[PATCH v5 7/9] driver core: Replace dev->dma_coherent with dev_dma_coherent()

[PATCH v5 7/9] driver core: Replace dev->dma_coherent with dev_dma_coherent()

[Douglas Anderson]

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

Cc: Christoph Hellwig <hch@lst.de>
Reviewed-by: Rafael J. Wysocki (Intel) <rafael@kernel.org>
Reviewed-by: Danilo Krummrich <dakr@kernel.org>
Acked-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
---
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).

NOTE: even though previously we only took up a bit if
CONFIG_ARCH_HAS_SYNC_DMA_FOR_DEVICE, CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU,
or CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU_ALL, in this change I reserve the
bit unconditionally.  While we could get the "dynamic" behavior by
changing the flags definition to be an unnumbered "enum", Greg has
requested that the numbers be stable.

(no changes since v4)

Changes in v4:
- Use accessor functions for flags

Changes in v3:
- New

 arch/arc/mm/dma.c                 |  4 ++--
 arch/arm/mach-highbank/highbank.c |  2 +-
 arch/arm/mach-mvebu/coherency.c   |  2 +-
 arch/arm/mm/dma-mapping-nommu.c   |  4 ++--
 arch/arm/mm/dma-mapping.c         | 28 ++++++++++++++--------------
 arch/arm64/mm/dma-mapping.c       |  2 +-
 arch/mips/mm/dma-noncoherent.c    |  2 +-
 arch/riscv/mm/dma-noncoherent.c   |  2 +-
 drivers/base/core.c               |  2 +-
 drivers/dma/ti/k3-udma-glue.c     |  6 +++---
 drivers/dma/ti/k3-udma.c          |  6 +++---
 include/linux/device.h            | 11 ++++-------
 include/linux/dma-map-ops.h       |  2 +-
 13 files changed, 35 insertions(+), 38 deletions(-)

diff --git a/arch/arc/mm/dma.c b/arch/arc/mm/dma.c
index 6b85e94f3275..9b9adb02b4c5 100644
--- a/arch/arc/mm/dma.c
+++ b/arch/arc/mm/dma.c
@@ -98,8 +98,8 @@ void arch_setup_dma_ops(struct device *dev, bool coherent)
 	 * DMA buffers.
 	 */
 	if (is_isa_arcv2() && ioc_enable && coherent)
-		dev->dma_coherent = true;
+		dev_set_dma_coherent(dev);
 
 	dev_info(dev, "use %scoherent DMA ops\n",
-		 dev->dma_coherent ? "" : "non");
+		 dev_dma_coherent(dev) ? "" : "non");
 }
diff --git a/arch/arm/mach-highbank/highbank.c b/arch/arm/mach-highbank/highbank.c
index 47335c7dadf8..8b7d0929dac4 100644
--- a/arch/arm/mach-highbank/highbank.c
+++ b/arch/arm/mach-highbank/highbank.c
@@ -98,7 +98,7 @@ static int highbank_platform_notifier(struct notifier_block *nb,
 	if (of_property_read_bool(dev->of_node, "dma-coherent")) {
 		val = readl(sregs_base + reg);
 		writel(val | 0xff01, sregs_base + reg);
-		dev->dma_coherent = true;
+		dev_set_dma_coherent(dev);
 	}
 
 	return NOTIFY_OK;
diff --git a/arch/arm/mach-mvebu/coherency.c b/arch/arm/mach-mvebu/coherency.c
index fa2c1e1aeb96..7234d487ff39 100644
--- a/arch/arm/mach-mvebu/coherency.c
+++ b/arch/arm/mach-mvebu/coherency.c
@@ -95,7 +95,7 @@ static int mvebu_hwcc_notifier(struct notifier_block *nb,
 
 	if (event != BUS_NOTIFY_ADD_DEVICE)
 		return NOTIFY_DONE;
-	dev->dma_coherent = true;
+	dev_set_dma_coherent(dev);
 
 	return NOTIFY_OK;
 }
diff --git a/arch/arm/mm/dma-mapping-nommu.c b/arch/arm/mm/dma-mapping-nommu.c
index fecac107fd0d..c6a70686507b 100644
--- a/arch/arm/mm/dma-mapping-nommu.c
+++ b/arch/arm/mm/dma-mapping-nommu.c
@@ -42,11 +42,11 @@ void arch_setup_dma_ops(struct device *dev, bool coherent)
 		 * enough to check if MPU is in use or not since in absence of
 		 * MPU system memory map is used.
 		 */
-		dev->dma_coherent = cacheid ? coherent : true;
+		dev_assign_dma_coherent(dev, cacheid ? coherent : true);
 	} else {
 		/*
 		 * Assume coherent DMA in case MMU/MPU has not been set up.
 		 */
-		dev->dma_coherent = (get_cr() & CR_M) ? coherent : true;
+		dev_assign_dma_coherent(dev, (get_cr() & CR_M) ? coherent : true);
 	}
 }
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index f304037d1c34..f9bc53b60f99 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -1076,7 +1076,7 @@ static void *arm_iommu_alloc_attrs(struct device *dev, size_t size,
 	pgprot_t prot = __get_dma_pgprot(attrs, PAGE_KERNEL);
 	struct page **pages;
 	void *addr = NULL;
-	int coherent_flag = dev->dma_coherent ? COHERENT : NORMAL;
+	int coherent_flag = dev_dma_coherent(dev) ? COHERENT : NORMAL;
 
 	*handle = DMA_MAPPING_ERROR;
 	size = PAGE_ALIGN(size);
@@ -1124,7 +1124,7 @@ static int arm_iommu_mmap_attrs(struct device *dev, struct vm_area_struct *vma,
 	if (vma->vm_pgoff >= nr_pages)
 		return -ENXIO;
 
-	if (!dev->dma_coherent)
+	if (!dev_dma_coherent(dev))
 		vma->vm_page_prot = __get_dma_pgprot(attrs, vma->vm_page_prot);
 
 	err = vm_map_pages(vma, pages, nr_pages);
@@ -1141,7 +1141,7 @@ static int arm_iommu_mmap_attrs(struct device *dev, struct vm_area_struct *vma,
 static void arm_iommu_free_attrs(struct device *dev, size_t size, void *cpu_addr,
 	dma_addr_t handle, unsigned long attrs)
 {
-	int coherent_flag = dev->dma_coherent ? COHERENT : NORMAL;
+	int coherent_flag = dev_dma_coherent(dev) ? COHERENT : NORMAL;
 	struct page **pages;
 	size = PAGE_ALIGN(size);
 
@@ -1202,7 +1202,7 @@ static int __map_sg_chunk(struct device *dev, struct scatterlist *sg,
 		phys_addr_t phys = page_to_phys(sg_page(s));
 		unsigned int len = PAGE_ALIGN(s->offset + s->length);
 
-		if (!dev->dma_coherent && !(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+		if (!dev_dma_coherent(dev) && !(attrs & DMA_ATTR_SKIP_CPU_SYNC))
 			arch_sync_dma_for_device(sg_phys(s), s->length, dir);
 
 		prot = __dma_info_to_prot(dir, attrs);
@@ -1304,7 +1304,7 @@ static void arm_iommu_unmap_sg(struct device *dev,
 		if (sg_dma_len(s))
 			__iommu_remove_mapping(dev, sg_dma_address(s),
 					       sg_dma_len(s));
-		if (!dev->dma_coherent && !(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+		if (!dev_dma_coherent(dev) && !(attrs & DMA_ATTR_SKIP_CPU_SYNC))
 			arch_sync_dma_for_cpu(sg_phys(s), s->length, dir);
 	}
 }
@@ -1323,7 +1323,7 @@ static void arm_iommu_sync_sg_for_cpu(struct device *dev,
 	struct scatterlist *s;
 	int i;
 
-	if (dev->dma_coherent)
+	if (dev_dma_coherent(dev))
 		return;
 
 	for_each_sg(sg, s, nents, i)
@@ -1345,7 +1345,7 @@ static void arm_iommu_sync_sg_for_device(struct device *dev,
 	struct scatterlist *s;
 	int i;
 
-	if (dev->dma_coherent)
+	if (dev_dma_coherent(dev))
 		return;
 
 	for_each_sg(sg, s, nents, i)
@@ -1371,7 +1371,7 @@ static dma_addr_t arm_iommu_map_phys(struct device *dev, phys_addr_t phys,
 	dma_addr_t dma_addr;
 	int ret, prot;
 
-	if (!dev->dma_coherent &&
+	if (!dev_dma_coherent(dev) &&
 	    !(attrs & (DMA_ATTR_SKIP_CPU_SYNC | DMA_ATTR_MMIO)))
 		arch_sync_dma_for_device(phys, size, dir);
 
@@ -1412,7 +1412,7 @@ static void arm_iommu_unmap_phys(struct device *dev, dma_addr_t handle,
 	if (!iova)
 		return;
 
-	if (!dev->dma_coherent &&
+	if (!dev_dma_coherent(dev) &&
 	    !(attrs & (DMA_ATTR_SKIP_CPU_SYNC | DMA_ATTR_MMIO))) {
 		phys_addr_t phys = iommu_iova_to_phys(mapping->domain, iova);
 
@@ -1431,7 +1431,7 @@ static void arm_iommu_sync_single_for_cpu(struct device *dev,
 	unsigned int offset = handle & ~PAGE_MASK;
 	phys_addr_t phys;
 
-	if (dev->dma_coherent || !iova)
+	if (dev_dma_coherent(dev) || !iova)
 		return;
 
 	phys = iommu_iova_to_phys(mapping->domain, iova);
@@ -1446,7 +1446,7 @@ static void arm_iommu_sync_single_for_device(struct device *dev,
 	unsigned int offset = handle & ~PAGE_MASK;
 	phys_addr_t phys;
 
-	if (dev->dma_coherent || !iova)
+	if (dev_dma_coherent(dev) || !iova)
 		return;
 
 	phys = iommu_iova_to_phys(mapping->domain, iova);
@@ -1701,13 +1701,13 @@ static void arm_teardown_iommu_dma_ops(struct device *dev) { }
 void arch_setup_dma_ops(struct device *dev, bool coherent)
 {
 	/*
-	 * Due to legacy code that sets the ->dma_coherent flag from a bus
-	 * notifier we can't just assign coherent to the ->dma_coherent flag
+	 * Due to legacy code that sets the dma_coherent flag from a bus
+	 * notifier we can't just assign coherent to the dma_coherent flag
 	 * here, but instead have to make sure we only set but never clear it
 	 * for now.
 	 */
 	if (coherent)
-		dev->dma_coherent = true;
+		dev_set_dma_coherent(dev);
 
 	/*
 	 * Don't override the dma_ops if they have already been set. Ideally
diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
index b2b5792b2caa..dc1fce939451 100644
--- a/arch/arm64/mm/dma-mapping.c
+++ b/arch/arm64/mm/dma-mapping.c
@@ -48,7 +48,7 @@ void arch_setup_dma_ops(struct device *dev, bool coherent)
 		   dev_driver_string(dev), dev_name(dev),
 		   ARCH_DMA_MINALIGN, cls);
 
-	dev->dma_coherent = coherent;
+	dev_assign_dma_coherent(dev, coherent);
 
 	xen_setup_dma_ops(dev);
 }
diff --git a/arch/mips/mm/dma-noncoherent.c b/arch/mips/mm/dma-noncoherent.c
index ab4f2a75a7d0..30ef3e247eb7 100644
--- a/arch/mips/mm/dma-noncoherent.c
+++ b/arch/mips/mm/dma-noncoherent.c
@@ -139,6 +139,6 @@ void arch_sync_dma_for_cpu(phys_addr_t paddr, size_t size,
 #ifdef CONFIG_ARCH_HAS_SETUP_DMA_OPS
 void arch_setup_dma_ops(struct device *dev, bool coherent)
 {
-	dev->dma_coherent = coherent;
+	dev_assign_dma_coherent(dev, coherent);
 }
 #endif
diff --git a/arch/riscv/mm/dma-noncoherent.c b/arch/riscv/mm/dma-noncoherent.c
index cb89d7e0ba88..a1ec2d71d1c9 100644
--- a/arch/riscv/mm/dma-noncoherent.c
+++ b/arch/riscv/mm/dma-noncoherent.c
@@ -140,7 +140,7 @@ void arch_setup_dma_ops(struct device *dev, bool coherent)
 		   "%s %s: device non-coherent but no non-coherent operations supported",
 		   dev_driver_string(dev), dev_name(dev));
 
-	dev->dma_coherent = coherent;
+	dev_assign_dma_coherent(dev, coherent);
 }
 
 void riscv_noncoherent_supported(void)
diff --git a/drivers/base/core.c b/drivers/base/core.c
index e94749092345..8a83d7c93361 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -3173,7 +3173,7 @@ void device_initialize(struct device *dev)
 #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)
-	dev->dma_coherent = dma_default_coherent;
+	dev_assign_dma_coherent(dev, dma_default_coherent);
 #endif
 	swiotlb_dev_init(dev);
 }
diff --git a/drivers/dma/ti/k3-udma-glue.c b/drivers/dma/ti/k3-udma-glue.c
index f87d244cc2d6..686dc140293e 100644
--- a/drivers/dma/ti/k3-udma-glue.c
+++ b/drivers/dma/ti/k3-udma-glue.c
@@ -312,7 +312,7 @@ k3_udma_glue_request_tx_chn_common(struct device *dev,
 
 	if (xudma_is_pktdma(tx_chn->common.udmax)) {
 		/* prepare the channel device as coherent */
-		tx_chn->common.chan_dev.dma_coherent = true;
+		dev_set_dma_coherent(&tx_chn->common.chan_dev);
 		dma_coerce_mask_and_coherent(&tx_chn->common.chan_dev,
 					     DMA_BIT_MASK(48));
 	}
@@ -1003,7 +1003,7 @@ k3_udma_glue_request_rx_chn_priv(struct device *dev, const char *name,
 
 	if (xudma_is_pktdma(rx_chn->common.udmax)) {
 		/* prepare the channel device as coherent */
-		rx_chn->common.chan_dev.dma_coherent = true;
+		dev_set_dma_coherent(&rx_chn->common.chan_dev);
 		dma_coerce_mask_and_coherent(&rx_chn->common.chan_dev,
 					     DMA_BIT_MASK(48));
 	}
@@ -1104,7 +1104,7 @@ k3_udma_glue_request_remote_rx_chn_common(struct k3_udma_glue_rx_channel *rx_chn
 
 	if (xudma_is_pktdma(rx_chn->common.udmax)) {
 		/* prepare the channel device as coherent */
-		rx_chn->common.chan_dev.dma_coherent = true;
+		dev_set_dma_coherent(&rx_chn->common.chan_dev);
 		dma_coerce_mask_and_coherent(&rx_chn->common.chan_dev,
 					     DMA_BIT_MASK(48));
 		rx_chn->single_fdq = false;
diff --git a/drivers/dma/ti/k3-udma.c b/drivers/dma/ti/k3-udma.c
index c964ebfcf3b6..1cf158eb7bdb 100644
--- a/drivers/dma/ti/k3-udma.c
+++ b/drivers/dma/ti/k3-udma.c
@@ -428,18 +428,18 @@ static void k3_configure_chan_coherency(struct dma_chan *chan, u32 asel)
 		/* No special handling for the channel */
 		chan->dev->chan_dma_dev = false;
 
-		chan_dev->dma_coherent = false;
+		dev_clear_dma_coherent(chan_dev);
 		chan_dev->dma_parms = NULL;
 	} else if (asel == 14 || asel == 15) {
 		chan->dev->chan_dma_dev = true;
 
-		chan_dev->dma_coherent = true;
+		dev_set_dma_coherent(chan_dev);
 		dma_coerce_mask_and_coherent(chan_dev, DMA_BIT_MASK(48));
 		chan_dev->dma_parms = chan_dev->parent->dma_parms;
 	} else {
 		dev_warn(chan->device->dev, "Invalid ASEL value: %u\n", asel);
 
-		chan_dev->dma_coherent = false;
+		dev_clear_dma_coherent(chan_dev);
 		chan_dev->dma_parms = NULL;
 	}
 }
diff --git a/include/linux/device.h b/include/linux/device.h
index b7a8b902efb3..5b0fb6ad4c72 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -481,6 +481,8 @@ struct device_physical_location {
  * @DEV_FLAG_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.
+ * @DEV_FLAG_DMA_COHERENT: This particular device is dma coherent, even if the
+ *		architecture supports non-coherent devices.
  */
 enum struct_device_flags {
 	DEV_FLAG_READY_TO_PROBE = 0,
@@ -489,6 +491,7 @@ enum struct_device_flags {
 	DEV_FLAG_DMA_SKIP_SYNC = 3,
 	DEV_FLAG_DMA_OPS_BYPASS = 4,
 	DEV_FLAG_STATE_SYNCED = 5,
+	DEV_FLAG_DMA_COHERENT = 6,
 
 	DEV_FLAG_COUNT
 };
@@ -572,8 +575,6 @@ enum struct_device_flags {
  * @offline:	Set after successful invocation of bus type's .offline().
  * @of_node_reused: Set if the device-tree node is shared with an ancestor
  *              device.
- * @dma_coherent: this particular device is dma coherent, even if the
- *		architecture supports non-coherent devices.
  * @flags:	DEV_FLAG_XXX flags. Use atomic bitfield operations to modify.
  *
  * At the lowest level, every device in a Linux system is represented by an
@@ -681,11 +682,6 @@ struct device {
 	bool			offline_disabled:1;
 	bool			offline:1;
 	bool			of_node_reused: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)
-	bool			dma_coherent:1;
-#endif
 
 	DECLARE_BITMAP(flags, DEV_FLAG_COUNT);
 };
@@ -718,6 +714,7 @@ __create_dev_flag_accessors(dma_iommu, DEV_FLAG_DMA_IOMMU);
 __create_dev_flag_accessors(dma_skip_sync, DEV_FLAG_DMA_SKIP_SYNC);
 __create_dev_flag_accessors(dma_ops_bypass, DEV_FLAG_DMA_OPS_BYPASS);
 __create_dev_flag_accessors(state_synced, DEV_FLAG_STATE_SYNCED);
+__create_dev_flag_accessors(dma_coherent, DEV_FLAG_DMA_COHERENT);
 
 #undef __create_dev_flag_accessors
 
diff --git a/include/linux/dma-map-ops.h b/include/linux/dma-map-ops.h
index edd7de60a957..44dd9035b4fe 100644
--- a/include/linux/dma-map-ops.h
+++ b/include/linux/dma-map-ops.h
@@ -230,7 +230,7 @@ int dma_direct_set_offset(struct device *dev, phys_addr_t cpu_start,
 extern bool dma_default_coherent;
 static inline bool dev_is_dma_coherent(struct device *dev)
 {
-	return dev->dma_coherent;
+	return dev_dma_coherent(dev);
 }
 #else
 #define dma_default_coherent true
-- 
2.53.0.1213.gd9a14994de-goog

[PATCH v5 8/9] driver core: Replace dev->of_node_reused with dev_of_node_reused()

[Douglas Anderson]

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

Cc: Johan Hovold <johan@kernel.org>
Acked-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Rafael J. Wysocki (Intel) <rafael@kernel.org>
Reviewed-by: Danilo Krummrich <dakr@kernel.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
---
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).

(no changes since v4)

Changes in v4:
- Use accessor functions for flags

Changes in v3:
- New

 drivers/base/core.c                      | 2 +-
 drivers/base/pinctrl.c                   | 2 +-
 drivers/base/platform.c                  | 2 +-
 drivers/net/pcs/pcs-xpcs-plat.c          | 2 +-
 drivers/of/device.c                      | 6 +++---
 drivers/pci/of.c                         | 2 +-
 drivers/pci/pwrctrl/core.c               | 2 +-
 drivers/regulator/bq257xx-regulator.c    | 2 +-
 drivers/regulator/rk808-regulator.c      | 2 +-
 drivers/tty/serial/serial_base_bus.c     | 2 +-
 drivers/usb/gadget/udc/aspeed-vhub/dev.c | 2 +-
 include/linux/device.h                   | 7 ++++---
 12 files changed, 17 insertions(+), 16 deletions(-)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 8a83d7c93361..30825bf83234 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -5283,7 +5283,7 @@ void device_set_of_node_from_dev(struct device *dev, const struct device *dev2)
 {
 	of_node_put(dev->of_node);
 	dev->of_node = of_node_get(dev2->of_node);
-	dev->of_node_reused = true;
+	dev_set_of_node_reused(dev);
 }
 EXPORT_SYMBOL_GPL(device_set_of_node_from_dev);
 
diff --git a/drivers/base/pinctrl.c b/drivers/base/pinctrl.c
index 6e250272c843..0bbc83231234 100644
--- a/drivers/base/pinctrl.c
+++ b/drivers/base/pinctrl.c
@@ -24,7 +24,7 @@ int pinctrl_bind_pins(struct device *dev)
 {
 	int ret;
 
-	if (dev->of_node_reused)
+	if (dev_of_node_reused(dev))
 		return 0;
 
 	dev->pins = devm_kzalloc(dev, sizeof(*(dev->pins)), GFP_KERNEL);
diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index d44591d52e36..199e6fb25770 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -856,7 +856,7 @@ struct platform_device *platform_device_register_full(
 	pdev->dev.parent = pdevinfo->parent;
 	pdev->dev.fwnode = pdevinfo->fwnode;
 	pdev->dev.of_node = of_node_get(to_of_node(pdev->dev.fwnode));
-	pdev->dev.of_node_reused = pdevinfo->of_node_reused;
+	dev_assign_of_node_reused(&pdev->dev, pdevinfo->of_node_reused);
 
 	if (pdevinfo->dma_mask) {
 		pdev->platform_dma_mask = pdevinfo->dma_mask;
diff --git a/drivers/net/pcs/pcs-xpcs-plat.c b/drivers/net/pcs/pcs-xpcs-plat.c
index b8c48f9effbf..f4b1b8246ce9 100644
--- a/drivers/net/pcs/pcs-xpcs-plat.c
+++ b/drivers/net/pcs/pcs-xpcs-plat.c
@@ -349,7 +349,7 @@ static int xpcs_plat_init_dev(struct dw_xpcs_plat *pxpcs)
 	 * up later. Make sure DD-core is aware of the OF-node being re-used.
 	 */
 	device_set_node(&mdiodev->dev, fwnode_handle_get(dev_fwnode(dev)));
-	mdiodev->dev.of_node_reused = true;
+	dev_set_of_node_reused(&mdiodev->dev);
 
 	/* Pass the data further so the DW XPCS driver core could use it */
 	mdiodev->dev.platform_data = (void *)device_get_match_data(dev);
diff --git a/drivers/of/device.c b/drivers/of/device.c
index f7e75e527667..be4e1584e0af 100644
--- a/drivers/of/device.c
+++ b/drivers/of/device.c
@@ -26,7 +26,7 @@
 const struct of_device_id *of_match_device(const struct of_device_id *matches,
 					   const struct device *dev)
 {
-	if (!matches || !dev->of_node || dev->of_node_reused)
+	if (!matches || !dev->of_node || dev_of_node_reused(dev))
 		return NULL;
 	return of_match_node(matches, dev->of_node);
 }
@@ -192,7 +192,7 @@ ssize_t of_device_modalias(struct device *dev, char *str, ssize_t len)
 {
 	ssize_t sl;
 
-	if (!dev || !dev->of_node || dev->of_node_reused)
+	if (!dev || !dev->of_node || dev_of_node_reused(dev))
 		return -ENODEV;
 
 	sl = of_modalias(dev->of_node, str, len - 2);
@@ -254,7 +254,7 @@ int of_device_uevent_modalias(const struct device *dev, struct kobj_uevent_env *
 {
 	int sl;
 
-	if ((!dev) || (!dev->of_node) || dev->of_node_reused)
+	if ((!dev) || (!dev->of_node) || dev_of_node_reused(dev))
 		return -ENODEV;
 
 	/* Devicetree modalias is tricky, we add it in 2 steps */
diff --git a/drivers/pci/of.c b/drivers/pci/of.c
index 9f8eb5df279e..1f9b669abdb0 100644
--- a/drivers/pci/of.c
+++ b/drivers/pci/of.c
@@ -38,7 +38,7 @@ int pci_set_of_node(struct pci_dev *dev)
 	struct device *pdev __free(put_device) =
 		bus_find_device_by_of_node(&platform_bus_type, node);
 	if (pdev)
-		dev->bus->dev.of_node_reused = true;
+		dev_set_of_node_reused(&dev->bus->dev);
 
 	device_set_node(&dev->dev, of_fwnode_handle(no_free_ptr(node)));
 	return 0;
diff --git a/drivers/pci/pwrctrl/core.c b/drivers/pci/pwrctrl/core.c
index 7754baed67f2..72963a92362a 100644
--- a/drivers/pci/pwrctrl/core.c
+++ b/drivers/pci/pwrctrl/core.c
@@ -39,7 +39,7 @@ static int pci_pwrctrl_notify(struct notifier_block *nb, unsigned long action,
 		 * If we got here then the PCI device is the second after the
 		 * power control platform device. Mark its OF node as reused.
 		 */
-		dev->of_node_reused = true;
+		dev_set_of_node_reused(dev);
 		break;
 	}
 
diff --git a/drivers/regulator/bq257xx-regulator.c b/drivers/regulator/bq257xx-regulator.c
index dab8f1ab4450..40e0f1a7ae81 100644
--- a/drivers/regulator/bq257xx-regulator.c
+++ b/drivers/regulator/bq257xx-regulator.c
@@ -143,7 +143,7 @@ static int bq257xx_regulator_probe(struct platform_device *pdev)
 	struct regulator_config cfg = {};
 
 	pdev->dev.of_node = pdev->dev.parent->of_node;
-	pdev->dev.of_node_reused = true;
+	dev_set_of_node_reused(&pdev->dev);
 
 	pdata = devm_kzalloc(&pdev->dev, sizeof(struct bq257xx_reg_data), GFP_KERNEL);
 	if (!pdata)
diff --git a/drivers/regulator/rk808-regulator.c b/drivers/regulator/rk808-regulator.c
index e66408f23bb6..8297d31cde9f 100644
--- a/drivers/regulator/rk808-regulator.c
+++ b/drivers/regulator/rk808-regulator.c
@@ -2115,7 +2115,7 @@ static int rk808_regulator_probe(struct platform_device *pdev)
 	int ret, i, nregulators;
 
 	pdev->dev.of_node = pdev->dev.parent->of_node;
-	pdev->dev.of_node_reused = true;
+	dev_set_of_node_reused(&pdev->dev);
 
 	regmap = dev_get_regmap(pdev->dev.parent, NULL);
 	if (!regmap)
diff --git a/drivers/tty/serial/serial_base_bus.c b/drivers/tty/serial/serial_base_bus.c
index a12935f6b992..5f23284a8778 100644
--- a/drivers/tty/serial/serial_base_bus.c
+++ b/drivers/tty/serial/serial_base_bus.c
@@ -74,7 +74,7 @@ static int serial_base_device_init(struct uart_port *port,
 	dev->parent = parent_dev;
 	dev->bus = &serial_base_bus_type;
 	dev->release = release;
-	dev->of_node_reused = true;
+	dev_set_of_node_reused(dev);
 
 	device_set_node(dev, fwnode_handle_get(dev_fwnode(parent_dev)));
 
diff --git a/drivers/usb/gadget/udc/aspeed-vhub/dev.c b/drivers/usb/gadget/udc/aspeed-vhub/dev.c
index 2ecd049dacc2..8b9449d16324 100644
--- a/drivers/usb/gadget/udc/aspeed-vhub/dev.c
+++ b/drivers/usb/gadget/udc/aspeed-vhub/dev.c
@@ -593,7 +593,7 @@ int ast_vhub_init_dev(struct ast_vhub *vhub, unsigned int idx)
 		d->gadget.max_speed = USB_SPEED_HIGH;
 	d->gadget.speed = USB_SPEED_UNKNOWN;
 	d->gadget.dev.of_node = vhub->pdev->dev.of_node;
-	d->gadget.dev.of_node_reused = true;
+	dev_set_of_node_reused(&d->gadget.dev);
 
 	rc = usb_add_gadget_udc(d->port_dev, &d->gadget);
 	if (rc != 0)
diff --git a/include/linux/device.h b/include/linux/device.h
index 5b0fb6ad4c72..a79865a212e9 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -483,6 +483,8 @@ struct device_physical_location {
  *		driver/bus sync_state() callback.
  * @DEV_FLAG_DMA_COHERENT: This particular device is dma coherent, even if the
  *		architecture supports non-coherent devices.
+ * @DEV_FLAG_OF_NODE_REUSED: Set if the device-tree node is shared with an
+ *		ancestor device.
  */
 enum struct_device_flags {
 	DEV_FLAG_READY_TO_PROBE = 0,
@@ -492,6 +494,7 @@ enum struct_device_flags {
 	DEV_FLAG_DMA_OPS_BYPASS = 4,
 	DEV_FLAG_STATE_SYNCED = 5,
 	DEV_FLAG_DMA_COHERENT = 6,
+	DEV_FLAG_OF_NODE_REUSED = 7,
 
 	DEV_FLAG_COUNT
 };
@@ -573,8 +576,6 @@ enum struct_device_flags {
  *
  * @offline_disabled: If set, the device is permanently online.
  * @offline:	Set after successful invocation of bus type's .offline().
- * @of_node_reused: Set if the device-tree node is shared with an ancestor
- *              device.
  * @flags:	DEV_FLAG_XXX flags. Use atomic bitfield operations to modify.
  *
  * At the lowest level, every device in a Linux system is represented by an
@@ -681,7 +682,6 @@ struct device {
 
 	bool			offline_disabled:1;
 	bool			offline:1;
-	bool			of_node_reused:1;
 
 	DECLARE_BITMAP(flags, DEV_FLAG_COUNT);
 };
@@ -715,6 +715,7 @@ __create_dev_flag_accessors(dma_skip_sync, DEV_FLAG_DMA_SKIP_SYNC);
 __create_dev_flag_accessors(dma_ops_bypass, DEV_FLAG_DMA_OPS_BYPASS);
 __create_dev_flag_accessors(state_synced, DEV_FLAG_STATE_SYNCED);
 __create_dev_flag_accessors(dma_coherent, DEV_FLAG_DMA_COHERENT);
+__create_dev_flag_accessors(of_node_reused, DEV_FLAG_OF_NODE_REUSED);
 
 #undef __create_dev_flag_accessors
 
-- 
2.53.0.1213.gd9a14994de-goog

Re: [PATCH v5 8/9] driver core: Replace dev->of_node_reused with dev_of_node_reused()

[Manivannan Sadhasivam]

On Mon, Apr 06, 2026 at 04:23:01PM -0700, Douglas Anderson wrote:
> In C, bitfields are not necessarily safe to modify from multiple
> threads without locking. Switch "of_node_reused" over to the "flags"
> field so modifications are safe.
> 
> Cc: Johan Hovold <johan@kernel.org>
> Acked-by: Mark Brown <broonie@kernel.org>
> Reviewed-by: Rafael J. Wysocki (Intel) <rafael@kernel.org>
> Reviewed-by: Danilo Krummrich <dakr@kernel.org>
> Signed-off-by: Douglas Anderson <dianders@chromium.org>

Acked-by: Manivannan Sadhasivam <mani@kernel.org> # PCI_PWRCTRL

- Mani

> ---
> 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).
> 
> (no changes since v4)
> 
> Changes in v4:
> - Use accessor functions for flags
> 
> Changes in v3:
> - New
> 
>  drivers/base/core.c                      | 2 +-
>  drivers/base/pinctrl.c                   | 2 +-
>  drivers/base/platform.c                  | 2 +-
>  drivers/net/pcs/pcs-xpcs-plat.c          | 2 +-
>  drivers/of/device.c                      | 6 +++---
>  drivers/pci/of.c                         | 2 +-
>  drivers/pci/pwrctrl/core.c               | 2 +-
>  drivers/regulator/bq257xx-regulator.c    | 2 +-
>  drivers/regulator/rk808-regulator.c      | 2 +-
>  drivers/tty/serial/serial_base_bus.c     | 2 +-
>  drivers/usb/gadget/udc/aspeed-vhub/dev.c | 2 +-
>  include/linux/device.h                   | 7 ++++---
>  12 files changed, 17 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index 8a83d7c93361..30825bf83234 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -5283,7 +5283,7 @@ void device_set_of_node_from_dev(struct device *dev, const struct device *dev2)
>  {
>  	of_node_put(dev->of_node);
>  	dev->of_node = of_node_get(dev2->of_node);
> -	dev->of_node_reused = true;
> +	dev_set_of_node_reused(dev);
>  }
>  EXPORT_SYMBOL_GPL(device_set_of_node_from_dev);
>  
> diff --git a/drivers/base/pinctrl.c b/drivers/base/pinctrl.c
> index 6e250272c843..0bbc83231234 100644
> --- a/drivers/base/pinctrl.c
> +++ b/drivers/base/pinctrl.c
> @@ -24,7 +24,7 @@ int pinctrl_bind_pins(struct device *dev)
>  {
>  	int ret;
>  
> -	if (dev->of_node_reused)
> +	if (dev_of_node_reused(dev))
>  		return 0;
>  
>  	dev->pins = devm_kzalloc(dev, sizeof(*(dev->pins)), GFP_KERNEL);
> diff --git a/drivers/base/platform.c b/drivers/base/platform.c
> index d44591d52e36..199e6fb25770 100644
> --- a/drivers/base/platform.c
> +++ b/drivers/base/platform.c
> @@ -856,7 +856,7 @@ struct platform_device *platform_device_register_full(
>  	pdev->dev.parent = pdevinfo->parent;
>  	pdev->dev.fwnode = pdevinfo->fwnode;
>  	pdev->dev.of_node = of_node_get(to_of_node(pdev->dev.fwnode));
> -	pdev->dev.of_node_reused = pdevinfo->of_node_reused;
> +	dev_assign_of_node_reused(&pdev->dev, pdevinfo->of_node_reused);
>  
>  	if (pdevinfo->dma_mask) {
>  		pdev->platform_dma_mask = pdevinfo->dma_mask;
> diff --git a/drivers/net/pcs/pcs-xpcs-plat.c b/drivers/net/pcs/pcs-xpcs-plat.c
> index b8c48f9effbf..f4b1b8246ce9 100644
> --- a/drivers/net/pcs/pcs-xpcs-plat.c
> +++ b/drivers/net/pcs/pcs-xpcs-plat.c
> @@ -349,7 +349,7 @@ static int xpcs_plat_init_dev(struct dw_xpcs_plat *pxpcs)
>  	 * up later. Make sure DD-core is aware of the OF-node being re-used.
>  	 */
>  	device_set_node(&mdiodev->dev, fwnode_handle_get(dev_fwnode(dev)));
> -	mdiodev->dev.of_node_reused = true;
> +	dev_set_of_node_reused(&mdiodev->dev);
>  
>  	/* Pass the data further so the DW XPCS driver core could use it */
>  	mdiodev->dev.platform_data = (void *)device_get_match_data(dev);
> diff --git a/drivers/of/device.c b/drivers/of/device.c
> index f7e75e527667..be4e1584e0af 100644
> --- a/drivers/of/device.c
> +++ b/drivers/of/device.c
> @@ -26,7 +26,7 @@
>  const struct of_device_id *of_match_device(const struct of_device_id *matches,
>  					   const struct device *dev)
>  {
> -	if (!matches || !dev->of_node || dev->of_node_reused)
> +	if (!matches || !dev->of_node || dev_of_node_reused(dev))
>  		return NULL;
>  	return of_match_node(matches, dev->of_node);
>  }
> @@ -192,7 +192,7 @@ ssize_t of_device_modalias(struct device *dev, char *str, ssize_t len)
>  {
>  	ssize_t sl;
>  
> -	if (!dev || !dev->of_node || dev->of_node_reused)
> +	if (!dev || !dev->of_node || dev_of_node_reused(dev))
>  		return -ENODEV;
>  
>  	sl = of_modalias(dev->of_node, str, len - 2);
> @@ -254,7 +254,7 @@ int of_device_uevent_modalias(const struct device *dev, struct kobj_uevent_env *
>  {
>  	int sl;
>  
> -	if ((!dev) || (!dev->of_node) || dev->of_node_reused)
> +	if ((!dev) || (!dev->of_node) || dev_of_node_reused(dev))
>  		return -ENODEV;
>  
>  	/* Devicetree modalias is tricky, we add it in 2 steps */
> diff --git a/drivers/pci/of.c b/drivers/pci/of.c
> index 9f8eb5df279e..1f9b669abdb0 100644
> --- a/drivers/pci/of.c
> +++ b/drivers/pci/of.c
> @@ -38,7 +38,7 @@ int pci_set_of_node(struct pci_dev *dev)
>  	struct device *pdev __free(put_device) =
>  		bus_find_device_by_of_node(&platform_bus_type, node);
>  	if (pdev)
> -		dev->bus->dev.of_node_reused = true;
> +		dev_set_of_node_reused(&dev->bus->dev);
>  
>  	device_set_node(&dev->dev, of_fwnode_handle(no_free_ptr(node)));
>  	return 0;
> diff --git a/drivers/pci/pwrctrl/core.c b/drivers/pci/pwrctrl/core.c
> index 7754baed67f2..72963a92362a 100644
> --- a/drivers/pci/pwrctrl/core.c
> +++ b/drivers/pci/pwrctrl/core.c
> @@ -39,7 +39,7 @@ static int pci_pwrctrl_notify(struct notifier_block *nb, unsigned long action,
>  		 * If we got here then the PCI device is the second after the
>  		 * power control platform device. Mark its OF node as reused.
>  		 */
> -		dev->of_node_reused = true;
> +		dev_set_of_node_reused(dev);
>  		break;
>  	}
>  
> diff --git a/drivers/regulator/bq257xx-regulator.c b/drivers/regulator/bq257xx-regulator.c
> index dab8f1ab4450..40e0f1a7ae81 100644
> --- a/drivers/regulator/bq257xx-regulator.c
> +++ b/drivers/regulator/bq257xx-regulator.c
> @@ -143,7 +143,7 @@ static int bq257xx_regulator_probe(struct platform_device *pdev)
>  	struct regulator_config cfg = {};
>  
>  	pdev->dev.of_node = pdev->dev.parent->of_node;
> -	pdev->dev.of_node_reused = true;
> +	dev_set_of_node_reused(&pdev->dev);
>  
>  	pdata = devm_kzalloc(&pdev->dev, sizeof(struct bq257xx_reg_data), GFP_KERNEL);
>  	if (!pdata)
> diff --git a/drivers/regulator/rk808-regulator.c b/drivers/regulator/rk808-regulator.c
> index e66408f23bb6..8297d31cde9f 100644
> --- a/drivers/regulator/rk808-regulator.c
> +++ b/drivers/regulator/rk808-regulator.c
> @@ -2115,7 +2115,7 @@ static int rk808_regulator_probe(struct platform_device *pdev)
>  	int ret, i, nregulators;
>  
>  	pdev->dev.of_node = pdev->dev.parent->of_node;
> -	pdev->dev.of_node_reused = true;
> +	dev_set_of_node_reused(&pdev->dev);
>  
>  	regmap = dev_get_regmap(pdev->dev.parent, NULL);
>  	if (!regmap)
> diff --git a/drivers/tty/serial/serial_base_bus.c b/drivers/tty/serial/serial_base_bus.c
> index a12935f6b992..5f23284a8778 100644
> --- a/drivers/tty/serial/serial_base_bus.c
> +++ b/drivers/tty/serial/serial_base_bus.c
> @@ -74,7 +74,7 @@ static int serial_base_device_init(struct uart_port *port,
>  	dev->parent = parent_dev;
>  	dev->bus = &serial_base_bus_type;
>  	dev->release = release;
> -	dev->of_node_reused = true;
> +	dev_set_of_node_reused(dev);
>  
>  	device_set_node(dev, fwnode_handle_get(dev_fwnode(parent_dev)));
>  
> diff --git a/drivers/usb/gadget/udc/aspeed-vhub/dev.c b/drivers/usb/gadget/udc/aspeed-vhub/dev.c
> index 2ecd049dacc2..8b9449d16324 100644
> --- a/drivers/usb/gadget/udc/aspeed-vhub/dev.c
> +++ b/drivers/usb/gadget/udc/aspeed-vhub/dev.c
> @@ -593,7 +593,7 @@ int ast_vhub_init_dev(struct ast_vhub *vhub, unsigned int idx)
>  		d->gadget.max_speed = USB_SPEED_HIGH;
>  	d->gadget.speed = USB_SPEED_UNKNOWN;
>  	d->gadget.dev.of_node = vhub->pdev->dev.of_node;
> -	d->gadget.dev.of_node_reused = true;
> +	dev_set_of_node_reused(&d->gadget.dev);
>  
>  	rc = usb_add_gadget_udc(d->port_dev, &d->gadget);
>  	if (rc != 0)
> diff --git a/include/linux/device.h b/include/linux/device.h
> index 5b0fb6ad4c72..a79865a212e9 100644
> --- a/include/linux/device.h
> +++ b/include/linux/device.h
> @@ -483,6 +483,8 @@ struct device_physical_location {
>   *		driver/bus sync_state() callback.
>   * @DEV_FLAG_DMA_COHERENT: This particular device is dma coherent, even if the
>   *		architecture supports non-coherent devices.
> + * @DEV_FLAG_OF_NODE_REUSED: Set if the device-tree node is shared with an
> + *		ancestor device.
>   */
>  enum struct_device_flags {
>  	DEV_FLAG_READY_TO_PROBE = 0,
> @@ -492,6 +494,7 @@ enum struct_device_flags {
>  	DEV_FLAG_DMA_OPS_BYPASS = 4,
>  	DEV_FLAG_STATE_SYNCED = 5,
>  	DEV_FLAG_DMA_COHERENT = 6,
> +	DEV_FLAG_OF_NODE_REUSED = 7,
>  
>  	DEV_FLAG_COUNT
>  };
> @@ -573,8 +576,6 @@ enum struct_device_flags {
>   *
>   * @offline_disabled: If set, the device is permanently online.
>   * @offline:	Set after successful invocation of bus type's .offline().
> - * @of_node_reused: Set if the device-tree node is shared with an ancestor
> - *              device.
>   * @flags:	DEV_FLAG_XXX flags. Use atomic bitfield operations to modify.
>   *
>   * At the lowest level, every device in a Linux system is represented by an
> @@ -681,7 +682,6 @@ struct device {
>  
>  	bool			offline_disabled:1;
>  	bool			offline:1;
> -	bool			of_node_reused:1;
>  
>  	DECLARE_BITMAP(flags, DEV_FLAG_COUNT);
>  };
> @@ -715,6 +715,7 @@ __create_dev_flag_accessors(dma_skip_sync, DEV_FLAG_DMA_SKIP_SYNC);
>  __create_dev_flag_accessors(dma_ops_bypass, DEV_FLAG_DMA_OPS_BYPASS);
>  __create_dev_flag_accessors(state_synced, DEV_FLAG_STATE_SYNCED);
>  __create_dev_flag_accessors(dma_coherent, DEV_FLAG_DMA_COHERENT);
> +__create_dev_flag_accessors(of_node_reused, DEV_FLAG_OF_NODE_REUSED);
>  
>  #undef __create_dev_flag_accessors
>  
> -- 
> 2.53.0.1213.gd9a14994de-goog
> 

-- 
மணிவண்ணன் சதாசிவம்

Re: [PATCH v5 8/9] driver core: Replace dev->of_node_reused with dev_of_node_reused()

[Johan Hovold]

On Mon, Apr 06, 2026 at 04:23:01PM -0700, Doug Anderson wrote:
> In C, bitfields are not necessarily safe to modify from multiple
> threads without locking. Switch "of_node_reused" over to the "flags"
> field so modifications are safe.

This flag is only set before registering a device with driver core so
there is no issue using the existing bitfield here (with the caveat that
PCI pwrctrl may have gotten that wrong). I haven't checked the other
flags, but I assume most of them work the same way.

But apart from the commit message being misleading, switching to using
atomic ops and accessors for consistency is fine.

> Cc: Johan Hovold <johan@kernel.org>
> Acked-by: Mark Brown <broonie@kernel.org>
> Reviewed-by: Rafael J. Wysocki (Intel) <rafael@kernel.org>
> Reviewed-by: Danilo Krummrich <dakr@kernel.org>
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> ---
> 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).
 
> diff --git a/drivers/regulator/bq257xx-regulator.c b/drivers/regulator/bq257xx-regulator.c
> index dab8f1ab4450..40e0f1a7ae81 100644
> --- a/drivers/regulator/bq257xx-regulator.c
> +++ b/drivers/regulator/bq257xx-regulator.c
> @@ -143,7 +143,7 @@ static int bq257xx_regulator_probe(struct platform_device *pdev)
>  	struct regulator_config cfg = {};
>  
>  	pdev->dev.of_node = pdev->dev.parent->of_node;
> -	pdev->dev.of_node_reused = true;
> +	dev_set_of_node_reused(&pdev->dev);
>  
>  	pdata = devm_kzalloc(&pdev->dev, sizeof(struct bq257xx_reg_data), GFP_KERNEL);
>  	if (!pdata)
> diff --git a/drivers/regulator/rk808-regulator.c b/drivers/regulator/rk808-regulator.c
> index e66408f23bb6..8297d31cde9f 100644
> --- a/drivers/regulator/rk808-regulator.c
> +++ b/drivers/regulator/rk808-regulator.c
> @@ -2115,7 +2115,7 @@ static int rk808_regulator_probe(struct platform_device *pdev)
>  	int ret, i, nregulators;
>  
>  	pdev->dev.of_node = pdev->dev.parent->of_node;
> -	pdev->dev.of_node_reused = true;
> +	dev_set_of_node_reused(&pdev->dev);
>  
>  	regmap = dev_get_regmap(pdev->dev.parent, NULL);
>  	if (!regmap)

These two uses are broken currently though and should be using
device_set_of_node_from_dev() so that an extra reference is taken to
balance the one dropped by the platform bus code.

I'll send two fixes to Mark, any merge conflict should be trivial to
fixup.

Reviewed-by: Johan Hovold <johan@kernel.org>

Johan

[PATCH v5 9/9] driver core: Replace dev->offline + ->offline_disabled with accessors

[Douglas Anderson]

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

Cc: Rafael J. Wysocki <rafael@kernel.org>
Acked-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Rafael J. Wysocki (Intel) <rafael@kernel.org>
Reviewed-by: Danilo Krummrich <dakr@kernel.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
---
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).

(no changes since v4)

Changes in v4:
- Use accessor functions for flags

Changes in v3:
- New

 arch/arm64/kernel/cpufeature.c                 |  2 +-
 .../powerpc/platforms/pseries/hotplug-memory.c |  4 ++--
 drivers/acpi/scan.c                            |  2 +-
 drivers/base/core.c                            | 18 +++++++++---------
 drivers/base/cpu.c                             |  4 ++--
 drivers/base/memory.c                          |  2 +-
 include/linux/device.h                         | 12 ++++++------
 kernel/cpu.c                                   |  4 ++--
 8 files changed, 24 insertions(+), 24 deletions(-)

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 32c2dbcc0c64..c832aa565dc2 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -4042,7 +4042,7 @@ static int enable_mismatched_32bit_el0(unsigned int cpu)
 	 */
 	lucky_winner = cpu_32bit ? cpu : cpumask_any_and(cpu_32bit_el0_mask,
 							 cpu_active_mask);
-	get_cpu_device(lucky_winner)->offline_disabled = true;
+	dev_set_offline_disabled(get_cpu_device(lucky_winner));
 	setup_elf_hwcaps(compat_elf_hwcaps);
 	elf_hwcap_fixup();
 	pr_info("Asymmetric 32-bit EL0 support detected on CPU %u; CPU hot-unplug disabled on CPU %u\n",
diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c b/arch/powerpc/platforms/pseries/hotplug-memory.c
index b2f14db59034..75f85a5da981 100644
--- a/arch/powerpc/platforms/pseries/hotplug-memory.c
+++ b/arch/powerpc/platforms/pseries/hotplug-memory.c
@@ -213,9 +213,9 @@ static int dlpar_change_lmb_state(struct drmem_lmb *lmb, bool online)
 		return -EINVAL;
 	}
 
-	if (online && mem_block->dev.offline)
+	if (online && dev_offline(&mem_block->dev))
 		rc = device_online(&mem_block->dev);
-	else if (!online && !mem_block->dev.offline)
+	else if (!online && !dev_offline(&mem_block->dev))
 		rc = device_offline(&mem_block->dev);
 	else
 		rc = 0;
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index e8cdbdb46fdb..1353adbcc234 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -122,7 +122,7 @@ bool acpi_scan_is_offline(struct acpi_device *adev, bool uevent)
 	mutex_lock_nested(&adev->physical_node_lock, SINGLE_DEPTH_NESTING);
 
 	list_for_each_entry(pn, &adev->physical_node_list, node)
-		if (device_supports_offline(pn->dev) && !pn->dev->offline) {
+		if (device_supports_offline(pn->dev) && !dev_offline(pn->dev)) {
 			if (uevent)
 				kobject_uevent_env(&pn->dev->kobj, KOBJ_CHANGE, envp);
 
diff --git a/drivers/base/core.c b/drivers/base/core.c
index 30825bf83234..4f293aed879a 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -2788,7 +2788,7 @@ static ssize_t online_show(struct device *dev, struct device_attribute *attr,
 	bool val;
 
 	device_lock(dev);
-	val = !dev->offline;
+	val = !dev_offline(dev);
 	device_unlock(dev);
 	return sysfs_emit(buf, "%u\n", val);
 }
@@ -2913,7 +2913,7 @@ static int device_add_attrs(struct device *dev)
 	if (error)
 		goto err_remove_type_groups;
 
-	if (device_supports_offline(dev) && !dev->offline_disabled) {
+	if (device_supports_offline(dev) && !dev_offline_disabled(dev)) {
 		error = device_create_file(dev, &dev_attr_online);
 		if (error)
 			goto err_remove_dev_groups;
@@ -4180,7 +4180,7 @@ static int device_check_offline(struct device *dev, void *not_used)
 	if (ret)
 		return ret;
 
-	return device_supports_offline(dev) && !dev->offline ? -EBUSY : 0;
+	return device_supports_offline(dev) && !dev_offline(dev) ? -EBUSY : 0;
 }
 
 /**
@@ -4198,7 +4198,7 @@ int device_offline(struct device *dev)
 {
 	int ret;
 
-	if (dev->offline_disabled)
+	if (dev_offline_disabled(dev))
 		return -EPERM;
 
 	ret = device_for_each_child(dev, NULL, device_check_offline);
@@ -4207,13 +4207,13 @@ int device_offline(struct device *dev)
 
 	device_lock(dev);
 	if (device_supports_offline(dev)) {
-		if (dev->offline) {
+		if (dev_offline(dev)) {
 			ret = 1;
 		} else {
 			ret = dev->bus->offline(dev);
 			if (!ret) {
 				kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
-				dev->offline = true;
+				dev_set_offline(dev);
 			}
 		}
 	}
@@ -4238,11 +4238,11 @@ int device_online(struct device *dev)
 
 	device_lock(dev);
 	if (device_supports_offline(dev)) {
-		if (dev->offline) {
+		if (dev_offline(dev)) {
 			ret = dev->bus->online(dev);
 			if (!ret) {
 				kobject_uevent(&dev->kobj, KOBJ_ONLINE);
-				dev->offline = false;
+				dev_clear_offline(dev);
 			}
 		} else {
 			ret = 1;
@@ -4716,7 +4716,7 @@ static int device_attrs_change_owner(struct device *dev, kuid_t kuid,
 	if (error)
 		return error;
 
-	if (device_supports_offline(dev) && !dev->offline_disabled) {
+	if (device_supports_offline(dev) && !dev_offline_disabled(dev)) {
 		/* Change online device attributes of @dev to @kuid/@kgid. */
 		error = sysfs_file_change_owner(kobj, dev_attr_online.attr.name,
 						kuid, kgid);
diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index 875abdc9942e..19d288a3c80c 100644
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -422,8 +422,8 @@ int register_cpu(struct cpu *cpu, int num)
 	cpu->dev.id = num;
 	cpu->dev.bus = &cpu_subsys;
 	cpu->dev.release = cpu_device_release;
-	cpu->dev.offline_disabled = !cpu->hotpluggable;
-	cpu->dev.offline = !cpu_online(num);
+	dev_assign_offline_disabled(&cpu->dev, !cpu->hotpluggable);
+	dev_assign_offline(&cpu->dev, !cpu_online(num));
 	cpu->dev.of_node = of_get_cpu_node(num, NULL);
 	cpu->dev.groups = common_cpu_attr_groups;
 	if (cpu->hotpluggable)
diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index a3091924918b..5005654f44fa 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -697,7 +697,7 @@ static int __add_memory_block(struct memory_block *memory)
 	memory->dev.id = memory->start_section_nr / sections_per_block;
 	memory->dev.release = memory_block_release;
 	memory->dev.groups = memory_memblk_attr_groups;
-	memory->dev.offline = memory->state == MEM_OFFLINE;
+	dev_assign_offline(&memory->dev, memory->state == MEM_OFFLINE);
 
 	ret = device_register(&memory->dev);
 	if (ret) {
diff --git a/include/linux/device.h b/include/linux/device.h
index a79865a212e9..d695f7537112 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -485,6 +485,8 @@ struct device_physical_location {
  *		architecture supports non-coherent devices.
  * @DEV_FLAG_OF_NODE_REUSED: Set if the device-tree node is shared with an
  *		ancestor device.
+ * @DEV_FLAG_OFFLINE_DISABLED: If set, the device is permanently online.
+ * @DEV_FLAG_OFFLINE: Set after successful invocation of bus type's .offline().
  */
 enum struct_device_flags {
 	DEV_FLAG_READY_TO_PROBE = 0,
@@ -495,6 +497,8 @@ enum struct_device_flags {
 	DEV_FLAG_STATE_SYNCED = 5,
 	DEV_FLAG_DMA_COHERENT = 6,
 	DEV_FLAG_OF_NODE_REUSED = 7,
+	DEV_FLAG_OFFLINE_DISABLED = 8,
+	DEV_FLAG_OFFLINE = 9,
 
 	DEV_FLAG_COUNT
 };
@@ -573,9 +577,6 @@ enum struct_device_flags {
  * @removable:  Whether the device can be removed from the system. This
  *              should be set by the subsystem / bus driver that discovered
  *              the device.
- *
- * @offline_disabled: If set, the device is permanently online.
- * @offline:	Set after successful invocation of bus type's .offline().
  * @flags:	DEV_FLAG_XXX flags. Use atomic bitfield operations to modify.
  *
  * At the lowest level, every device in a Linux system is represented by an
@@ -680,9 +681,6 @@ struct device {
 
 	enum device_removable	removable;
 
-	bool			offline_disabled:1;
-	bool			offline:1;
-
 	DECLARE_BITMAP(flags, DEV_FLAG_COUNT);
 };
 
@@ -716,6 +714,8 @@ __create_dev_flag_accessors(dma_ops_bypass, DEV_FLAG_DMA_OPS_BYPASS);
 __create_dev_flag_accessors(state_synced, DEV_FLAG_STATE_SYNCED);
 __create_dev_flag_accessors(dma_coherent, DEV_FLAG_DMA_COHERENT);
 __create_dev_flag_accessors(of_node_reused, DEV_FLAG_OF_NODE_REUSED);
+__create_dev_flag_accessors(offline_disabled, DEV_FLAG_OFFLINE_DISABLED);
+__create_dev_flag_accessors(offline, DEV_FLAG_OFFLINE);
 
 #undef __create_dev_flag_accessors
 
diff --git a/kernel/cpu.c b/kernel/cpu.c
index bc4f7a9ba64e..f975bb34915b 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -2639,7 +2639,7 @@ static void cpuhp_offline_cpu_device(unsigned int cpu)
 {
 	struct device *dev = get_cpu_device(cpu);
 
-	dev->offline = true;
+	dev_set_offline(dev);
 	/* Tell user space about the state change */
 	kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
 }
@@ -2648,7 +2648,7 @@ static void cpuhp_online_cpu_device(unsigned int cpu)
 {
 	struct device *dev = get_cpu_device(cpu);
 
-	dev->offline = false;
+	dev_clear_offline(dev);
 	/* Tell user space about the state change */
 	kobject_uevent(&dev->kobj, KOBJ_ONLINE);
 }
-- 
2.53.0.1213.gd9a14994de-goog

Re: [PATCH v5 0/9] driver core: Fix some race conditions

[Marek Szyprowski]

On 07.04.2026 01:22, Douglas Anderson wrote:
> The main goal of this series is to fix the observed bug talked about
> in the first patch ("driver core: Don't let a device probe until it's
> ready"). That patch fixes a problem that has been observed in the real
> world and could land even if the rest of the patches are found
> unacceptable or need to be spun.
>
> That said, during patch review Danilo correctly pointed out that many
> of the bitfield accesses in "struct device" are unsafe. I added a
> bunch of patches in the series to address each one.
>
> Danilo said he's most worried about "can_match", so I put that one
> first. After that, I tried to transition bitfields to flags in reverse
> order to when the bitfield was added.
>
> Even if transitioning from bitfields to flags isn't truly needed for
> correctness, it seems silly (and wasteful of space in struct device)
> to have some in bitfields and some as flags. Thus I didn't spend time
> for each bitfield showing that it's truly needed for correctness.
>
> Transition was done semi manually. Presumably someone skilled at
> coccinelle could do a better job, but I just used sed in a heavy-
> handed manner and then reviewed/fixed the results, undoing anything my
> script got wrong. My terrible/ugly script was:
>
> var=can_match
> caps="${var^^}"
> for f in $(git grep -l "[>\.]${var}[^1-9_a-zA-Z\[]"); do
>   echo $f
>   sed -i~ -e "s/\([a-zA-Z_0-9\.>()-][a-zA-Z_0-9\.>()-]*\)->${var} = true/set_bit(DEV_FLAG_${caps}, \&\\1->flags)/" "$f"
>   sed -i~ -e "s/\([a-zA-Z_0-9\.>()-][a-zA-Z_0-9\.>()-]*\)\.${var} = true/dev_set_${caps}(\&\\1)/" "$f"
>   sed -i~ -e "s/\([a-zA-Z_0-9\.>()-][a-zA-Z_0-9\.>()-]*\)->${var} = false/clear_bit(DEV_FLAG_${caps}, \&\\1->flags)/" "$f"
>   sed -i~ -e "s/\([a-zA-Z_0-9\.>()-][a-zA-Z_0-9\.>()-]*\)\.${var} = false/dev_clear_${caps}(\&\\1)/" "$f"
>   sed -i~ -e "s/\([a-zA-Z_0-9\.>()-][a-zA-Z_0-9\.>()-]*\)->${var} = \([^;]*\)/assign_bit(DEV_FLAG_${caps}, \&\\1->flags, \\2)/" "$f"
>   sed -i~ -e "s/\([a-zA-Z_0-9\.>()-][a-zA-Z_0-9\.>()-]*\)\.${var} = \([^;]*\)/dev_assign_${caps}(\&\\1, \\2)/" "$f"
>   sed -i~ -e "s/\([a-zA-Z_0-9\.>()-][a-zA-Z_0-9\.>()-]*\)->${var}\([^1-9_a-zA-Z\[]\)/test_bit(DEV_FLAG_${caps}, \&\\1->flags)\\2/" "$f"
>   sed -i~ -e "s/\([a-zA-Z_0-9\.>()-][a-zA-Z_0-9\.>()-]*\)\.${var}\([^1-9_a-zA-Z\[]\)/dev_${caps}(\&\\1)\\2/" "$f"
> done
>
> From v3 to v4, I transitioned to accessor functions with another ugly
> sed script. I had git format the old patches, then transformed them
> with:
>
> for f in *.patch; do
>   echo $f
>   sed -i~ -e "s/test_and_set_bit(DEV_FLAG_\([^,]*\), \&\(.*\)->flags)/dev_test_and_set_\\L\\1(\\2)/" "$f"
>   sed -i~ -e "s/test_and_set_bit(DEV_FLAG_\([^,]*\), \(.*\)\.flags)/dev_test_and_set_\\L\\1(\\2)/" "$f"
>   sed -i~ -e "s/test_bit(DEV_FLAG_\([^,]*\), \&\(.*\)->flags)/dev_\\L\\1(\\2)/" "$f"
>   sed -i~ -e "s/test_bit(DEV_FLAG_\([^,]*\), \(.*\)\.flags)/dev_\\L\\1(\\2)/" "$f"
>   sed -i~ -e "s/set_bit(DEV_FLAG_\([^,]*\), \&\(.*\)->flags)/dev_set_\\L\\1(\\2)/" "$f"
>   sed -i~ -e "s/set_bit(DEV_FLAG_\([^,]*\), \(.*\)\.flags)/dev_set_\\L\\1(\\2)/" "$f"
>   sed -i~ -e "s/clear_bit(DEV_FLAG_\([^,]*\), \&\(.*\)->flags)/dev_clear_\\L\\1(\\2)/" "$f"
>   sed -i~ -e "s/clear_bit(DEV_FLAG_\([^,]*\), \(.*\)\.flags)/dev_clear_\\L\\1(\\2)/" "$f"
>   sed -i~ -e "s/assign_bit(DEV_FLAG_\([^,]*\), \&\(.*\)->flags, \(.*\))/dev_assign_\\L\\1(\\2, \\3)/" "$f"
>   sed -i~ -e "s/assign_bit(DEV_FLAG_\([^,]*\), \(.*\)\.flags, \(.*\))/dev_assign_\\L\\1(\\2, \\3)/" "$f"
> done
>
> ...and then did a few manual touchups for spacing.
>
> I only marked the first patch as a "Fix" since it is the only one
> fixing observed problems. Other patches could be considered fixes too
> if folks want.
>
> I tested the first patch in the series backported to kernel 6.6 on the
> Pixel phone that was experiencing the race. I added extra printouts to
> make sure that the problem was hitting / addressed. The rest of the
> patches are tested with allmodconfig with arm32, arm64, ppc, and
> x86. I boot tested on an arm64 Chromebook running mainline.
The dma-mapping related bits are probably not race prone, but if you plan
to refactor that part I won't object.

Acked-by: Marek Szyprowski


> Changes in v5:
> - ready_to_prove => ready_to_probe typo
> - device_lock() while calling dev_set_ready_to_probe()
> - Add comment before "can_match = true" from Danilo.
> - undef __create_dev_flag_accessors
>
> Changes in v4:
> - Use accessor functions for flags
>
> Changes in v3:
> - Use a new "flags" bitfield
> - Add missing \n in probe error message
>
> Changes in v2:
> - Instead of adjusting the ordering, use "ready_to_probe" flag
>
> Douglas Anderson (9):
>   driver core: Don't let a device probe until it's ready
>   driver core: Replace dev->can_match with dev_can_match()
>   driver core: Replace dev->dma_iommu with dev_dma_iommu()
>   driver core: Replace dev->dma_skip_sync with dev_dma_skip_sync()
>   driver core: Replace dev->dma_ops_bypass with dev_dma_ops_bypass()
>   driver core: Replace dev->state_synced with dev_state_synced()
>   driver core: Replace dev->dma_coherent with dev_dma_coherent()
>   driver core: Replace dev->of_node_reused with dev_of_node_reused()
>   driver core: Replace dev->offline + ->offline_disabled with accessors
>
>  arch/arc/mm/dma.c                             |   4 +-
>  arch/arm/mach-highbank/highbank.c             |   2 +-
>  arch/arm/mach-mvebu/coherency.c               |   2 +-
>  arch/arm/mm/dma-mapping-nommu.c               |   4 +-
>  arch/arm/mm/dma-mapping.c                     |  28 ++--
>  arch/arm64/kernel/cpufeature.c                |   2 +-
>  arch/arm64/mm/dma-mapping.c                   |   2 +-
>  arch/mips/mm/dma-noncoherent.c                |   2 +-
>  arch/powerpc/kernel/dma-iommu.c               |   8 +-
>  .../platforms/pseries/hotplug-memory.c        |   4 +-
>  arch/riscv/mm/dma-noncoherent.c               |   2 +-
>  drivers/acpi/scan.c                           |   2 +-
>  drivers/base/core.c                           |  55 +++++---
>  drivers/base/cpu.c                            |   4 +-
>  drivers/base/dd.c                             |  36 ++++--
>  drivers/base/memory.c                         |   2 +-
>  drivers/base/pinctrl.c                        |   2 +-
>  drivers/base/platform.c                       |   2 +-
>  drivers/dma/ti/k3-udma-glue.c                 |   6 +-
>  drivers/dma/ti/k3-udma.c                      |   6 +-
>  drivers/iommu/dma-iommu.c                     |   9 +-
>  drivers/iommu/iommu.c                         |   5 +-
>  drivers/net/pcs/pcs-xpcs-plat.c               |   2 +-
>  drivers/of/device.c                           |   6 +-
>  drivers/pci/of.c                              |   2 +-
>  drivers/pci/pwrctrl/core.c                    |   2 +-
>  drivers/regulator/bq257xx-regulator.c         |   2 +-
>  drivers/regulator/rk808-regulator.c           |   2 +-
>  drivers/tty/serial/serial_base_bus.c          |   2 +-
>  drivers/usb/gadget/udc/aspeed-vhub/dev.c      |   2 +-
>  include/linux/device.h                        | 122 ++++++++++++------
>  include/linux/dma-map-ops.h                   |   6 +-
>  include/linux/dma-mapping.h                   |   2 +-
>  include/linux/iommu-dma.h                     |   3 +-
>  kernel/cpu.c                                  |   4 +-
>  kernel/dma/mapping.c                          |  12 +-
>  mm/hmm.c                                      |   2 +-
>  37 files changed, 218 insertions(+), 142 deletions(-)
>
Best regards

-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland