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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>
alistair/sunxi64-5.5-dsi
Saravana Kannan 2019-11-14 14:56:45 -08:00 committed by Greg Kroah-Hartman
parent 71564a26e3
commit 26e77708fd
1 changed files with 71 additions and 8 deletions
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79
drivers/base/core.c
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@ -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)