +++++++++++++++++++++++++++++++++- 1 file changed, 102 insertions(+), 1 deletion(-) (limited to 'drivers/scsi/device_handler/scsi_dh.c') diff --git a/drivers/scsi/device_handler/scsi_dh.c b/drivers/scsi/device_handler/scsi_dh.c index 3f798171ed6..e90df9dd3e6 100644 --- a/drivers/scsi/device_handler/scsi_dh.c +++ b/drivers/scsi/device_handler/scsi_dh.c @@ -84,7 +84,7 @@ static int scsi_dh_handler_attach(struct scsi_device *sdev, * @scsi_dh - Device handler to be detached * * Detach from a device handler. If a device handler is specified, - * only detach if the currently attached handler is equal to it. + * only detach if the currently attached handler matches @scsi_dh. */ static void scsi_dh_handler_detach(struct scsi_device *sdev, struct scsi_device_handler *scsi_dh) @@ -102,6 +102,98 @@ static void scsi_dh_handler_detach(struct scsi_device *sdev, scsi_dh->detach(sdev); } +/* + * Functions for sysfs attribute 'dh_state' + */ +static ssize_t +store_dh_state(struct device *dev, struct device_attribute *attr, + const char *buf, size_t count) +{ + struct scsi_device *sdev = to_scsi_device(dev); + struct scsi_device_handler *scsi_dh; + int err = -EINVAL; + + if (!sdev->scsi_dh_data) { + /* + * Attach to a device handler + */ + if (!(scsi_dh = get_device_handler(buf))) + return err; + err = scsi_dh_handler_attach(sdev, scsi_dh); + } else { + scsi_dh = sdev->scsi_dh_data->scsi_dh; + if (!strncmp(buf, "detach", 6)) { + /* + * Detach from a device handler + */ + scsi_dh_handler_detach(sdev, scsi_dh); + err = 0; + } else if (!strncmp(buf, "activate", 8)) { + /* + * Activate a device handler + */ + if (scsi_dh->activate) + err = scsi_dh->activate(sdev); + else + err = 0; + } + } + + return err<0?err:count; +} + +static ssize_t +show_dh_state(struct device *dev, struct device_attribute *attr, char *buf) +{ + struct scsi_device *sdev = to_scsi_device(dev); + + if (!sdev->scsi_dh_data) + return snprintf(buf, 20, "detached\n"); + + return snprintf(buf, 20, "%s\n", sdev->scsi_dh_data->scsi_dh->name); +} + +static struct device_attribute scsi_dh_state_attr = + __ATTR(dh_state, S_IRUGO | S_IWUSR, show_dh_state, + store_dh_state); + +/* + * scsi_dh_sysfs_attr_add - Callback for scsi_init_dh + */ +static int scsi_dh_sysfs_attr_add(struct device *dev, void *data) +{ + struct scsi_device *sdev; + int err; + + if (!scsi_is_sdev_device(dev)) + return 0; + + sdev = to_scsi_device(dev); + + err = device_create_file(&sdev->sdev_gendev, + &scsi_dh_state_attr); + + return 0; +} + +/* + * scsi_dh_sysfs_attr_remove - Callback for scsi_exit_dh + */ +static int scsi_dh_sysfs_attr_remove(struct device *dev, void *data) +{ + struct scsi_device *sdev; + + if (!scsi_is_sdev_device(dev)) + return 0; + + sdev = to_scsi_device(dev); + + device_remove_file(&sdev->sdev_gendev, + &scsi_dh_state_attr); + + return 0; +} + /* * scsi_dh_notifier - notifier chain callback */ @@ -132,7 +224,10 @@ static int scsi_dh_notifier(struct notifier_block *nb, if (action == BUS_NOTIFY_ADD_DEVICE) { err = scsi_dh_handler_attach(sdev, devinfo); + if (!err) + err = device_create_file(dev, &scsi_dh_state_attr); } else if (action == BUS_NOTIFY_DEL_DEVICE) { + device_remove_file(dev, &scsi_dh_state_attr); scsi_dh_handler_detach(sdev, NULL); } out: @@ -284,11 +379,17 @@ static int __init scsi_dh_init(void) r = bus_register_notifier(&scsi_bus_type, &scsi_dh_nb); + if (!r) + bus_for_each_dev(&scsi_bus_type, NULL, NULL, + scsi_dh_sysfs_attr_add); + return r; } static void __exit scsi_dh_exit(void) { + bus_for_each_dev(&scsi_bus_type, NULL, NULL, + scsi_dh_sysfs_attr_remove); bus_unregister_notifier(&scsi_bus_type, &scsi_dh_nb); } -- cgit v1.2.3 From ae11b1b36da726a8a93409b896704edc6b4f3402 Mon Sep 17 00:00:00 2001 From: Hannes Reinecke Date: Thu, 17 Jul 2008 17:49:02 -0700 Subject: [SCSI] scsi_dh: attach to hardware handler from dm-mpath multipath keeps a separate device table which may be more current than the built-in one. So we should make sure to always call ->attach whenever a multipath map with hardware handler is instantiated. And we should call ->detach on removal, too. [sekharan: update as per comments from agk] Signed-off-by: Hannes Reinecke Signed-off-by: Chandra Seetharaman Signed-off-by: James Bottomley --- drivers/scsi/device_handler/scsi_dh.c | 64 +++++++++++++++++++++++++++++++++++ 1 file changed, 64 insertions(+) (limited to 'drivers/scsi/device_handler/scsi_dh.c') diff --git a/drivers/scsi/device_handler/scsi_dh.c b/drivers/scsi/device_handler/scsi_dh.c index e90df9dd3e6..a9159681ff2 100644 --- a/drivers/scsi/device_handler/scsi_dh.c +++ b/drivers/scsi/device_handler/scsi_dh.c @@ -369,6 +369,70 @@ int scsi_dh_handler_exist(const char *name) } EXPORT_SYMBOL_GPL(scsi_dh_handler_exist); +/* + * scsi_dh_handler_attach - Attach device handler + * @sdev - sdev the handler should be attached to + * @name - name of the handler to attach + */ +int scsi_dh_attach(struct request_queue *q, const char *name) +{ + unsigned long flags; + struct scsi_device *sdev; + struct scsi_device_handler *scsi_dh; + int err = 0; + + scsi_dh = get_device_handler(name); + if (!scsi_dh) + return -EINVAL; + + spin_lock_irqsave(q->queue_lock, flags); + sdev = q->queuedata; + if (!sdev || !get_device(&sdev->sdev_gendev)) + err = -ENODEV; + spin_unlock_irqrestore(q->queue_lock, flags); + + if (!err) { + err = scsi_dh_handler_attach(sdev, scsi_dh); + + put_device(&sdev->sdev_gendev); + } + return err; +} +EXPORT_SYMBOL_GPL(scsi_dh_attach); + +/* + * scsi_dh_handler_detach - Detach device handler + * @sdev - sdev the handler should be detached from + * + * This function will detach the device handler only + * if the sdev is not part of the internal list, ie + * if it has been attached manually. + */ +void scsi_dh_detach(struct request_queue *q) +{ + unsigned long flags; + struct scsi_device *sdev; + struct scsi_device_handler *scsi_dh = NULL; + + spin_lock_irqsave(q->queue_lock, flags); + sdev = q->queuedata; + if (!sdev || !get_device(&sdev->sdev_gendev)) + sdev = NULL; + spin_unlock_irqrestore(q->queue_lock, flags); + + if (!sdev) + return; + + if (sdev->scsi_dh_data) { + /* if sdev is not on internal list, detach */ + scsi_dh = sdev->scsi_dh_data->scsi_dh; + if (!device_handler_match(scsi_dh, sdev)) + scsi_dh_handler_detach(sdev, scsi_dh); + } + put_device(&sdev->sdev_gendev); +} +EXPORT_SYMBOL_GPL(scsi_dh_detach); + static struct notifier_block scsi_dh_nb = { .notifier_call = scsi_dh_notifier }; -- cgit v1.2.3 From 7c32c7a2d36c52d2b9ed040a9171364020ecc6a2 Mon Sep 17 00:00:00 2001 From: Hannes Reinecke Date: Thu, 17 Jul 2008 16:53:33 -0700 Subject: [SCSI] scsi_dh: create lookup cache Create a cache of devices that are seen in a system. This will avoid the unnecessary traversal of the device list in the scsi_dh when there are multiple luns of a same type. Signed-off-by: Chandra Seetharaman Signed-off-by: Hannes Reinecke Signed-off-by: James Bottomley --- drivers/scsi/device_handler/scsi_dh.c | 129 +++++++++++++++++++++++++++------- 1 file changed, 105 insertions(+), 24 deletions(-) (limited to 'drivers/scsi/device_handler/scsi_dh.c') diff --git a/drivers/scsi/device_handler/scsi_dh.c b/drivers/scsi/device_handler/scsi_dh.c index a9159681ff2..a518f2eff19 100644 --- a/drivers/scsi/device_handler/scsi_dh.c +++ b/drivers/scsi/device_handler/scsi_dh.c @@ -24,8 +24,16 @@ #include #include "../scsi_priv.h" +struct scsi_dh_devinfo_list { + struct list_head node; + char vendor[9]; + char model[17]; + struct scsi_device_handler *handler; +}; + static DEFINE_SPINLOCK(list_lock); static LIST_HEAD(scsi_dh_list); +static LIST_HEAD(scsi_dh_dev_list); static struct scsi_device_handler *get_device_handler(const char *name) { @@ -42,21 +50,94 @@ static struct scsi_device_handler *get_device_handler(const char *name) return found; } -static int device_handler_match(struct scsi_device_handler *tmp, - struct scsi_device *sdev) + +static struct scsi_device_handler * +scsi_dh_cache_lookup(struct scsi_device *sdev) { - int i; - - for(i = 0; tmp->devlist[i].vendor; i++) { - if (!strncmp(sdev->vendor, tmp->devlist[i].vendor, - strlen(tmp->devlist[i].vendor)) && - !strncmp(sdev->model, tmp->devlist[i].model, - strlen(tmp->devlist[i].model))) { - return 1; + struct scsi_dh_devinfo_list *tmp; + struct scsi_device_handler *found_dh = NULL; + + spin_lock(&list_lock); + list_for_each_entry(tmp, &scsi_dh_dev_list, node) { + if (!strncmp(sdev->vendor, tmp->vendor, strlen(tmp->vendor)) && + !strncmp(sdev->model, tmp->model, strlen(tmp->model))) { + found_dh = tmp->handler; + break; } } + spin_unlock(&list_lock); - return 0; + return found_dh; +} + +static int scsi_dh_handler_lookup(struct scsi_device_handler *scsi_dh, + struct scsi_device *sdev) +{ + int i, found = 0; + + for(i = 0; scsi_dh->devlist[i].vendor; i++) { + if (!strncmp(sdev->vendor, scsi_dh->devlist[i].vendor, + strlen(scsi_dh->devlist[i].vendor)) && + !strncmp(sdev->model, scsi_dh->devlist[i].model, + strlen(scsi_dh->devlist[i].model))) { + found = 1; + break; + } + } + return found; +} + +/* + * device_handler_match - Attach a device handler to a device + * @scsi_dh - The device handler to match against or NULL + * @sdev - SCSI device to be tested against @scsi_dh + * + * Tests @sdev against the device handler @scsi_dh or against + * all registered device_handler if @scsi_dh == NULL. + * Returns the found device handler or NULL if not found. + */ +static struct scsi_device_handler * +device_handler_match(struct scsi_device_handler *scsi_dh, + struct scsi_device *sdev) +{ + struct scsi_device_handler *found_dh = NULL; + struct scsi_dh_devinfo_list *tmp; + + found_dh = scsi_dh_cache_lookup(sdev); + if (found_dh) + return found_dh; + + if (scsi_dh) { + if (scsi_dh_handler_lookup(scsi_dh, sdev)) + found_dh = scsi_dh; + } else { + struct scsi_device_handler *tmp_dh; + + spin_lock(&list_lock); + list_for_each_entry(tmp_dh, &scsi_dh_list, list) { + if (scsi_dh_handler_lookup(tmp_dh, sdev)) + found_dh = tmp_dh; + } + spin_unlock(&list_lock); + } + + if (found_dh) { /* If device is found, add it to the cache */ + tmp = kmalloc(sizeof(*tmp), GFP_KERNEL); + if (tmp) { + strncpy(tmp->vendor, sdev->vendor, 8); + strncpy(tmp->model, sdev->model, 16); + tmp->vendor[8] = '\0'; + tmp->model[16] = '\0'; + tmp->handler = found_dh; + spin_lock(&list_lock); + list_add(&tmp->node, &scsi_dh_dev_list); + spin_unlock(&list_lock); + } else { + found_dh = NULL; + } + } + + return found_dh; } /* @@ -203,26 +284,18 @@ static int scsi_dh_notifier(struct notifier_block *nb, struct device *dev = data; struct scsi_device *sdev; int err = 0; - struct scsi_device_handler *tmp, *devinfo = NULL; + struct scsi_device_handler *devinfo = NULL; if (!scsi_is_sdev_device(dev)) return 0; sdev = to_scsi_device(dev); - spin_lock(&list_lock); - list_for_each_entry(tmp, &scsi_dh_list, list) { - if (device_handler_match(tmp, sdev)) { - devinfo = tmp; - break; - } - } - spin_unlock(&list_lock); - - if (!devinfo) - goto out; - if (action == BUS_NOTIFY_ADD_DEVICE) { + devinfo = device_handler_match(NULL, sdev); + if (!devinfo) + goto out; + err = scsi_dh_handler_attach(sdev, devinfo); if (!err) err = device_create_file(dev, &scsi_dh_state_attr); @@ -312,6 +385,8 @@ EXPORT_SYMBOL_GPL(scsi_register_device_handler); */ int scsi_unregister_device_handler(struct scsi_device_handler *scsi_dh) { + struct scsi_dh_devinfo_list *tmp, *pos; + if (!get_device_handler(scsi_dh->name)) return -ENODEV; @@ -320,6 +395,12 @@ int scsi_unregister_device_handler(struct scsi_device_handler *scsi_dh) spin_lock(&list_lock); list_del(&scsi_dh->list); + list_for_each_entry_safe(pos, tmp, &scsi_dh_dev_list, node) { + if (pos->handler == scsi_dh) { + list_del(&pos->node); + kfree(pos); + } + } spin_unlock(&list_lock); printk(KERN_INFO "%s: device handler unregistered\n", scsi_dh->name); -- cgit v1.2.3