Date: Wed Oct 13 13:39:46 CEST 2010 From: Stefan Richter Subject: firewire: core: use non-reentrant workqueue with rescuer firewire-core manages the following types of work items: fw_card.br_work: - resets the bus on a card and possibly sends a PHY packet before that - does not sleep for long or not at all - is scheduled via fw_schedule_bus_reset() by - firewire-ohci's pci_probe method - firewire-ohci's set_config_rom method, called by kernelspace protocol drivers and userspace drivers which add/remove Configuration ROM descriptors - userspace drivers which use the bus reset ioctl - itself if the last reset happened less than 2 seconds ago fw_card.bm_work: - performs bus management duties - usually does not (but may in corner cases) sleep for long - is scheduled via fw_schedule_bm_work() by - firewire-ohci's self-ID-complete IRQ handler tasklet - firewire-core's fw_device.work instances whenever the root node device was (successfully or unsuccessfully) discovered, refreshed, or rediscovered - itself in case of resource allocation failures or in order to obey the 125ms bus manager arbitration interval fw_device.work: - performs node probe, update, shutdown, revival, removal; including kernel driver probe, update, shutdown and bus reset notification to userspace drivers - usually sleeps moderately long, in corner cases very long - is scheduled by - firewire-ohci's self-ID-complete IRQ handler tasklet via the core's fw_node_event - firewire-ohci's pci_remove method via core's fw_destroy_nodes/ fw_node_event - itself during retries, e.g. while a node is powering up iso_resource.work: - accesses registers at the Isochronous Resource Manager node - usually does not (but may in corner cases) sleep for long - is scheduled via schedule_iso_resource() by - the owning userspace driver at addition and removal of the resource - firewire-core's fw_device.work instances after bus reset - itself in case of resource allocation if necessary to obey the 1000ms reallocation period after bus reset fw_card.br_work instances should not, and instances of the others must not, be executed in parallel by multiple CPUs -- but were not protected against that. Hence allocate a non-reentrant workqueue for them. fw_device.work may be used in the memory reclaim path in case of SBP-2 device updates. Hence we need a workqueue with rescuer and cannot use system_nrt_wq. Signed-off-by: Stefan Richter Reviewed-by: Tejun Heo --- drivers/firewire/core-card.c | 6 +++--- drivers/firewire/core-cdev.c | 2 +- drivers/firewire/core-device.c | 30 ++++++++++++++++++---------- drivers/firewire/core-transaction.c | 12 ++++++++++- drivers/firewire/core.h | 2 ++ 5 files changed, 36 insertions(+), 16 deletions(-) Index: b/drivers/firewire/core-card.c =================================================================== --- a/drivers/firewire/core-card.c +++ b/drivers/firewire/core-card.c @@ -228,8 +228,8 @@ void fw_schedule_bus_reset(struct fw_car /* Use an arbitrary short delay to combine multiple reset requests. */ fw_card_get(card); - if (!schedule_delayed_work(&card->br_work, - delayed ? DIV_ROUND_UP(HZ, 100) : 0)) + if (!queue_delayed_work(fw_wq, &card->br_work, + delayed ? DIV_ROUND_UP(HZ, 100) : 0)) fw_card_put(card); } EXPORT_SYMBOL(fw_schedule_bus_reset); @@ -241,7 +241,7 @@ static void br_work(struct work_struct * /* Delay for 2s after last reset per IEEE 1394 clause 8.2.1. */ if (card->reset_jiffies != 0 && time_before64(get_jiffies_64(), card->reset_jiffies + 2 * HZ)) { - if (!schedule_delayed_work(&card->br_work, 2 * HZ)) + if (!queue_delayed_work(fw_wq, &card->br_work, 2 * HZ)) fw_card_put(card); return; } Index: b/drivers/firewire/core-cdev.c =================================================================== --- a/drivers/firewire/core-cdev.c +++ b/drivers/firewire/core-cdev.c @@ -149,7 +149,7 @@ static void release_iso_resource(struct static void schedule_iso_resource(struct iso_resource *r, unsigned long delay) { client_get(r->client); - if (!schedule_delayed_work(&r->work, delay)) + if (!queue_delayed_work(fw_wq, &r->work, delay)) client_put(r->client); } Index: b/drivers/firewire/core-device.c =================================================================== --- a/drivers/firewire/core-device.c +++ b/drivers/firewire/core-device.c @@ -725,6 +725,14 @@ struct fw_device *fw_device_get_by_devt( return device; } +struct workqueue_struct *fw_wq; + +static void fw_schedule_device_work(struct fw_device *device, + unsigned long delay) +{ + queue_delayed_work(fw_wq, &device->work, delay); +} + /* * These defines control the retry behavior for reading the config * rom. It shouldn't be necessary to tweak these; if the device @@ -750,7 +758,7 @@ static void fw_device_shutdown(struct wo if (time_before64(get_jiffies_64(), device->card->reset_jiffies + SHUTDOWN_DELAY) && !list_empty(&device->card->link)) { - schedule_delayed_work(&device->work, SHUTDOWN_DELAY); + fw_schedule_device_work(device, SHUTDOWN_DELAY); return; } @@ -862,7 +870,7 @@ static int lookup_existing_device(struct fw_notify("rediscovered device %s\n", dev_name(dev)); PREPARE_DELAYED_WORK(&old->work, fw_device_update); - schedule_delayed_work(&old->work, 0); + fw_schedule_device_work(old, 0); if (current_node == card->root_node) fw_schedule_bm_work(card, 0); @@ -953,7 +961,7 @@ static void fw_device_init(struct work_s if (device->config_rom_retries < MAX_RETRIES && atomic_read(&device->state) == FW_DEVICE_INITIALIZING) { device->config_rom_retries++; - schedule_delayed_work(&device->work, RETRY_DELAY); + fw_schedule_device_work(device, RETRY_DELAY); } else { if (device->node->link_on) fw_notify("giving up on config rom for node id %x\n", @@ -1019,7 +1027,7 @@ static void fw_device_init(struct work_s FW_DEVICE_INITIALIZING, FW_DEVICE_RUNNING) == FW_DEVICE_GONE) { PREPARE_DELAYED_WORK(&device->work, fw_device_shutdown); - schedule_delayed_work(&device->work, SHUTDOWN_DELAY); + fw_schedule_device_work(device, SHUTDOWN_DELAY); } else { if (device->config_rom_retries) fw_notify("created device %s: GUID %08x%08x, S%d00, " @@ -1098,7 +1106,7 @@ static void fw_device_refresh(struct wor if (device->config_rom_retries < MAX_RETRIES / 2 && atomic_read(&device->state) == FW_DEVICE_INITIALIZING) { device->config_rom_retries++; - schedule_delayed_work(&device->work, RETRY_DELAY / 2); + fw_schedule_device_work(device, RETRY_DELAY / 2); return; } @@ -1131,7 +1139,7 @@ static void fw_device_refresh(struct wor if (device->config_rom_retries < MAX_RETRIES && atomic_read(&device->state) == FW_DEVICE_INITIALIZING) { device->config_rom_retries++; - schedule_delayed_work(&device->work, RETRY_DELAY); + fw_schedule_device_work(device, RETRY_DELAY); return; } @@ -1158,7 +1166,7 @@ static void fw_device_refresh(struct wor gone: atomic_set(&device->state, FW_DEVICE_GONE); PREPARE_DELAYED_WORK(&device->work, fw_device_shutdown); - schedule_delayed_work(&device->work, SHUTDOWN_DELAY); + fw_schedule_device_work(device, SHUTDOWN_DELAY); out: if (node_id == card->root_node->node_id) fw_schedule_bm_work(card, 0); @@ -1214,7 +1222,7 @@ void fw_node_event(struct fw_card *card, * first config rom scan half a second after bus reset. */ INIT_DELAYED_WORK(&device->work, fw_device_init); - schedule_delayed_work(&device->work, INITIAL_DELAY); + fw_schedule_device_work(device, INITIAL_DELAY); break; case FW_NODE_INITIATED_RESET: @@ -1230,7 +1238,7 @@ void fw_node_event(struct fw_card *card, FW_DEVICE_RUNNING, FW_DEVICE_INITIALIZING) == FW_DEVICE_RUNNING) { PREPARE_DELAYED_WORK(&device->work, fw_device_refresh); - schedule_delayed_work(&device->work, + fw_schedule_device_work(device, device->is_local ? 0 : INITIAL_DELAY); } break; @@ -1245,7 +1253,7 @@ void fw_node_event(struct fw_card *card, device->generation = card->generation; if (atomic_read(&device->state) == FW_DEVICE_RUNNING) { PREPARE_DELAYED_WORK(&device->work, fw_device_update); - schedule_delayed_work(&device->work, 0); + fw_schedule_device_work(device, 0); } break; @@ -1270,7 +1278,7 @@ void fw_node_event(struct fw_card *card, if (atomic_xchg(&device->state, FW_DEVICE_GONE) == FW_DEVICE_RUNNING) { PREPARE_DELAYED_WORK(&device->work, fw_device_shutdown); - schedule_delayed_work(&device->work, + fw_schedule_device_work(device, list_empty(&card->link) ? 0 : SHUTDOWN_DELAY); } break; Index: b/drivers/firewire/core-transaction.c =================================================================== --- a/drivers/firewire/core-transaction.c +++ b/drivers/firewire/core-transaction.c @@ -36,6 +36,7 @@ #include #include #include +#include #include @@ -1213,13 +1214,21 @@ static int __init fw_core_init(void) { int ret; + fw_wq = alloc_workqueue(KBUILD_MODNAME, + WQ_NON_REENTRANT | WQ_MEM_RECLAIM, 0); + if (!fw_wq) + return -ENOMEM; + ret = bus_register(&fw_bus_type); - if (ret < 0) + if (ret < 0) { + destroy_workqueue(fw_wq); return ret; + } fw_cdev_major = register_chrdev(0, "firewire", &fw_device_ops); if (fw_cdev_major < 0) { bus_unregister(&fw_bus_type); + destroy_workqueue(fw_wq); return fw_cdev_major; } @@ -1235,6 +1244,7 @@ static void __exit fw_core_cleanup(void) { unregister_chrdev(fw_cdev_major, "firewire"); bus_unregister(&fw_bus_type); + destroy_workqueue(fw_wq); idr_destroy(&fw_device_idr); } Index: b/drivers/firewire/core.h =================================================================== --- a/drivers/firewire/core.h +++ b/drivers/firewire/core.h @@ -138,6 +138,8 @@ void fw_cdev_handle_phy_packet(struct fw extern struct rw_semaphore fw_device_rwsem; extern struct idr fw_device_idr; extern int fw_cdev_major; +struct workqueue_struct; +extern struct workqueue_struct *fw_wq; struct fw_device *fw_device_get_by_devt(dev_t devt); int fw_device_set_broadcast_channel(struct device *dev, void *gen);