From c30c9b15187e977ab5928f7276e9dfcd8d6f9460 Mon Sep 17 00:00:00 2001 From: David Fries Date: Wed, 15 Oct 2008 22:04:38 -0700 Subject: [PATCH] W1: fix deadlocks and remove w1_control_thread w1_control_thread was removed which would wake up every second and process newly registered family codes and complete some final cleanup for a removed master. Those routines were moved to the threads that were previously requesting those operations. A new function w1_reconnect_slaves takes care of reconnecting existing slave devices when a new family code is registered or removed. The removal case was missing and would cause a deadlock waiting for the family code reference count to decrease, which will now happen. A problem with registering a family code was fixed. A slave device would be unattached if it wasn't yet claimed, then attached at the end of the list, two unclaimed slaves would cause an infinite loop. The struct w1_bus_master.search now takes a pointer to the struct w1_master device to avoid searching for it, which would have caused a lock ordering deadlock with the removal of w1_control_thread. Signed-off-by: David Fries Signed-off-by: Evgeniy Polyakov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/w1/masters/ds1wm.c | 6 +- drivers/w1/w1.c | 146 +++++++++---------------------------- drivers/w1/w1.h | 19 ++++- drivers/w1/w1_family.c | 6 +- drivers/w1/w1_family.h | 1 - drivers/w1/w1_int.c | 12 +++ drivers/w1/w1_io.c | 3 +- 7 files changed, 71 insertions(+), 122 deletions(-) diff --git a/drivers/w1/masters/ds1wm.c b/drivers/w1/masters/ds1wm.c index 10211e493001..ea894bf18113 100644 --- a/drivers/w1/masters/ds1wm.c +++ b/drivers/w1/masters/ds1wm.c @@ -274,8 +274,8 @@ static u8 ds1wm_reset_bus(void *data) return 0; } -static void ds1wm_search(void *data, u8 search_type, - w1_slave_found_callback slave_found) +static void ds1wm_search(void *data, struct w1_master *master_dev, + u8 search_type, w1_slave_found_callback slave_found) { struct ds1wm_data *ds1wm_data = data; int i; @@ -313,7 +313,7 @@ static void ds1wm_search(void *data, u8 search_type, ds1wm_write_register(ds1wm_data, DS1WM_CMD, ~DS1WM_CMD_SRA); ds1wm_reset(ds1wm_data); - slave_found(ds1wm_data, rom_id); + slave_found(master_dev, rom_id); } /* --------------------------------------------------------------------- */ diff --git a/drivers/w1/w1.c b/drivers/w1/w1.c index 7293c9b11f91..25640f681729 100644 --- a/drivers/w1/w1.c +++ b/drivers/w1/w1.c @@ -46,20 +46,16 @@ MODULE_AUTHOR("Evgeniy Polyakov "); MODULE_DESCRIPTION("Driver for 1-wire Dallas network protocol."); static int w1_timeout = 10; -static int w1_control_timeout = 1; int w1_max_slave_count = 10; int w1_max_slave_ttl = 10; module_param_named(timeout, w1_timeout, int, 0); -module_param_named(control_timeout, w1_control_timeout, int, 0); module_param_named(max_slave_count, w1_max_slave_count, int, 0); module_param_named(slave_ttl, w1_max_slave_ttl, int, 0); DEFINE_MUTEX(w1_mlock); LIST_HEAD(w1_masters); -static struct task_struct *w1_control_thread; - static int w1_master_match(struct device *dev, struct device_driver *drv) { return 1; @@ -390,7 +386,7 @@ int w1_create_master_attributes(struct w1_master *master) return sysfs_create_group(&master->dev.kobj, &w1_master_defattr_group); } -static void w1_destroy_master_attributes(struct w1_master *master) +void w1_destroy_master_attributes(struct w1_master *master) { sysfs_remove_group(&master->dev.kobj, &w1_master_defattr_group); } @@ -567,7 +563,7 @@ static int w1_attach_slave_device(struct w1_master *dev, struct w1_reg_num *rn) return 0; } -static void w1_slave_detach(struct w1_slave *sl) +void w1_slave_detach(struct w1_slave *sl) { struct w1_netlink_msg msg; @@ -591,24 +587,6 @@ static void w1_slave_detach(struct w1_slave *sl) kfree(sl); } -static struct w1_master *w1_search_master(void *data) -{ - struct w1_master *dev; - int found = 0; - - mutex_lock(&w1_mlock); - list_for_each_entry(dev, &w1_masters, w1_master_entry) { - if (dev->bus_master->data == data) { - found = 1; - atomic_inc(&dev->refcnt); - break; - } - } - mutex_unlock(&w1_mlock); - - return (found)?dev:NULL; -} - struct w1_master *w1_search_master_id(u32 id) { struct w1_master *dev; @@ -656,34 +634,49 @@ struct w1_slave *w1_search_slave(struct w1_reg_num *id) return (found)?sl:NULL; } -void w1_reconnect_slaves(struct w1_family *f) +void w1_reconnect_slaves(struct w1_family *f, int attach) { + struct w1_slave *sl, *sln; struct w1_master *dev; mutex_lock(&w1_mlock); list_for_each_entry(dev, &w1_masters, w1_master_entry) { - dev_dbg(&dev->dev, "Reconnecting slaves in %s into new family %02x.\n", - dev->name, f->fid); - set_bit(W1_MASTER_NEED_RECONNECT, &dev->flags); + dev_dbg(&dev->dev, "Reconnecting slaves in device %s " + "for family %02x.\n", dev->name, f->fid); + mutex_lock(&dev->mutex); + list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) { + /* If it is a new family, slaves with the default + * family driver and are that family will be + * connected. If the family is going away, devices + * matching that family are reconneced. + */ + if ((attach && sl->family->fid == W1_FAMILY_DEFAULT + && sl->reg_num.family == f->fid) || + (!attach && sl->family->fid == f->fid)) { + struct w1_reg_num rn; + + memcpy(&rn, &sl->reg_num, sizeof(rn)); + w1_slave_detach(sl); + + w1_attach_slave_device(dev, &rn); + } + } + dev_dbg(&dev->dev, "Reconnecting slaves in device %s " + "has been finished.\n", dev->name); + mutex_unlock(&dev->mutex); } mutex_unlock(&w1_mlock); } -static void w1_slave_found(void *data, u64 rn) +static void w1_slave_found(struct w1_master *dev, u64 rn) { int slave_count; struct w1_slave *sl; struct list_head *ent; struct w1_reg_num *tmp; - struct w1_master *dev; u64 rn_le = cpu_to_le64(rn); - dev = w1_search_master(data); - if (!dev) { - printk(KERN_ERR "Failed to find w1 master device for data %p, " - "it is impossible.\n", data); - return; - } + atomic_inc(&dev->refcnt); tmp = (struct w1_reg_num *) &rn; @@ -785,76 +778,11 @@ void w1_search(struct w1_master *dev, u8 search_type, w1_slave_found_callback cb if ( (desc_bit == last_zero) || (last_zero < 0)) last_device = 1; desc_bit = last_zero; - cb(dev->bus_master->data, rn); + cb(dev, rn); } } } -static int w1_control(void *data) -{ - struct w1_slave *sl, *sln; - struct w1_master *dev, *n; - int have_to_wait = 0; - - set_freezable(); - while (!kthread_should_stop() || have_to_wait) { - have_to_wait = 0; - - try_to_freeze(); - msleep_interruptible(w1_control_timeout * 1000); - - list_for_each_entry_safe(dev, n, &w1_masters, w1_master_entry) { - if (!kthread_should_stop() && !dev->flags) - continue; - /* - * Little race: we can create thread but not set the flag. - * Get a chance for external process to set flag up. - */ - if (!dev->initialized) { - have_to_wait = 1; - continue; - } - - if (kthread_should_stop() || test_bit(W1_MASTER_NEED_EXIT, &dev->flags)) { - set_bit(W1_MASTER_NEED_EXIT, &dev->flags); - - mutex_lock(&w1_mlock); - list_del(&dev->w1_master_entry); - mutex_unlock(&w1_mlock); - - mutex_lock(&dev->mutex); - list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) { - w1_slave_detach(sl); - } - w1_destroy_master_attributes(dev); - mutex_unlock(&dev->mutex); - atomic_dec(&dev->refcnt); - continue; - } - - if (test_bit(W1_MASTER_NEED_RECONNECT, &dev->flags)) { - dev_dbg(&dev->dev, "Reconnecting slaves in device %s.\n", dev->name); - mutex_lock(&dev->mutex); - list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) { - if (sl->family->fid == W1_FAMILY_DEFAULT) { - struct w1_reg_num rn; - - memcpy(&rn, &sl->reg_num, sizeof(rn)); - w1_slave_detach(sl); - - w1_attach_slave_device(dev, &rn); - } - } - dev_dbg(&dev->dev, "Reconnecting slaves in device %s has been finished.\n", dev->name); - clear_bit(W1_MASTER_NEED_RECONNECT, &dev->flags); - mutex_unlock(&dev->mutex); - } - } - } - - return 0; -} - void w1_search_process(struct w1_master *dev, u8 search_type) { struct w1_slave *sl, *sln; @@ -932,18 +860,13 @@ static int w1_init(void) goto err_out_master_unregister; } - w1_control_thread = kthread_run(w1_control, NULL, "w1_control"); - if (IS_ERR(w1_control_thread)) { - retval = PTR_ERR(w1_control_thread); - printk(KERN_ERR "Failed to create control thread. err=%d\n", - retval); - goto err_out_slave_unregister; - } - return 0; +#if 0 +/* For undoing the slave register if there was a step after it. */ err_out_slave_unregister: driver_unregister(&w1_slave_driver); +#endif err_out_master_unregister: driver_unregister(&w1_master_driver); @@ -959,13 +882,12 @@ static void w1_fini(void) { struct w1_master *dev; + /* Set netlink removal messages and some cleanup */ list_for_each_entry(dev, &w1_masters, w1_master_entry) __w1_remove_master_device(dev); w1_fini_netlink(); - kthread_stop(w1_control_thread); - driver_unregister(&w1_slave_driver); driver_unregister(&w1_master_driver); bus_unregister(&w1_bus_type); diff --git a/drivers/w1/w1.h b/drivers/w1/w1.h index f1df5343f4ad..13e0ea880bf8 100644 --- a/drivers/w1/w1.h +++ b/drivers/w1/w1.h @@ -77,7 +77,7 @@ struct w1_slave struct completion released; }; -typedef void (* w1_slave_found_callback)(void *, u64); +typedef void (*w1_slave_found_callback)(struct w1_master *, u64); /** @@ -142,12 +142,14 @@ struct w1_bus_master */ u8 (*reset_bus)(void *); - /** Really nice hardware can handles the different types of ROM search */ - void (*search)(void *, u8, w1_slave_found_callback); + /** Really nice hardware can handles the different types of ROM search + * w1_master* is passed to the slave found callback. + */ + void (*search)(void *, struct w1_master *, + u8, w1_slave_found_callback); }; #define W1_MASTER_NEED_EXIT 0 -#define W1_MASTER_NEED_RECONNECT 1 struct w1_master { @@ -181,12 +183,21 @@ struct w1_master }; int w1_create_master_attributes(struct w1_master *); +void w1_destroy_master_attributes(struct w1_master *master); void w1_search(struct w1_master *dev, u8 search_type, w1_slave_found_callback cb); void w1_search_devices(struct w1_master *dev, u8 search_type, w1_slave_found_callback cb); struct w1_slave *w1_search_slave(struct w1_reg_num *id); void w1_search_process(struct w1_master *dev, u8 search_type); struct w1_master *w1_search_master_id(u32 id); +/* Disconnect and reconnect devices in the given family. Used for finding + * unclaimed devices after a family has been registered or releasing devices + * after a family has been unregistered. Set attach to 1 when a new family + * has just been registered, to 0 when it has been unregistered. + */ +void w1_reconnect_slaves(struct w1_family *f, int attach); +void w1_slave_detach(struct w1_slave *sl); + u8 w1_triplet(struct w1_master *dev, int bdir); void w1_write_8(struct w1_master *, u8); int w1_reset_bus(struct w1_master *); diff --git a/drivers/w1/w1_family.c b/drivers/w1/w1_family.c index a3c95bd6890a..8c35f9ccb689 100644 --- a/drivers/w1/w1_family.c +++ b/drivers/w1/w1_family.c @@ -53,7 +53,8 @@ int w1_register_family(struct w1_family *newf) } spin_unlock(&w1_flock); - w1_reconnect_slaves(newf); + /* check default devices against the new set of drivers */ + w1_reconnect_slaves(newf, 1); return ret; } @@ -77,6 +78,9 @@ void w1_unregister_family(struct w1_family *fent) spin_unlock(&w1_flock); + /* deatch devices using this family code */ + w1_reconnect_slaves(fent, 0); + while (atomic_read(&fent->refcnt)) { printk(KERN_INFO "Waiting for family %u to become free: refcnt=%d.\n", fent->fid, atomic_read(&fent->refcnt)); diff --git a/drivers/w1/w1_family.h b/drivers/w1/w1_family.h index ef1e1dafa19a..296a87edd922 100644 --- a/drivers/w1/w1_family.h +++ b/drivers/w1/w1_family.h @@ -63,6 +63,5 @@ void __w1_family_get(struct w1_family *); struct w1_family * w1_family_registered(u8); void w1_unregister_family(struct w1_family *); int w1_register_family(struct w1_family *); -void w1_reconnect_slaves(struct w1_family *f); #endif /* __W1_FAMILY_H */ diff --git a/drivers/w1/w1_int.c b/drivers/w1/w1_int.c index 6840dfebe4d4..ed3228017dad 100644 --- a/drivers/w1/w1_int.c +++ b/drivers/w1/w1_int.c @@ -148,10 +148,22 @@ err_out_free_dev: void __w1_remove_master_device(struct w1_master *dev) { struct w1_netlink_msg msg; + struct w1_slave *sl, *sln; set_bit(W1_MASTER_NEED_EXIT, &dev->flags); kthread_stop(dev->thread); + mutex_lock(&w1_mlock); + list_del(&dev->w1_master_entry); + mutex_unlock(&w1_mlock); + + mutex_lock(&dev->mutex); + list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) + w1_slave_detach(sl); + w1_destroy_master_attributes(dev); + mutex_unlock(&dev->mutex); + atomic_dec(&dev->refcnt); + while (atomic_read(&dev->refcnt)) { dev_info(&dev->dev, "Waiting for %s to become free: refcnt=%d.\n", dev->name, atomic_read(&dev->refcnt)); diff --git a/drivers/w1/w1_io.c b/drivers/w1/w1_io.c index 30b6fbf83bd4..0056ef69009b 100644 --- a/drivers/w1/w1_io.c +++ b/drivers/w1/w1_io.c @@ -277,7 +277,8 @@ void w1_search_devices(struct w1_master *dev, u8 search_type, w1_slave_found_cal { dev->attempts++; if (dev->bus_master->search) - dev->bus_master->search(dev->bus_master->data, search_type, cb); + dev->bus_master->search(dev->bus_master->data, dev, + search_type, cb); else w1_search(dev, search_type, cb); } -- 2.20.1