diff --git a/drivers/infiniband/core/device.c b/drivers/infiniband/core/device.c index 5096593b99e9..3325be4f91a5 100644 --- a/drivers/infiniband/core/device.c +++ b/drivers/infiniband/core/device.c @@ -37,7 +37,6 @@ #include #include #include -#include #include #include #include @@ -56,6 +55,29 @@ struct workqueue_struct *ib_comp_unbound_wq; struct workqueue_struct *ib_wq; EXPORT_SYMBOL_GPL(ib_wq); +/* + * Each of the three rwsem locks (devices, clients, client_data) protects the + * xarray of the same name. Specifically it allows the caller to assert that + * the MARK will/will not be changing under the lock, and for devices and + * clients, that the value in the xarray is still a valid pointer. Change of + * the MARK is linked to the object state, so holding the lock and testing the + * MARK also asserts that the contained object is in a certain state. + * + * This is used to build a two stage register/unregister flow where objects + * can continue to be in the xarray even though they are still in progress to + * register/unregister. + * + * The xarray itself provides additional locking, and restartable iteration, + * which is also relied on. + * + * Locks should not be nested, with the exception of client_data, which is + * allowed to nest under the read side of the other two locks. + * + * The devices_rwsem also protects the device name list, any change or + * assignment of device name must also hold the write side to guarantee unique + * names. + */ + /* * devices contains devices that have had their names assigned. The * devices may not be registered. Users that care about the registration @@ -64,17 +86,13 @@ EXPORT_SYMBOL_GPL(ib_wq); * */ static DEFINE_XARRAY_FLAGS(devices, XA_FLAGS_ALLOC); - -/* - * Note that if the *rwsem is held and the *_REGISTERED mark is seen then the - * object is guaranteed to be and remain registered for the duration of the - * lock. - */ +static DECLARE_RWSEM(devices_rwsem); #define DEVICE_REGISTERED XA_MARK_1 static LIST_HEAD(client_list); #define CLIENT_REGISTERED XA_MARK_1 static DEFINE_XARRAY_FLAGS(clients, XA_FLAGS_ALLOC); +static DECLARE_RWSEM(clients_rwsem); /* * If client_data is registered then the corresponding client must also still @@ -115,20 +133,6 @@ static void *xan_find_marked(struct xarray *xa, unsigned long *indexp, !xa_is_err(entry); \ (index)++, entry = xan_find_marked(xa, &(index), filter)) -/* - * device_mutex and lists_rwsem protect access to both devices and - * clients. device_mutex protects writer access by device and client - * registration / de-registration. lists_rwsem protects reader access to - * these lists. Iterators of these lists must lock it for read, while updates - * to the lists must be done with a write lock. A special case is when the - * device_mutex is locked. In this case locking the lists for read access is - * not necessary as the device_mutex implies it. - * - * lists_rwsem also protects access to the client data list. - */ -static DEFINE_MUTEX(device_mutex); -static DECLARE_RWSEM(lists_rwsem); - static int ib_security_change(struct notifier_block *nb, unsigned long event, void *lsm_data); static void ib_policy_change_task(struct work_struct *work); @@ -185,13 +189,13 @@ struct ib_device *ib_device_get_by_index(u32 index) { struct ib_device *device; - down_read(&lists_rwsem); + down_read(&devices_rwsem); device = xa_load(&devices, index); if (device) { if (!ib_device_try_get(device)) device = NULL; } - up_read(&lists_rwsem); + up_read(&devices_rwsem); return device; } @@ -225,7 +229,7 @@ int ib_device_rename(struct ib_device *ibdev, const char *name) { int ret; - mutex_lock(&device_mutex); + down_write(&devices_rwsem); if (!strcmp(name, dev_name(&ibdev->dev))) { ret = 0; goto out; @@ -241,7 +245,7 @@ int ib_device_rename(struct ib_device *ibdev, const char *name) goto out; strlcpy(ibdev->name, name, IB_DEVICE_NAME_MAX); out: - mutex_unlock(&device_mutex); + up_write(&devices_rwsem); return ret; } @@ -253,6 +257,7 @@ static int alloc_name(struct ib_device *ibdev, const char *name) int rc; int i; + lockdep_assert_held_exclusive(&devices_rwsem); ida_init(&inuse); xa_for_each (&devices, index, device) { char buf[IB_DEVICE_NAME_MAX]; @@ -345,6 +350,7 @@ struct ib_device *_ib_alloc_device(size_t size) * destroyed if the user stores NULL in the client data. */ xa_init_flags(&device->client_data, XA_FLAGS_ALLOC); + init_rwsem(&device->client_data_rwsem); INIT_LIST_HEAD(&device->port_list); init_completion(&device->unreg_completion); @@ -367,22 +373,86 @@ void ib_dealloc_device(struct ib_device *device) } EXPORT_SYMBOL(ib_dealloc_device); -static int add_client_context(struct ib_device *device, struct ib_client *client) +/* + * add_client_context() and remove_client_context() must be safe against + * parallel calls on the same device - registration/unregistration of both the + * device and client can be occurring in parallel. + * + * The routines need to be a fence, any caller must not return until the add + * or remove is fully completed. + */ +static int add_client_context(struct ib_device *device, + struct ib_client *client) { - void *entry; + int ret = 0; if (!device->kverbs_provider && !client->no_kverbs_req) - return -EOPNOTSUPP; + return 0; - down_write(&lists_rwsem); - entry = xa_store(&device->client_data, client->client_id, NULL, - GFP_KERNEL); - if (!xa_is_err(entry)) - xa_set_mark(&device->client_data, client->client_id, - CLIENT_DATA_REGISTERED); - up_write(&lists_rwsem); + down_write(&device->client_data_rwsem); + /* + * Another caller to add_client_context got here first and has already + * completely initialized context. + */ + if (xa_get_mark(&device->client_data, client->client_id, + CLIENT_DATA_REGISTERED)) + goto out; - return xa_err(entry); + ret = xa_err(xa_store(&device->client_data, client->client_id, NULL, + GFP_KERNEL)); + if (ret) + goto out; + downgrade_write(&device->client_data_rwsem); + if (client->add) + client->add(device); + + /* Readers shall not see a client until add has been completed */ + xa_set_mark(&device->client_data, client->client_id, + CLIENT_DATA_REGISTERED); + up_read(&device->client_data_rwsem); + return 0; + +out: + up_write(&device->client_data_rwsem); + return ret; +} + +static void remove_client_context(struct ib_device *device, + unsigned int client_id) +{ + struct ib_client *client; + void *client_data; + + down_write(&device->client_data_rwsem); + if (!xa_get_mark(&device->client_data, client_id, + CLIENT_DATA_REGISTERED)) { + up_write(&device->client_data_rwsem); + return; + } + client_data = xa_load(&device->client_data, client_id); + xa_clear_mark(&device->client_data, client_id, CLIENT_DATA_REGISTERED); + client = xa_load(&clients, client_id); + downgrade_write(&device->client_data_rwsem); + + /* + * Notice we cannot be holding any exclusive locks when calling the + * remove callback as the remove callback can recurse back into any + * public functions in this module and thus try for any locks those + * functions take. + * + * For this reason clients and drivers should not call the + * unregistration functions will holdling any locks. + * + * It tempting to drop the client_data_rwsem too, but this is required + * to ensure that unregister_client does not return until all clients + * are completely unregistered, which is required to avoid module + * unloading races. + */ + if (client->remove) + client->remove(device, client_data); + + xa_erase(&device->client_data, client_id); + up_read(&device->client_data_rwsem); } static int verify_immutable(const struct ib_device *dev, u8 port) @@ -461,7 +531,7 @@ static void ib_policy_change_task(struct work_struct *work) struct ib_device *dev; unsigned long index; - down_read(&lists_rwsem); + down_read(&devices_rwsem); xa_for_each_marked (&devices, index, dev, DEVICE_REGISTERED) { int i; @@ -478,7 +548,7 @@ static void ib_policy_change_task(struct work_struct *work) ib_security_cache_change(dev, i, sp); } } - up_read(&lists_rwsem); + up_read(&devices_rwsem); } static int ib_security_change(struct notifier_block *nb, unsigned long event, @@ -501,6 +571,7 @@ static int assign_name(struct ib_device *device, const char *name) static u32 last_id; int ret; + down_write(&devices_rwsem); /* Assign a unique name to the device */ if (strchr(name, '%')) ret = alloc_name(device, name); @@ -528,13 +599,17 @@ static int assign_name(struct ib_device *device, const char *name) last_id = device->index + 1; ret = 0; + out: + up_write(&devices_rwsem); return ret; } static void release_name(struct ib_device *device) { + down_write(&devices_rwsem); xa_erase(&devices, device->index); + up_write(&devices_rwsem); } static void setup_dma_device(struct ib_device *device) @@ -572,11 +647,18 @@ static void setup_dma_device(struct ib_device *device) } } +/* + * setup_device() allocates memory and sets up data that requires calling the + * device ops, this is the only reason these actions are not done during + * ib_alloc_device. It is undone by ib_dealloc_device(). + */ static int setup_device(struct ib_device *device) { struct ib_udata uhw = {.outlen = 0, .inlen = 0}; int ret; + setup_dma_device(device); + ret = ib_device_check_mandatory(device); if (ret) return ret; @@ -605,6 +687,54 @@ static int setup_device(struct ib_device *device) return 0; } +static void disable_device(struct ib_device *device) +{ + struct ib_client *client; + + WARN_ON(!refcount_read(&device->refcount)); + + down_write(&devices_rwsem); + xa_clear_mark(&devices, device->index, DEVICE_REGISTERED); + up_write(&devices_rwsem); + + down_read(&clients_rwsem); + list_for_each_entry_reverse(client, &client_list, list) + remove_client_context(device, client->client_id); + up_read(&clients_rwsem); + + /* Pairs with refcount_set in enable_device */ + ib_device_put(device); + wait_for_completion(&device->unreg_completion); +} + +/* + * An enabled device is visible to all clients and to all the public facing + * APIs that return a device pointer. + */ +static int enable_device(struct ib_device *device) +{ + struct ib_client *client; + unsigned long index; + int ret; + + refcount_set(&device->refcount, 1); + down_write(&devices_rwsem); + xa_set_mark(&devices, device->index, DEVICE_REGISTERED); + up_write(&devices_rwsem); + + down_read(&clients_rwsem); + xa_for_each_marked (&clients, index, client, CLIENT_REGISTERED) { + ret = add_client_context(device, client); + if (ret) { + up_read(&clients_rwsem); + disable_device(device); + return ret; + } + } + up_read(&clients_rwsem); + return 0; +} + /** * ib_register_device - Register an IB device with IB core * @device:Device to register @@ -617,26 +747,20 @@ static int setup_device(struct ib_device *device) int ib_register_device(struct ib_device *device, const char *name) { int ret; - struct ib_client *client; - unsigned long index; - - setup_dma_device(device); - - mutex_lock(&device_mutex); ret = assign_name(device, name); if (ret) - goto out; + return ret; ret = setup_device(device); if (ret) - goto out_name; + goto out; ret = ib_cache_setup_one(device); if (ret) { dev_warn(&device->dev, "Couldn't set up InfiniBand P_Key/GID cache\n"); - goto out_name; + goto out; } ib_device_register_rdmacg(device); @@ -648,25 +772,19 @@ int ib_register_device(struct ib_device *device, const char *name) goto cg_cleanup; } - refcount_set(&device->refcount, 1); + ret = enable_device(device); + if (ret) + goto sysfs_cleanup; - xa_for_each_marked (&clients, index, client, CLIENT_REGISTERED) - if (!add_client_context(device, client) && client->add) - client->add(device); - - down_write(&lists_rwsem); - xa_set_mark(&devices, device->index, DEVICE_REGISTERED); - up_write(&lists_rwsem); - mutex_unlock(&device_mutex); return 0; +sysfs_cleanup: + ib_device_unregister_sysfs(device); cg_cleanup: ib_device_unregister_rdmacg(device); ib_cache_cleanup_one(device); -out_name: - release_name(device); out: - mutex_unlock(&device_mutex); + release_name(device); return ret; } EXPORT_SYMBOL(ib_register_device); @@ -679,45 +797,11 @@ EXPORT_SYMBOL(ib_register_device); */ void ib_unregister_device(struct ib_device *device) { - struct ib_client *client; - unsigned long index; - - /* - * Wait for all netlink command callers to finish working on the - * device. - */ - ib_device_put(device); - wait_for_completion(&device->unreg_completion); - - mutex_lock(&device_mutex); - - down_write(&lists_rwsem); - xa_clear_mark(&devices, device->index, DEVICE_REGISTERED); - xa_for_each (&clients, index, client) - xa_clear_mark(&device->client_data, index, - CLIENT_DATA_REGISTERED); - downgrade_write(&lists_rwsem); - - list_for_each_entry_reverse(client, &client_list, list) - if (xa_get_mark(&device->client_data, client->client_id, - CLIENT_DATA_REGISTERED) && - client->remove) - client->remove(device, xa_load(&device->client_data, - client->client_id)); - up_read(&lists_rwsem); - + disable_device(device); ib_device_unregister_sysfs(device); ib_device_unregister_rdmacg(device); - - release_name(device); - - mutex_unlock(&device_mutex); - ib_cache_cleanup_one(device); - - down_write(&lists_rwsem); - xa_destroy(&device->client_data); - up_write(&lists_rwsem); + release_name(device); } EXPORT_SYMBOL(ib_unregister_device); @@ -725,6 +809,7 @@ static int assign_client_id(struct ib_client *client) { int ret; + down_write(&clients_rwsem); /* * The add/remove callbacks must be called in FIFO/LIFO order. To * achieve this we assign client_ids so they are sorted in @@ -743,7 +828,11 @@ static int assign_client_id(struct ib_client *client) if (ret) goto out; + xa_set_mark(&clients, client->client_id, CLIENT_REGISTERED); + list_add_tail(&client->list, &client_list); + out: + up_write(&clients_rwsem); return ret; } @@ -766,23 +855,20 @@ int ib_register_client(struct ib_client *client) unsigned long index; int ret; - mutex_lock(&device_mutex); ret = assign_client_id(client); - if (ret) { - mutex_unlock(&device_mutex); + if (ret) return ret; + + down_read(&devices_rwsem); + xa_for_each_marked (&devices, index, device, DEVICE_REGISTERED) { + ret = add_client_context(device, client); + if (ret) { + up_read(&devices_rwsem); + ib_unregister_client(client); + return ret; + } } - - xa_for_each_marked (&devices, index, device, DEVICE_REGISTERED) - if (!add_client_context(device, client) && client->add) - client->add(device); - - down_write(&lists_rwsem); - xa_set_mark(&clients, client->client_id, CLIENT_REGISTERED); - up_write(&lists_rwsem); - - mutex_unlock(&device_mutex); - + up_read(&devices_rwsem); return 0; } EXPORT_SYMBOL(ib_register_client); @@ -794,38 +880,31 @@ EXPORT_SYMBOL(ib_register_client); * Upper level users use ib_unregister_client() to remove their client * registration. When ib_unregister_client() is called, the client * will receive a remove callback for each IB device still registered. + * + * This is a full fence, once it returns no client callbacks will be called, + * or are running in another thread. */ void ib_unregister_client(struct ib_client *client) { struct ib_device *device; unsigned long index; - mutex_lock(&device_mutex); - - down_write(&lists_rwsem); + down_write(&clients_rwsem); xa_clear_mark(&clients, client->client_id, CLIENT_REGISTERED); - up_write(&lists_rwsem); + up_write(&clients_rwsem); + /* + * Every device still known must be serialized to make sure we are + * done with the client callbacks before we return. + */ + down_read(&devices_rwsem); + xa_for_each (&devices, index, device) + remove_client_context(device, client->client_id); + up_read(&devices_rwsem); - xa_for_each_marked (&devices, index, device, DEVICE_REGISTERED) { - down_write(&lists_rwsem); - xa_clear_mark(&device->client_data, client->client_id, - CLIENT_DATA_REGISTERED); - up_write(&lists_rwsem); - - if (client->remove) - client->remove(device, xa_load(&device->client_data, - client->client_id)); - - down_write(&lists_rwsem); - xa_erase(&device->client_data, client->client_id); - up_write(&lists_rwsem); - } - - down_write(&lists_rwsem); + down_write(&clients_rwsem); list_del(&client->list); xa_erase(&clients, client->client_id); - up_write(&lists_rwsem); - mutex_unlock(&device_mutex); + up_write(&clients_rwsem); } EXPORT_SYMBOL(ib_unregister_client); @@ -1010,10 +1089,10 @@ void ib_enum_all_roce_netdevs(roce_netdev_filter filter, struct ib_device *dev; unsigned long index; - down_read(&lists_rwsem); + down_read(&devices_rwsem); xa_for_each_marked (&devices, index, dev, DEVICE_REGISTERED) ib_enum_roce_netdev(dev, filter, filter_cookie, cb, cookie); - up_read(&lists_rwsem); + up_read(&devices_rwsem); } /** @@ -1030,15 +1109,14 @@ int ib_enum_all_devs(nldev_callback nldev_cb, struct sk_buff *skb, unsigned int idx = 0; int ret = 0; - down_read(&lists_rwsem); + down_read(&devices_rwsem); xa_for_each_marked (&devices, index, dev, DEVICE_REGISTERED) { ret = nldev_cb(dev, skb, cb, idx); if (ret) break; idx++; } - - up_read(&lists_rwsem); + up_read(&devices_rwsem); return ret; } @@ -1196,6 +1274,7 @@ EXPORT_SYMBOL(ib_find_pkey); * @gid: A GID that the net_dev uses to communicate. * @addr: Contains the IP address that the request specified as its * destination. + * */ struct net_device *ib_get_net_dev_by_params(struct ib_device *dev, u8 port, @@ -1210,8 +1289,11 @@ struct net_device *ib_get_net_dev_by_params(struct ib_device *dev, if (!rdma_protocol_ib(dev, port)) return NULL; - down_read(&lists_rwsem); - + /* + * Holding the read side guarantees that the client will not become + * unregistered while we are calling get_net_dev_by_params() + */ + down_read(&dev->client_data_rwsem); xan_for_each_marked (&dev->client_data, index, client_data, CLIENT_DATA_REGISTERED) { struct ib_client *client = xa_load(&clients, index); @@ -1224,8 +1306,7 @@ struct net_device *ib_get_net_dev_by_params(struct ib_device *dev, if (net_dev) break; } - - up_read(&lists_rwsem); + up_read(&dev->client_data_rwsem); return net_dev; } diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h index 8558f31ca46f..135fab2c016c 100644 --- a/include/rdma/ib_verbs.h +++ b/include/rdma/ib_verbs.h @@ -2542,6 +2542,7 @@ struct ib_device { struct list_head event_handler_list; spinlock_t event_handler_lock; + struct rw_semaphore client_data_rwsem; struct xarray client_data; struct ib_cache cache;