| From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 |
| From: Saravana Kannan <saravanak@google.com> |
| Date: Thu, 14 Nov 2019 14:56:45 -0800 |
| Subject: FROMGIT: 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> |
| (cherry-pick from commit 26e77708fdc20ec6c24759602640ac42b8e4e88a |
| https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core.git driver-core-next) |
| Change-Id: I0787645c410137f9f91fb808675ccf7dd1b5a7c0 |
| --- |
| drivers/base/core.c | 79 ++++++++++++++++++++++++++++++++++++++++----- |
| 1 file 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) |