[PATCH 6.6.y] device property: Make modifications of fwnode "flags" thread safe

[Douglas Anderson <dianders@chromium.org>]

In various places in the kernel, we modify the fwnode "flags" member
by doing either:
  fwnode->flags |= SOME_FLAG;
  fwnode->flags &= ~SOME_FLAG;

This type of modification is not thread-safe. If two threads are both
mucking with the flags at the same time then one can clobber the
other.

While flags are often modified while under the "fwnode_link_lock",
this is not universally true.

Create some accessor functions for setting, clearing, and testing the
FWNODE flags and move all users to these accessor functions. New
accessor functions use set_bit() and clear_bit(), which are
thread-safe.

Cc: stable@vger.kernel.org
Fixes: c2c724c868c4 ("driver core: Add fw_devlink_parse_fwtree()")
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Rafael J. Wysocki (Intel) <rafael@kernel.org>
Reviewed-by: Saravana Kannan <saravanak@kernel.org>
Link: https://patch.msgid.link/20260317090112.v2.1.I0a4d03104ecd5103df3d76f66c8d21b1d15a2e38@changeid
[ Fix fwnode_clear_flag() argument alignment, restore dropped blank
  line in fwnode_dev_initialized(), and remove unnecessary parentheses
  around fwnode_test_flag() calls. - Danilo ]
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
(cherry picked from commit f72e77c33e4b5657af35125e75bab249256030f3)
Signed-off-by: Douglas Anderson <dianders@chromium.org>
---
 drivers/base/core.c        | 24 ++++++++++-----------
 drivers/bus/imx-weim.c     |  2 +-
 drivers/i2c/i2c-core-of.c  |  2 +-
 drivers/net/phy/mdio_bus.c |  4 ++--
 drivers/of/base.c          |  2 +-
 drivers/of/dynamic.c       |  2 +-
 drivers/of/platform.c      |  2 +-
 drivers/spi/spi.c          |  2 +-
 include/linux/fwnode.h     | 44 ++++++++++++++++++++++++++++----------
 9 files changed, 53 insertions(+), 31 deletions(-)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index a192ce5bb8f9..a7033e11e38f 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -182,7 +182,7 @@ void fw_devlink_purge_absent_suppliers(struct fwnode_handle *fwnode)
 	if (fwnode->dev)
 		return;
 
-	fwnode->flags |= FWNODE_FLAG_NOT_DEVICE;
+	fwnode_set_flag(fwnode, FWNODE_FLAG_NOT_DEVICE);
 	fwnode_links_purge_consumers(fwnode);
 
 	fwnode_for_each_available_child_node(fwnode, child)
@@ -228,7 +228,7 @@ static void __fw_devlink_pickup_dangling_consumers(struct fwnode_handle *fwnode,
 	if (fwnode->dev && fwnode->dev->bus)
 		return;
 
-	fwnode->flags |= FWNODE_FLAG_NOT_DEVICE;
+	fwnode_set_flag(fwnode, FWNODE_FLAG_NOT_DEVICE);
 	__fwnode_links_move_consumers(fwnode, new_sup);
 
 	fwnode_for_each_available_child_node(fwnode, child)
@@ -1013,7 +1013,7 @@ 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) ||
-		(dev->fwnode && (dev->fwnode->flags & FWNODE_FLAG_BEST_EFFORT));
+		(dev->fwnode && fwnode_test_flag(dev->fwnode, FWNODE_FLAG_BEST_EFFORT));
 }
 
 static struct fwnode_handle *fwnode_links_check_suppliers(
@@ -1729,11 +1729,11 @@ bool fw_devlink_is_strict(void)
 
 static void fw_devlink_parse_fwnode(struct fwnode_handle *fwnode)
 {
-	if (fwnode->flags & FWNODE_FLAG_LINKS_ADDED)
+	if (fwnode_test_flag(fwnode, FWNODE_FLAG_LINKS_ADDED))
 		return;
 
 	fwnode_call_int_op(fwnode, add_links);
-	fwnode->flags |= FWNODE_FLAG_LINKS_ADDED;
+	fwnode_set_flag(fwnode, FWNODE_FLAG_LINKS_ADDED);
 }
 
 static void fw_devlink_parse_fwtree(struct fwnode_handle *fwnode)
@@ -1892,7 +1892,7 @@ static bool fwnode_init_without_drv(struct fwnode_handle *fwnode)
 	struct device *dev;
 	bool ret;
 
-	if (!(fwnode->flags & FWNODE_FLAG_INITIALIZED))
+	if (!fwnode_test_flag(fwnode, FWNODE_FLAG_INITIALIZED))
 		return false;
 
 	dev = get_dev_from_fwnode(fwnode);
@@ -1951,10 +1951,10 @@ static bool __fw_devlink_relax_cycles(struct fwnode_handle *con_handle,
 	 * We aren't trying to find all cycles. Just a cycle between con and
 	 * sup_handle.
 	 */
-	if (sup_handle->flags & FWNODE_FLAG_VISITED)
+	if (fwnode_test_flag(sup_handle, FWNODE_FLAG_VISITED))
 		return false;
 
-	sup_handle->flags |= FWNODE_FLAG_VISITED;
+	fwnode_set_flag(sup_handle, FWNODE_FLAG_VISITED);
 
 	/* Termination condition. */
 	if (sup_handle == con_handle) {
@@ -2024,7 +2024,7 @@ static bool __fw_devlink_relax_cycles(struct fwnode_handle *con_handle,
 	}
 
 out:
-	sup_handle->flags &= ~FWNODE_FLAG_VISITED;
+	fwnode_clear_flag(sup_handle, FWNODE_FLAG_VISITED);
 	put_device(sup_dev);
 	put_device(con_dev);
 	put_device(par_dev);
@@ -2077,7 +2077,7 @@ static int fw_devlink_create_devlink(struct device *con,
 	 * When such a flag is set, we can't create device links where P is the
 	 * supplier of C as that would delay the probe of C.
 	 */
-	if (sup_handle->flags & FWNODE_FLAG_NEEDS_CHILD_BOUND_ON_ADD &&
+	if (fwnode_test_flag(sup_handle, FWNODE_FLAG_NEEDS_CHILD_BOUND_ON_ADD) &&
 	    fwnode_is_ancestor_of(sup_handle, con->fwnode))
 		return -EINVAL;
 
@@ -2100,7 +2100,7 @@ static int fw_devlink_create_devlink(struct device *con,
 	else
 		flags = FW_DEVLINK_FLAGS_PERMISSIVE;
 
-	if (sup_handle->flags & FWNODE_FLAG_NOT_DEVICE)
+	if (fwnode_test_flag(sup_handle, FWNODE_FLAG_NOT_DEVICE))
 		sup_dev = fwnode_get_next_parent_dev(sup_handle);
 	else
 		sup_dev = get_dev_from_fwnode(sup_handle);
@@ -2112,7 +2112,7 @@ static int fw_devlink_create_devlink(struct device *con,
 		 * supplier device indefinitely.
 		 */
 		if (sup_dev->links.status == DL_DEV_NO_DRIVER &&
-		    sup_handle->flags & FWNODE_FLAG_INITIALIZED) {
+		    fwnode_test_flag(sup_handle, FWNODE_FLAG_INITIALIZED)) {
 			dev_dbg(con,
 				"Not linking %pfwf - dev might never probe\n",
 				sup_handle);
diff --git a/drivers/bus/imx-weim.c b/drivers/bus/imx-weim.c
index f9fd1582f150..5244013d328f 100644
--- a/drivers/bus/imx-weim.c
+++ b/drivers/bus/imx-weim.c
@@ -335,7 +335,7 @@ static int of_weim_notify(struct notifier_block *nb, unsigned long action,
 			 * fw_devlink doesn't skip adding consumers to this
 			 * device.
 			 */
-			rd->dn->fwnode.flags &= ~FWNODE_FLAG_NOT_DEVICE;
+			fwnode_clear_flag(&rd->dn->fwnode, FWNODE_FLAG_NOT_DEVICE);
 			if (!of_platform_device_create(rd->dn, NULL, &pdev->dev)) {
 				dev_err(&pdev->dev,
 					"Failed to create child device '%pOF'\n",
diff --git a/drivers/i2c/i2c-core-of.c b/drivers/i2c/i2c-core-of.c
index a6c407d36800..50e97e2ed2cf 100644
--- a/drivers/i2c/i2c-core-of.c
+++ b/drivers/i2c/i2c-core-of.c
@@ -182,7 +182,7 @@ static int of_i2c_notify(struct notifier_block *nb, unsigned long action,
 		 * Clear the flag before adding the device so that fw_devlink
 		 * doesn't skip adding consumers to this device.
 		 */
-		rd->dn->fwnode.flags &= ~FWNODE_FLAG_NOT_DEVICE;
+		fwnode_clear_flag(&rd->dn->fwnode, FWNODE_FLAG_NOT_DEVICE);
 		client = of_i2c_register_device(adap, rd->dn);
 		if (IS_ERR(client)) {
 			dev_err(&adap->dev, "failed to create client for '%pOF'\n",
diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
index 7da30a6752be..08b32b45126d 100644
--- a/drivers/net/phy/mdio_bus.c
+++ b/drivers/net/phy/mdio_bus.c
@@ -675,8 +675,8 @@ int __mdiobus_register(struct mii_bus *bus, struct module *owner)
 		return -EINVAL;
 
 	if (bus->parent && bus->parent->of_node)
-		bus->parent->of_node->fwnode.flags |=
-					FWNODE_FLAG_NEEDS_CHILD_BOUND_ON_ADD;
+		fwnode_set_flag(&bus->parent->of_node->fwnode,
+				FWNODE_FLAG_NEEDS_CHILD_BOUND_ON_ADD);
 
 	WARN(bus->state != MDIOBUS_ALLOCATED &&
 	     bus->state != MDIOBUS_UNREGISTERED,
diff --git a/drivers/of/base.c b/drivers/of/base.c
index d10248a5c0a5..04c6a3b40429 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -1759,7 +1759,7 @@ void of_alias_scan(void * (*dt_alloc)(u64 size, u64 align))
 		if (name)
 			of_stdout = of_find_node_opts_by_path(name, &of_stdout_options);
 		if (of_stdout)
-			of_stdout->fwnode.flags |= FWNODE_FLAG_BEST_EFFORT;
+			fwnode_set_flag(&of_stdout->fwnode, FWNODE_FLAG_BEST_EFFORT);
 	}
 
 	if (!of_aliases)
diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c
index 18393800546c..ab109bb92cf4 100644
--- a/drivers/of/dynamic.c
+++ b/drivers/of/dynamic.c
@@ -224,7 +224,7 @@ static void __of_attach_node(struct device_node *np)
 	np->sibling = np->parent->child;
 	np->parent->child = np;
 	of_node_clear_flag(np, OF_DETACHED);
-	np->fwnode.flags |= FWNODE_FLAG_NOT_DEVICE;
+	fwnode_set_flag(&np->fwnode, FWNODE_FLAG_NOT_DEVICE);
 
 	raw_spin_unlock_irqrestore(&devtree_lock, flags);
 
diff --git a/drivers/of/platform.c b/drivers/of/platform.c
index ccf7f0ffa67f..18b72f891c5b 100644
--- a/drivers/of/platform.c
+++ b/drivers/of/platform.c
@@ -774,7 +774,7 @@ static int of_platform_notify(struct notifier_block *nb,
 		 * Clear the flag before adding the device so that fw_devlink
 		 * doesn't skip adding consumers to this device.
 		 */
-		rd->dn->fwnode.flags &= ~FWNODE_FLAG_NOT_DEVICE;
+		fwnode_clear_flag(&rd->dn->fwnode, FWNODE_FLAG_NOT_DEVICE);
 		/* pdev_parent may be NULL when no bus platform device */
 		pdev_parent = of_find_device_by_node(rd->dn->parent);
 		pdev = of_platform_device_create(rd->dn, NULL,
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 91da4cae011c..216a9378f0d6 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -4532,7 +4532,7 @@ static int of_spi_notify(struct notifier_block *nb, unsigned long action,
 		 * Clear the flag before adding the device so that fw_devlink
 		 * doesn't skip adding consumers to this device.
 		 */
-		rd->dn->fwnode.flags &= ~FWNODE_FLAG_NOT_DEVICE;
+		fwnode_clear_flag(&rd->dn->fwnode, FWNODE_FLAG_NOT_DEVICE);
 		spi = of_register_spi_device(ctlr, rd->dn);
 		put_device(&ctlr->dev);
 
diff --git a/include/linux/fwnode.h b/include/linux/fwnode.h
index 7efb4493e51c..76680d583852 100644
--- a/include/linux/fwnode.h
+++ b/include/linux/fwnode.h
@@ -12,6 +12,7 @@
 #include <linux/types.h>
 #include <linux/list.h>
 #include <linux/bits.h>
+#include <linux/bitops.h>
 #include <linux/err.h>
 
 struct fwnode_operations;
@@ -31,12 +32,12 @@ struct device;
  *		suppliers. Only enforce ordering with suppliers that have
  *		drivers.
  */
-#define FWNODE_FLAG_LINKS_ADDED			BIT(0)
-#define FWNODE_FLAG_NOT_DEVICE			BIT(1)
-#define FWNODE_FLAG_INITIALIZED			BIT(2)
-#define FWNODE_FLAG_NEEDS_CHILD_BOUND_ON_ADD	BIT(3)
-#define FWNODE_FLAG_BEST_EFFORT			BIT(4)
-#define FWNODE_FLAG_VISITED			BIT(5)
+#define FWNODE_FLAG_LINKS_ADDED			0
+#define FWNODE_FLAG_NOT_DEVICE			1
+#define FWNODE_FLAG_INITIALIZED			2
+#define FWNODE_FLAG_NEEDS_CHILD_BOUND_ON_ADD	3
+#define FWNODE_FLAG_BEST_EFFORT			4
+#define FWNODE_FLAG_VISITED			5
 
 struct fwnode_handle {
 	struct fwnode_handle *secondary;
@@ -44,7 +45,7 @@ struct fwnode_handle {
 	struct device *dev;
 	struct list_head suppliers;
 	struct list_head consumers;
-	u8 flags;
+	unsigned long flags;
 };
 
 /*
@@ -197,16 +198,37 @@ static inline void fwnode_init(struct fwnode_handle *fwnode,
 	INIT_LIST_HEAD(&fwnode->suppliers);
 }
 
+static inline void fwnode_set_flag(struct fwnode_handle *fwnode,
+				   unsigned int bit)
+{
+	set_bit(bit, &fwnode->flags);
+}
+
+static inline void fwnode_clear_flag(struct fwnode_handle *fwnode,
+				     unsigned int bit)
+{
+	clear_bit(bit, &fwnode->flags);
+}
+
+static inline void fwnode_assign_flag(struct fwnode_handle *fwnode,
+				      unsigned int bit, bool value)
+{
+	assign_bit(bit, &fwnode->flags, value);
+}
+
+static inline bool fwnode_test_flag(struct fwnode_handle *fwnode,
+				    unsigned int bit)
+{
+	return test_bit(bit, &fwnode->flags);
+}
+
 static inline void fwnode_dev_initialized(struct fwnode_handle *fwnode,
 					  bool initialized)
 {
 	if (IS_ERR_OR_NULL(fwnode))
 		return;
 
-	if (initialized)
-		fwnode->flags |= FWNODE_FLAG_INITIALIZED;
-	else
-		fwnode->flags &= ~FWNODE_FLAG_INITIALIZED;
+	fwnode_assign_flag(fwnode, FWNODE_FLAG_INITIALIZED, initialized);
 }
 
 extern bool fw_devlink_is_strict(void);
-- 
2.54.0.545.g6539524ca2-goog