[PATCH 3/30] W1: don't delay search start

Evgeniy Polyakov
2008-07-11T13:52:28Z

Move the creation of the w1_process thread to after the device has
been initialized. This way w1_process doesn't have to check to see if
it has been initialized and the bus search can proceed without
sleeping. That also eliminates two checks in the w1_process loop.
The sleep now happens at the end of the loop not the beginning.

Also added a comment for why the atomic_set was 2.

Signed-off-by: David Fries <david@fries.net>
Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>

---
drivers/w1/w1.c | 19 ++++++-------------
drivers/w1/w1_int.c | 26 +++++++++++++++++---------
2 files changed, 23 insertions(+), 22 deletions(-)

diff --git a/drivers/w1/w1.c b/drivers/w1/w1.c
index aac03f1..730faa4 100644
--- a/drivers/w1/w1.c
+++ b/drivers/w1/w1.c
@@ -813,21 +813,14 @@ int w1_process(void *data)
struct w1_master *dev = (struct w1_master *) data;

while (!kthread_should_stop() && !test_bit(W1_MASTER_NEED_EXIT, &dev->flags)) {
+ if (dev->search_count) {
+ mutex_lock(&dev->mutex);
+ w1_search_process(dev, W1_SEARCH);
+ mutex_unlock(&dev->mutex);
+ }
+
try_to_freeze();
msleep_interruptible(w1_timeout * 1000);
-
- if (kthread_should_stop() || test_bit(W1_MASTER_NEED_EXIT, &dev->flags))
- break;
-
- if (!dev->initialized)
- continue;
-
- if (dev->search_count == 0)
- continue;
-
- mutex_lock(&dev->mutex);
- w1_search_process(dev, W1_SEARCH);
- mutex_unlock(&dev->mutex);
}

atomic_dec(&dev->refcnt);
diff --git a/drivers/w1/w1_int.c b/drivers/w1/w1_int.c
index ed32280..36ff402 100644
--- a/drivers/w1/w1_int.c
+++ b/drivers/w1/w1_int.c
@@ -61,6 +61,9 @@ static struct w1_master * w1_alloc_dev(u32 id, int slave_count, int slave_ttl,
dev->slave_ttl = slave_ttl;
dev->search_count = -1; /* continual scan */

+ /* 1 for w1_process to decrement
+ * 1 for __w1_remove_master_device to decrement
+ */
atomic_set(&dev->refcnt, 2);

INIT_LIST_HEAD(&dev->slist);
@@ -109,23 +112,23 @@ int w1_add_master_device(struct w1_bus_master *master)
if (!dev)
return -ENOMEM;

+ retval = w1_create_master_attributes(dev);
+ if (retval)
+ goto err_out_free_dev;
+
+ memcpy(dev->bus_master, master, sizeof(struct w1_bus_master));
+
+ dev->initialized = 1;
+
dev->thread = kthread_run(&w1_process, dev, "%s", dev->name);
if (IS_ERR(dev->thread)) {
retval = PTR_ERR(dev->thread);
dev_err(&dev->dev,
"Failed to create new kernel thread. err=%d\n",
retval);
- goto err_out_free_dev;
+ goto err_out_rm_attr;
}

- retval = w1_create_master_attributes(dev);
- if (retval)
- goto err_out_kill_thread;
-
- memcpy(dev->bus_master, master, sizeof(struct w1_bus_master));
-
- dev->initialized = 1;
-
mutex_lock(&w1_mlock);
list_add(&dev->w1_master_entry, &w1_masters);
mutex_unlock(&w1_mlock);
@@ -137,8 +140,13 @@ int w1_add_master_device(struct w1_bus_master *master)

return 0;

+#if 0 /* Thread cleanup code, not required currently. */
err_out_kill_thread:
+ set_bit(W1_MASTER_NEED_EXIT, &dev->flags);
kthread_stop(dev->thread);
+#endif
+err_out_rm_attr:
+ w1_destroy_master_attributes(dev);
err_out_free_dev:
w1_free_dev(dev);

--
1.4.4.4