Add an additional bit flag to the device struct named async_probe. This
additional flag allows us to guarantee ordering between probe and remove
operations.
This allows us to guarantee that if we execute a remove operation on a
given interface it will not attempt to update the driver member
asynchronously following the earlier operation. Previously this guarantee
was not present and could result in us attempting to remove a driver from
an interface only to have it attempt to attach the driver later when we
finally complete the deferred asynchronous probe call.
Reviewed-by: Bart Van Assche <bvanass...@acm.org>
Signed-off-by: Alexander Duyck <alexander.h.du...@linux.intel.com>
---
drivers/base/dd.c | 16 ++++++++++++++++
include/linux/device.h | 3 +++
2 files changed, 19 insertions(+)
diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 88713f182086..ef3f70a7cb5a 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -774,6 +774,10 @@ static void __device_attach_async_helper(void *_dev,
async_cookie_t cookie)
device_lock(dev);
+ /* nothing to do if async_probe has been cleared */
+ if (!dev->async_probe)
+ goto out_unlock;
+
if (dev->parent)
pm_runtime_get_sync(dev->parent);
@@ -785,6 +789,9 @@ static void __device_attach_async_helper(void *_dev,
async_cookie_t cookie)
if (dev->parent)
pm_runtime_put(dev->parent);
+ /* We made our attempt at an async_probe, clear the flag */
+ dev->async_probe = false;
+out_unlock:
device_unlock(dev);
put_device(dev);
@@ -829,6 +836,7 @@ static int __device_attach(struct device *dev, bool
allow_async)
*/
dev_dbg(dev, "scheduling asynchronous probe\n");
get_device(dev);
+ dev->async_probe = true;
async_schedule(__device_attach_async_helper, dev);
} else {
pm_request_idle(dev);
@@ -929,6 +937,14 @@ static void __device_release_driver(struct device *dev,
struct device *parent)
{
struct device_driver *drv;
+ /*
+ * In the event that we are asked to release the driver on an
+ * interface that is still waiting on a probe we can just terminate
+ * the probe by setting async_probe to false. When the async call
+ * is finally completed it will see this state and just exit.
+ */
+ dev->async_probe = false;
+
drv = dev->driver;
if (drv) {
while (device_links_busy(dev)) {
diff --git a/include/linux/device.h b/include/linux/device.h
index 1b25c7a43f4c..4d2eb2c74149 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -957,6 +957,8 @@ struct dev_links_info {
* device.
* @dma_coherent: this particular device is dma coherent, even if the
* architecture supports non-coherent devices.
+ * @async_probe: This device has an asynchronous probe event pending. Should
+ * only be updated while holding device lock.
*
* At the lowest level, every device in a Linux system is represented by an
* instance of struct device. The device structure contains the information
@@ -1051,6 +1053,7 @@ struct device {
defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU_ALL)
bool dma_coherent:1;
#endif
+ bool async_probe:1;
};
static inline struct device *kobj_to_dev(struct kobject *kobj)
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