w1: process w1 netlink commands in w1_process thread
Netlink is a socket interface and is expected to be asynchronous.
Clients can now make w1 requests without blocking by making use of the
w1_master thread to process netlink commands which was previously only
used for doing an automatic bus search.
Signed-off-by: David Fries <David@Fries.net>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/w1/w1.c b/drivers/w1/w1.c
index 97b35cb..53846c7 100644
--- a/drivers/w1/w1.c
+++ b/drivers/w1/w1.c
@@ -79,19 +79,10 @@
{
struct w1_slave *sl = dev_to_w1_slave(dev);
- dev_dbg(dev, "%s: Releasing %s.\n", __func__, sl->name);
-
- while (atomic_read(&sl->refcnt)) {
- dev_dbg(dev, "Waiting for %s to become free: refcnt=%d.\n",
- sl->name, atomic_read(&sl->refcnt));
- if (msleep_interruptible(1000))
- flush_signals(current);
- }
+ dev_dbg(dev, "%s: Releasing %s [%p]\n", __func__, sl->name, sl);
w1_family_put(sl->family);
sl->master->slave_count--;
-
- complete(&sl->released);
}
static ssize_t name_show(struct device *dev, struct device_attribute *attr, char *buf)
@@ -277,7 +268,6 @@
mutex_lock(&md->mutex);
md->enable_pullup = tmp;
mutex_unlock(&md->mutex);
- wake_up_process(md->thread);
return count;
}
@@ -370,23 +360,20 @@
{
struct w1_master *md = dev_to_w1_master(dev);
int c = PAGE_SIZE;
+ struct list_head *ent, *n;
+ struct w1_slave *sl = NULL;
- mutex_lock(&md->mutex);
+ mutex_lock(&md->list_mutex);
- if (md->slave_count == 0)
- c -= snprintf(buf + PAGE_SIZE - c, c, "not found.\n");
- else {
- struct list_head *ent, *n;
- struct w1_slave *sl;
+ list_for_each_safe(ent, n, &md->slist) {
+ sl = list_entry(ent, struct w1_slave, w1_slave_entry);
- list_for_each_safe(ent, n, &md->slist) {
- sl = list_entry(ent, struct w1_slave, w1_slave_entry);
-
- c -= snprintf(buf + PAGE_SIZE - c, c, "%s\n", sl->name);
- }
+ c -= snprintf(buf + PAGE_SIZE - c, c, "%s\n", sl->name);
}
+ if (!sl)
+ c -= snprintf(buf + PAGE_SIZE - c, c, "not found.\n");
- mutex_unlock(&md->mutex);
+ mutex_unlock(&md->list_mutex);
return PAGE_SIZE - c;
}
@@ -440,19 +427,22 @@
}
/* Searches the slaves in the w1_master and returns a pointer or NULL.
- * Note: must hold the mutex
+ * Note: must not hold list_mutex
*/
struct w1_slave *w1_slave_search_device(struct w1_master *dev,
struct w1_reg_num *rn)
{
struct w1_slave *sl;
+ mutex_lock(&dev->list_mutex);
list_for_each_entry(sl, &dev->slist, w1_slave_entry) {
if (sl->reg_num.family == rn->family &&
sl->reg_num.id == rn->id &&
sl->reg_num.crc == rn->crc) {
+ mutex_unlock(&dev->list_mutex);
return sl;
}
}
+ mutex_unlock(&dev->list_mutex);
return NULL;
}
@@ -509,7 +499,10 @@
mutex_lock(&md->mutex);
sl = w1_slave_search_device(md, &rn);
if (sl) {
- w1_slave_detach(sl);
+ result = w1_slave_detach(sl);
+ /* refcnt 0 means it was detached in the call */
+ if (result == 0)
+ result = count;
} else {
dev_info(dev, "Device %02x-%012llx doesn't exists\n", rn.family,
(unsigned long long)rn.id);
@@ -704,7 +697,9 @@
dev_set_uevent_suppress(&sl->dev, false);
kobject_uevent(&sl->dev.kobj, KOBJ_ADD);
+ mutex_lock(&sl->master->list_mutex);
list_add_tail(&sl->w1_slave_entry, &sl->master->slist);
+ mutex_unlock(&sl->master->list_mutex);
return 0;
}
@@ -731,8 +726,8 @@
memset(&msg, 0, sizeof(msg));
memcpy(&sl->reg_num, rn, sizeof(sl->reg_num));
- atomic_set(&sl->refcnt, 0);
- init_completion(&sl->released);
+ atomic_set(&sl->refcnt, 1);
+ atomic_inc(&sl->master->refcnt);
/* slave modules need to be loaded in a context with unlocked mutex */
mutex_unlock(&dev->mutex);
@@ -772,23 +767,48 @@
return 0;
}
-void w1_slave_detach(struct w1_slave *sl)
+int w1_unref_slave(struct w1_slave *sl)
{
- struct w1_netlink_msg msg;
+ struct w1_master *dev = sl->master;
+ int refcnt;
+ mutex_lock(&dev->list_mutex);
+ refcnt = atomic_sub_return(1, &sl->refcnt);
+ if (refcnt == 0) {
+ struct w1_netlink_msg msg;
- dev_dbg(&sl->dev, "%s: detaching %s [%p].\n", __func__, sl->name, sl);
+ dev_dbg(&sl->dev, "%s: detaching %s [%p].\n", __func__,
+ sl->name, sl);
- list_del(&sl->w1_slave_entry);
+ list_del(&sl->w1_slave_entry);
- memset(&msg, 0, sizeof(msg));
- memcpy(msg.id.id, &sl->reg_num, sizeof(msg.id));
- msg.type = W1_SLAVE_REMOVE;
- w1_netlink_send(sl->master, &msg);
+ memset(&msg, 0, sizeof(msg));
+ memcpy(msg.id.id, &sl->reg_num, sizeof(msg.id));
+ msg.type = W1_SLAVE_REMOVE;
+ w1_netlink_send(sl->master, &msg);
- device_unregister(&sl->dev);
+ device_unregister(&sl->dev);
+ #ifdef DEBUG
+ memset(sl, 0, sizeof(*sl));
+ #endif
+ kfree(sl);
+ }
+ atomic_dec(&dev->refcnt);
+ mutex_unlock(&dev->list_mutex);
+ return refcnt;
+}
- wait_for_completion(&sl->released);
- kfree(sl);
+int w1_slave_detach(struct w1_slave *sl)
+{
+ /* Only detach a slave once as it decreases the refcnt each time. */
+ int destroy_now;
+ mutex_lock(&sl->master->list_mutex);
+ destroy_now = !test_bit(W1_SLAVE_DETACH, &sl->flags);
+ set_bit(W1_SLAVE_DETACH, &sl->flags);
+ mutex_unlock(&sl->master->list_mutex);
+
+ if (destroy_now)
+ destroy_now = !w1_unref_slave(sl);
+ return destroy_now ? 0 : -EBUSY;
}
struct w1_master *w1_search_master_id(u32 id)
@@ -817,7 +837,7 @@
mutex_lock(&w1_mlock);
list_for_each_entry(dev, &w1_masters, w1_master_entry) {
- mutex_lock(&dev->mutex);
+ mutex_lock(&dev->list_mutex);
list_for_each_entry(sl, &dev->slist, w1_slave_entry) {
if (sl->reg_num.family == id->family &&
sl->reg_num.id == id->id &&
@@ -828,7 +848,7 @@
break;
}
}
- mutex_unlock(&dev->mutex);
+ mutex_unlock(&dev->list_mutex);
if (found)
break;
@@ -848,6 +868,7 @@
dev_dbg(&dev->dev, "Reconnecting slaves in device %s "
"for family %02x.\n", dev->name, f->fid);
mutex_lock(&dev->mutex);
+ mutex_lock(&dev->list_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
@@ -859,14 +880,19 @@
(!attach && sl->family->fid == f->fid)) {
struct w1_reg_num rn;
+ mutex_unlock(&dev->list_mutex);
memcpy(&rn, &sl->reg_num, sizeof(rn));
- w1_slave_detach(sl);
-
- w1_attach_slave_device(dev, &rn);
+ /* If it was already in use let the automatic
+ * scan pick it up again later.
+ */
+ if (!w1_slave_detach(sl))
+ w1_attach_slave_device(dev, &rn);
+ mutex_lock(&dev->list_mutex);
}
}
dev_dbg(&dev->dev, "Reconnecting slaves in device %s "
"has been finished.\n", dev->name);
+ mutex_unlock(&dev->list_mutex);
mutex_unlock(&dev->mutex);
}
mutex_unlock(&w1_mlock);
@@ -1020,17 +1046,24 @@
{
struct w1_slave *sl, *sln;
+ mutex_lock(&dev->list_mutex);
list_for_each_entry(sl, &dev->slist, w1_slave_entry)
clear_bit(W1_SLAVE_ACTIVE, &sl->flags);
+ mutex_unlock(&dev->list_mutex);
w1_search_devices(dev, search_type, cb);
+ mutex_lock(&dev->list_mutex);
list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
- if (!test_bit(W1_SLAVE_ACTIVE, &sl->flags) && !--sl->ttl)
+ if (!test_bit(W1_SLAVE_ACTIVE, &sl->flags) && !--sl->ttl) {
+ mutex_unlock(&dev->list_mutex);
w1_slave_detach(sl);
+ mutex_lock(&dev->list_mutex);
+ }
else if (test_bit(W1_SLAVE_ACTIVE, &sl->flags))
sl->ttl = dev->slave_ttl;
}
+ mutex_unlock(&dev->list_mutex);
if (dev->search_count > 0)
dev->search_count--;
@@ -1041,6 +1074,26 @@
w1_search_process_cb(dev, search_type, w1_slave_found);
}
+int w1_process_callbacks(struct w1_master *dev)
+{
+ int ret = 0;
+ struct w1_async_cmd *async_cmd, *async_n;
+
+ /* The list can be added to in another thread, loop until it is empty */
+ while (!list_empty(&dev->async_list)) {
+ list_for_each_entry_safe(async_cmd, async_n, &dev->async_list,
+ async_entry) {
+ /* drop the lock, if it is a search it can take a long
+ * time */
+ mutex_unlock(&dev->list_mutex);
+ async_cmd->cb(dev, async_cmd);
+ ret = 1;
+ mutex_lock(&dev->list_mutex);
+ }
+ }
+ return ret;
+}
+
int w1_process(void *data)
{
struct w1_master *dev = (struct w1_master *) data;
@@ -1048,23 +1101,46 @@
* time can be calculated in jiffies once.
*/
const unsigned long jtime = msecs_to_jiffies(w1_timeout * 1000);
+ /* remainder if it woke up early */
+ unsigned long jremain = 0;
- while (!kthread_should_stop()) {
- if (dev->search_count) {
+ for (;;) {
+
+ if (!jremain && dev->search_count) {
mutex_lock(&dev->mutex);
w1_search_process(dev, W1_SEARCH);
mutex_unlock(&dev->mutex);
}
+ mutex_lock(&dev->list_mutex);
+ /* Note, w1_process_callback drops the lock while processing,
+ * but locks it again before returning.
+ */
+ if (!w1_process_callbacks(dev) && jremain) {
+ /* a wake up is either to stop the thread, process
+ * callbacks, or search, it isn't process callbacks, so
+ * schedule a search.
+ */
+ jremain = 1;
+ }
+
try_to_freeze();
__set_current_state(TASK_INTERRUPTIBLE);
+ /* hold list_mutex until after interruptible to prevent loosing
+ * the wakeup signal when async_cmd is added.
+ */
+ mutex_unlock(&dev->list_mutex);
+
if (kthread_should_stop())
break;
/* Only sleep when the search is active. */
- if (dev->search_count)
- schedule_timeout(jtime);
+ if (dev->search_count) {
+ if (!jremain)
+ jremain = jtime;
+ jremain = schedule_timeout(jremain);
+ }
else
schedule();
}