Date: Fri, 3 Oct 2008 11:19:09 -0400 From: Jay Fenlason Subject: firewire: add a client_list_lock This adds a client_list_lock, which only protects the device's client_list, so that future versions of the driver can call code that takes the card->lock while holding the client_list_lock. Adding this lock is much simpler than adding __ versions of all the functions that the future version may need. The one ordering issue is to make sure code never takes the client_list_lock with card->lock held. Since client_list_lock is only used in three places, that isn't hard. Signed-off-by: Jay Fenlason Update fill_bus_reset_event() accordingly. Include linux/spinlock.h. Signed-off-by: Stefan Richter --- drivers/firewire/fw-cdev.c | 28 +++++++++++++--------------- drivers/firewire/fw-device.c | 2 ++ drivers/firewire/fw-device.h | 3 +++ 3 files changed, 18 insertions(+), 15 deletions(-) Index: linux/drivers/firewire/fw-cdev.c =================================================================== --- linux.orig/drivers/firewire/fw-cdev.c +++ linux/drivers/firewire/fw-cdev.c @@ -27,6 +27,7 @@ #include #include #include +#include #include #include #include @@ -132,9 +133,9 @@ static int fw_device_op_open(struct inod file->private_data = client; - spin_lock_irqsave(&device->card->lock, flags); + spin_lock_irqsave(&device->client_list_lock, flags); list_add_tail(&client->link, &device->client_list); - spin_unlock_irqrestore(&device->card->lock, flags); + spin_unlock_irqrestore(&device->client_list_lock, flags); return 0; } @@ -205,12 +206,14 @@ fw_device_op_read(struct file *file, return dequeue_event(client, buffer, count); } -/* caller must hold card->lock so that node pointers can be dereferenced here */ static void fill_bus_reset_event(struct fw_cdev_event_bus_reset *event, struct client *client) { struct fw_card *card = client->device->card; + unsigned long flags; + + spin_lock_irqsave(&card->lock, flags); event->closure = client->bus_reset_closure; event->type = FW_CDEV_EVENT_BUS_RESET; @@ -220,22 +223,23 @@ fill_bus_reset_event(struct fw_cdev_even event->bm_node_id = 0; /* FIXME: We don't track the BM. */ event->irm_node_id = card->irm_node->node_id; event->root_node_id = card->root_node->node_id; + + spin_unlock_irqrestore(&card->lock, flags); } static void for_each_client(struct fw_device *device, void (*callback)(struct client *client)) { - struct fw_card *card = device->card; struct client *c; unsigned long flags; - spin_lock_irqsave(&card->lock, flags); + spin_lock_irqsave(&device->client_list_lock, flags); list_for_each_entry(c, &device->client_list, link) callback(c); - spin_unlock_irqrestore(&card->lock, flags); + spin_unlock_irqrestore(&device->client_list_lock, flags); } static void @@ -274,11 +278,11 @@ static int ioctl_get_info(struct client { struct fw_cdev_get_info *get_info = buffer; struct fw_cdev_event_bus_reset bus_reset; - struct fw_card *card = client->device->card; unsigned long ret = 0; client->version = get_info->version; get_info->version = FW_CDEV_VERSION; + get_info->card = client->device->card->index; down_read(&fw_device_rwsem); @@ -300,18 +304,12 @@ static int ioctl_get_info(struct client client->bus_reset_closure = get_info->bus_reset_closure; if (get_info->bus_reset != 0) { void __user *uptr = u64_to_uptr(get_info->bus_reset); - unsigned long flags; - spin_lock_irqsave(&card->lock, flags); fill_bus_reset_event(&bus_reset, client); - spin_unlock_irqrestore(&card->lock, flags); - if (copy_to_user(uptr, &bus_reset, sizeof(bus_reset))) return -EFAULT; } - get_info->card = card->index; - return 0; } @@ -1009,9 +1007,9 @@ static int fw_device_op_release(struct i list_for_each_entry_safe(e, next_e, &client->event_list, link) kfree(e); - spin_lock_irqsave(&client->device->card->lock, flags); + spin_lock_irqsave(&client->device->client_list_lock, flags); list_del(&client->link); - spin_unlock_irqrestore(&client->device->card->lock, flags); + spin_unlock_irqrestore(&client->device->client_list_lock, flags); fw_device_put(client->device); kfree(client); Index: linux/drivers/firewire/fw-device.c =================================================================== --- linux.orig/drivers/firewire/fw-device.c +++ linux/drivers/firewire/fw-device.c @@ -28,6 +28,7 @@ #include #include #include +#include #include #include #include "fw-transaction.h" @@ -925,6 +926,7 @@ void fw_node_event(struct fw_card *card, device->node = fw_node_get(node); device->node_id = node->node_id; device->generation = card->generation; + spin_lock_init(&device->client_list_lock); INIT_LIST_HEAD(&device->client_list); /* Index: linux/drivers/firewire/fw-device.h =================================================================== --- linux.orig/drivers/firewire/fw-device.h +++ linux/drivers/firewire/fw-device.h @@ -22,6 +22,7 @@ #include #include #include +#include #include enum fw_device_state { @@ -62,6 +63,8 @@ struct fw_device { bool cmc; struct fw_card *card; struct device device; + /* to prevent deadlocks, never take this lock with card->lock held */ + spinlock_t client_list_lock; struct list_head client_list; u32 *config_rom; size_t config_rom_length;