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authorSaravana Kannan <saravanak@google.com>2019-11-14 14:56:45 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-11-15 10:06:54 +0800
commit26e77708fdc20ec6c24759602640ac42b8e4e88a (patch)
treea98f1ee40d025cd63261e38e8b1ad023086f6894 /drivers/base
parent71564a26e3e9d29d3d8901eb32647c2c3a807e1f (diff)
driver core: Allow device link operations inside sync_state()
Some sync_state() implementations might need to call APIs that in turn make calls to device link APIs. So, do the sync_state() callbacks without holding the device link lock. Signed-off-by: Saravana Kannan <saravanak@google.com> Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Link: https://lore.kernel.org/r/20191114225646.251277-1-saravanak@google.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/base')
-rw-r--r--drivers/base/core.c79
1 files changed, 71 insertions, 8 deletions
diff --git a/drivers/base/core.c b/drivers/base/core.c
index e6d3e6d485da..42a672456432 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -695,7 +695,26 @@ int device_links_check_suppliers(struct device *dev)
return ret;
}
-static void __device_links_supplier_sync_state(struct device *dev)
+/**
+ * __device_links_queue_sync_state - Queue a device for sync_state() callback
+ * @dev: Device to call sync_state() on
+ * @list: List head to queue the @dev on
+ *
+ * Queues a device for a sync_state() callback when the device links write lock
+ * isn't held. This allows the sync_state() execution flow to use device links
+ * APIs. The caller must ensure this function is called with
+ * device_links_write_lock() held.
+ *
+ * This function does a get_device() to make sure the device is not freed while
+ * on this list.
+ *
+ * So the caller must also ensure that device_links_flush_sync_list() is called
+ * as soon as the caller releases device_links_write_lock(). This is necessary
+ * to make sure the sync_state() is called in a timely fashion and the
+ * put_device() is called on this device.
+ */
+static void __device_links_queue_sync_state(struct device *dev,
+ struct list_head *list)
{
struct device_link *link;
@@ -709,12 +728,45 @@ static void __device_links_supplier_sync_state(struct device *dev)
return;
}
- if (dev->bus->sync_state)
- dev->bus->sync_state(dev);
- else if (dev->driver && dev->driver->sync_state)
- dev->driver->sync_state(dev);
-
+ /*
+ * Set the flag here to avoid adding the same device to a list more
+ * than once. This can happen if new consumers get added to the device
+ * and probed before the list is flushed.
+ */
dev->state_synced = true;
+
+ if (WARN_ON(!list_empty(&dev->links.defer_sync)))
+ return;
+
+ get_device(dev);
+ list_add_tail(&dev->links.defer_sync, list);
+}
+
+/**
+ * device_links_flush_sync_list - Call sync_state() on a list of devices
+ * @list: List of devices to call sync_state() on
+ *
+ * Calls sync_state() on all the devices that have been queued for it. This
+ * function is used in conjunction with __device_links_queue_sync_state().
+ */
+static void device_links_flush_sync_list(struct list_head *list)
+{
+ struct device *dev, *tmp;
+
+ list_for_each_entry_safe(dev, tmp, list, links.defer_sync) {
+ list_del_init(&dev->links.defer_sync);
+
+ device_lock(dev);
+
+ if (dev->bus->sync_state)
+ dev->bus->sync_state(dev);
+ else if (dev->driver && dev->driver->sync_state)
+ dev->driver->sync_state(dev);
+
+ device_unlock(dev);
+
+ put_device(dev);
+ }
}
void device_links_supplier_sync_state_pause(void)
@@ -727,6 +779,7 @@ void device_links_supplier_sync_state_pause(void)
void device_links_supplier_sync_state_resume(void)
{
struct device *dev, *tmp;
+ LIST_HEAD(sync_list);
device_links_write_lock();
if (!defer_sync_state_count) {
@@ -738,11 +791,17 @@ void device_links_supplier_sync_state_resume(void)
goto out;
list_for_each_entry_safe(dev, tmp, &deferred_sync, links.defer_sync) {
- __device_links_supplier_sync_state(dev);
+ /*
+ * Delete from deferred_sync list before queuing it to
+ * sync_list because defer_sync is used for both lists.
+ */
list_del_init(&dev->links.defer_sync);
+ __device_links_queue_sync_state(dev, &sync_list);
}
out:
device_links_write_unlock();
+
+ device_links_flush_sync_list(&sync_list);
}
static int sync_state_resume_initcall(void)
@@ -772,6 +831,7 @@ static void __device_links_supplier_defer_sync(struct device *sup)
void device_links_driver_bound(struct device *dev)
{
struct device_link *link;
+ LIST_HEAD(sync_list);
/*
* If a device probes successfully, it's expected to have created all
@@ -815,12 +875,15 @@ void device_links_driver_bound(struct device *dev)
if (defer_sync_state_count)
__device_links_supplier_defer_sync(link->supplier);
else
- __device_links_supplier_sync_state(link->supplier);
+ __device_links_queue_sync_state(link->supplier,
+ &sync_list);
}
dev->links.status = DL_DEV_DRIVER_BOUND;
device_links_write_unlock();
+
+ device_links_flush_sync_list(&sync_list);
}
static void device_link_drop_managed(struct device_link *link)