From c30c9b15187e977ab5928f7276e9dfcd8d6f9460 Mon Sep 17 00:00:00 2001 From: David Fries Date: Wed, 15 Oct 2008 22:04:38 -0700 Subject: 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/w1.c | 146 +++++++++++++------------------------------------------- 1 file changed, 34 insertions(+), 112 deletions(-) (limited to 'drivers/w1/w1.c') diff --git a/drivers/w1/w1.c b/drivers/w1/w1.c index 7293c9b..25640f6 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); -- cgit v1.1