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 <david@fries.net>
Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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_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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
{
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);