[PATCH v3 2/9] driver core: Replace dev->can_match with DEV_FLAG_CAN_MATCH

[Douglas Anderson]

In C, bitfields are not necessarily safe to modify from multiple
threads without locking. Switch "can_match" over to the "flags" field
so modifications are safe.

Cc: Saravana Kannan <saravanak@xxxxxxxxxx>
Signed-off-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
---
Not fixing any known bugs; problem is theoretical and found by code
inspection. Change is done somewhat manually and only lightly tested
(mostly compile-time tested).

Changes in v3:
- New

 drivers/base/core.c    | 10 +++++-----
 drivers/base/dd.c      |  8 ++++----
 include/linux/device.h |  8 ++++----
 3 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 8d4028a2165f..cbdfee887833 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -1011,7 +1011,7 @@ static void device_links_missing_supplier(struct device *dev)
 
 static bool dev_is_best_effort(struct device *dev)
 {
-	return (fw_devlink_best_effort && dev->can_match) ||
+	return (fw_devlink_best_effort && test_bit(DEV_FLAG_CAN_MATCH, &dev->flags)) ||
 		(dev->fwnode && (dev->fwnode->flags & FWNODE_FLAG_BEST_EFFORT));
 }
 
@@ -1079,7 +1079,7 @@ int device_links_check_suppliers(struct device *dev)
 
 			if (dev_is_best_effort(dev) &&
 			    device_link_test(link, DL_FLAG_INFERRED) &&
-			    !link->supplier->can_match) {
+			    !test_bit(DEV_FLAG_CAN_MATCH, &link->supplier->flags)) {
 				ret = -EAGAIN;
 				continue;
 			}
@@ -1370,7 +1370,7 @@ void device_links_driver_bound(struct device *dev)
 		} else if (dev_is_best_effort(dev) &&
 			   device_link_test(link, DL_FLAG_INFERRED) &&
 			   link->status != DL_STATE_CONSUMER_PROBE &&
-			   !link->supplier->can_match) {
+			   !test_bit(DEV_FLAG_CAN_MATCH, &link->supplier->flags)) {
 			/*
 			 * When dev_is_best_effort() is true, we ignore device
 			 * links to suppliers that don't have a driver.  If the
@@ -1758,7 +1758,7 @@ static int fw_devlink_no_driver(struct device *dev, void *data)
 {
 	struct device_link *link = to_devlink(dev);
 
-	if (!link->supplier->can_match)
+	if (!test_bit(DEV_FLAG_CAN_MATCH, &link->supplier->flags))
 		fw_devlink_relax_link(link);
 
 	return 0;
@@ -3708,7 +3708,7 @@ int device_add(struct device *dev)
 	 * match with any driver, don't block its consumers from probing in
 	 * case the consumer device is able to operate without this supplier.
 	 */
-	if (dev->fwnode && fw_devlink_drv_reg_done && !dev->can_match)
+	if (dev->fwnode && fw_devlink_drv_reg_done && !test_bit(DEV_FLAG_CAN_MATCH, &dev->flags))
 		fw_devlink_unblock_consumers(dev);
 
 	if (parent)
diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 3aead51173f8..66df31696349 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -132,7 +132,7 @@ static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func);
 
 void driver_deferred_probe_add(struct device *dev)
 {
-	if (!dev->can_match)
+	if (!test_bit(DEV_FLAG_CAN_MATCH, &dev->flags))
 		return;
 
 	mutex_lock(&deferred_probe_mutex);
@@ -860,7 +860,7 @@ static int __driver_probe_device(const struct device_driver *drv, struct device
 	if (!test_bit(DEV_FLAG_READY_TO_PROBE, &dev->flags))
 		return dev_err_probe(dev, -EPROBE_DEFER, "Device not ready to probe\n");
 
-	dev->can_match = true;
+	set_bit(DEV_FLAG_CAN_MATCH, &dev->flags);
 	dev_dbg(dev, "bus: '%s': %s: matched device with driver %s\n",
 		drv->bus->name, __func__, drv->name);
 
@@ -1006,7 +1006,7 @@ static int __device_attach_driver(struct device_driver *drv, void *_data)
 		return 0;
 	} else if (ret == -EPROBE_DEFER) {
 		dev_dbg(dev, "Device match requests probe deferral\n");
-		dev->can_match = true;
+		set_bit(DEV_FLAG_CAN_MATCH, &dev->flags);
 		driver_deferred_probe_add(dev);
 		/*
 		 * Device can't match with a driver right now, so don't attempt
@@ -1258,7 +1258,7 @@ static int __driver_attach(struct device *dev, void *data)
 		return 0;
 	} else if (ret == -EPROBE_DEFER) {
 		dev_dbg(dev, "Device match requests probe deferral\n");
-		dev->can_match = true;
+		set_bit(DEV_FLAG_CAN_MATCH, &dev->flags);
 		driver_deferred_probe_add(dev);
 		/*
 		 * Driver could not match with device, but may match with
diff --git a/include/linux/device.h b/include/linux/device.h
index 5b7ace5921aa..7e5737c6d7d1 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -465,9 +465,13 @@ struct device_physical_location {
  *
  * @DEV_FLAG_READY_TO_PROBE: If set then device_add() has finished enough
  *		initialization that probe could be called.
+ * @DEV_FLAG_CAN_MATCH: The device has matched with a driver at least once or it
+ *		is in a bus (like AMBA) which can't check for matching drivers
+ *		until other devices probe successfully.
  */
 enum struct_device_flags {
 	DEV_FLAG_READY_TO_PROBE,
+	DEV_FLAG_CAN_MATCH,
 };
 
 /**
@@ -552,9 +556,6 @@ enum struct_device_flags {
  * @state_synced: The hardware state of this device has been synced to match
  *		  the software state of this device by calling the driver/bus
  *		  sync_state() callback.
- * @can_match:	The device has matched with a driver at least once or it is in
- *		a bus (like AMBA) which can't check for matching drivers until
- *		other devices probe successfully.
  * @dma_coherent: this particular device is dma coherent, even if the
  *		architecture supports non-coherent devices.
  * @dma_ops_bypass: If set to %true then the dma_ops are bypassed for the
@@ -673,7 +674,6 @@ struct device {
 	bool			offline:1;
 	bool			of_node_reused:1;
 	bool			state_synced:1;
-	bool			can_match:1;
 #if defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_DEVICE) || \
     defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU) || \
     defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU_ALL)
-- 
2.53.0.1213.gd9a14994de-goog