* [PATCH v4 0/9] driver core: Fix some race conditions
@ 2026-04-04 0:04 Douglas Anderson
2026-04-04 0:05 ` [PATCH v4 8/9] driver core: Replace dev->of_node_reused with dev_of_node_reused() Douglas Anderson
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: Douglas Anderson @ 2026-04-04 0:04 UTC (permalink / raw)
To: Greg Kroah-Hartman, Rafael J . Wysocki, Danilo Krummrich,
Alan Stern
Cc: Saravana Kannan, Christoph Hellwig, Eric Dumazet, Johan Hovold,
Leon Romanovsky, Alexander Lobakin, Alexey Kardashevskiy,
Robin Murphy, Douglas Anderson, Andrew Morton, Frank.Li,
Jason Gunthorpe, alex, alexander.stein, andre.przywara, andrew,
andrew, andriy.shevchenko, aou, ardb, bhelgaas, brgl, broonie,
catalin.marinas, chleroy, davem, david, devicetree, dmaengine,
driver-core, gbatra, gregory.clement, hkallweit1, iommu,
jirislaby, joel, joro, kees, kevin.brodsky, kuba, lenb, lgirdwood,
linux-acpi, linux-arm-kernel, linux-aspeed, linux-cxl,
linux-kernel, linux-mips, linux-mm, linux-pci, linux-riscv,
linux-serial, linux-snps-arc, linux-usb, linux, linuxppc-dev,
m.szyprowski, maddy, mani, maz, miko.lenczewski, mpe, netdev,
npiggin, osalvador, oupton, pabeni, palmer, peter.ujfalusi,
peterz, pjw, robh, sebastian.hesselbarth, tglx, tsbogend, vgupta,
vkoul, will, willy, yangyicong, yeoreum.yun
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.
NOTE: one potentially "controversial" choice I made in some patches
was to always reserve a flag ID even if a flag is only used under
certain CONFIG_ settings. This is a change from how things were
before. Keeping the numbering consistent and allowing easy
compile-testing of both CONFIG settings seemed worth it, especially
since it won't take up any extra space until we've added a lot more
flags.
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.
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 | 53 +++++---
drivers/base/cpu.c | 4 +-
drivers/base/dd.c | 28 ++--
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 | 120 ++++++++++++------
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, 206 insertions(+), 142 deletions(-)
--
2.53.0.1213.gd9a14994de-goog
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH v4 8/9] driver core: Replace dev->of_node_reused with dev_of_node_reused()
2026-04-04 0:04 [PATCH v4 0/9] driver core: Fix some race conditions Douglas Anderson
@ 2026-04-04 0:05 ` Douglas Anderson
2026-04-04 17:11 ` [PATCH v4 0/9] driver core: Fix some race conditions Rafael J. Wysocki
2026-04-05 5:27 ` Greg Kroah-Hartman
2 siblings, 0 replies; 6+ messages in thread
From: Douglas Anderson @ 2026-04-04 0:05 UTC (permalink / raw)
To: Greg Kroah-Hartman, Rafael J . Wysocki, Danilo Krummrich,
Alan Stern
Cc: Saravana Kannan, Christoph Hellwig, Eric Dumazet, Johan Hovold,
Leon Romanovsky, Alexander Lobakin, Alexey Kardashevskiy,
Robin Murphy, Douglas Anderson, Mark Brown, alexander.stein,
andrew, andrew, andriy.shevchenko, bhelgaas, brgl, davem,
devicetree, driver-core, hkallweit1, jirislaby, joel, kees, kuba,
lgirdwood, linux-arm-kernel, linux-aspeed, linux-kernel,
linux-pci, linux-serial, linux-usb, linux, mani, netdev, pabeni,
robh
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>
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).
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 531f02a5469a..f12f3b53b4d0 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -5281,7 +5281,7 @@ 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 fca986cef2ed..8132aab17e04 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);
/**
* struct device_link - Device link representation.
--
2.53.0.1213.gd9a14994de-goog
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH v4 0/9] driver core: Fix some race conditions
2026-04-04 0:04 [PATCH v4 0/9] driver core: Fix some race conditions Douglas Anderson
2026-04-04 0:05 ` [PATCH v4 8/9] driver core: Replace dev->of_node_reused with dev_of_node_reused() Douglas Anderson
@ 2026-04-04 17:11 ` Rafael J. Wysocki
2026-04-05 5:27 ` Greg Kroah-Hartman
2 siblings, 0 replies; 6+ messages in thread
From: Rafael J. Wysocki @ 2026-04-04 17:11 UTC (permalink / raw)
To: Douglas Anderson
Cc: Greg Kroah-Hartman, Rafael J . Wysocki, Danilo Krummrich,
Alan Stern, Saravana Kannan, Christoph Hellwig, Eric Dumazet,
Johan Hovold, Leon Romanovsky, Alexander Lobakin,
Alexey Kardashevskiy, Robin Murphy, Andrew Morton, Frank.Li,
Jason Gunthorpe, alex, alexander.stein, andre.przywara, andrew,
andrew, andriy.shevchenko, aou, ardb, bhelgaas, brgl, broonie,
catalin.marinas, chleroy, davem, david, devicetree, dmaengine,
driver-core, gbatra, gregory.clement, hkallweit1, iommu,
jirislaby, joel, joro, kees, kevin.brodsky, kuba, lenb, lgirdwood,
linux-acpi, linux-arm-kernel, linux-aspeed, linux-cxl,
linux-kernel, linux-mips, linux-mm, linux-pci, linux-riscv,
linux-serial, linux-snps-arc, linux-usb, linux, linuxppc-dev,
m.szyprowski, maddy, mani, maz, miko.lenczewski, mpe, netdev,
npiggin, osalvador, oupton, pabeni, palmer, peter.ujfalusi,
peterz, pjw, robh, sebastian.hesselbarth, tglx, tsbogend, vgupta,
vkoul, will, willy, yangyicong, yeoreum.yun
On Sat, Apr 4, 2026 at 2:07 AM Douglas Anderson <dianders@chromium.org> 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.
>
> NOTE: one potentially "controversial" choice I made in some patches
> was to always reserve a flag ID even if a flag is only used under
> certain CONFIG_ settings. This is a change from how things were
> before. Keeping the numbering consistent and allowing easy
> compile-testing of both CONFIG settings seemed worth it, especially
> since it won't take up any extra space until we've added a lot more
> flags.
>
> 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.
>
> 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 | 53 +++++---
> drivers/base/cpu.c | 4 +-
> drivers/base/dd.c | 28 ++--
> 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 | 120 ++++++++++++------
> 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, 206 insertions(+), 142 deletions(-)
>
> --
For the whole set
Reviewed-by: Rafael J. Wysocki (Intel) <rafael@kernel.org>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v4 0/9] driver core: Fix some race conditions
2026-04-04 0:04 [PATCH v4 0/9] driver core: Fix some race conditions Douglas Anderson
2026-04-04 0:05 ` [PATCH v4 8/9] driver core: Replace dev->of_node_reused with dev_of_node_reused() Douglas Anderson
2026-04-04 17:11 ` [PATCH v4 0/9] driver core: Fix some race conditions Rafael J. Wysocki
@ 2026-04-05 5:27 ` Greg Kroah-Hartman
2026-04-05 12:02 ` Danilo Krummrich
2026-04-05 22:43 ` Doug Anderson
2 siblings, 2 replies; 6+ messages in thread
From: Greg Kroah-Hartman @ 2026-04-05 5:27 UTC (permalink / raw)
To: Douglas Anderson
Cc: Rafael J . Wysocki, Danilo Krummrich, Alan Stern, Saravana Kannan,
Christoph Hellwig, Eric Dumazet, Johan Hovold, Leon Romanovsky,
Alexander Lobakin, Alexey Kardashevskiy, Robin Murphy,
Andrew Morton, Frank.Li, Jason Gunthorpe, alex, alexander.stein,
andre.przywara, andrew, andrew, andriy.shevchenko, aou, ardb,
bhelgaas, brgl, broonie, catalin.marinas, chleroy, davem, david,
devicetree, dmaengine, driver-core, gbatra, gregory.clement,
hkallweit1, iommu, jirislaby, joel, joro, kees, kevin.brodsky,
kuba, lenb, lgirdwood, linux-acpi, linux-arm-kernel, linux-aspeed,
linux-cxl, linux-kernel, linux-mips, linux-mm, linux-pci,
linux-riscv, linux-serial, linux-snps-arc, linux-usb, linux,
linuxppc-dev, m.szyprowski, maddy, mani, maz, miko.lenczewski,
mpe, netdev, npiggin, osalvador, oupton, pabeni, palmer,
peter.ujfalusi, peterz, pjw, robh, sebastian.hesselbarth, tglx,
tsbogend, vgupta, vkoul, will, willy, yangyicong, yeoreum.yun
On Fri, Apr 03, 2026 at 05:04:54PM -0700, Douglas Anderson wrote:
> NOTE: one potentially "controversial" choice I made in some patches
> was to always reserve a flag ID even if a flag is only used under
> certain CONFIG_ settings. This is a change from how things were
> before. Keeping the numbering consistent and allowing easy
> compile-testing of both CONFIG settings seemed worth it, especially
> since it won't take up any extra space until we've added a lot more
> flags.
Nah, this is fine, I don't see any problems with this as the original
code kind of was doing the same thing with the "hole" in the structure
if those options were not enabled.
> 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.
I'm guessing your tests passed? :)
Anyway, this looks great, unless there are any objections, other than
the "needs to be undefined", which a follow-on patch can handle, I'll
queue them up next week for 7.1-rc1.
thanks,
greg k-h
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v4 0/9] driver core: Fix some race conditions
2026-04-05 5:27 ` Greg Kroah-Hartman
@ 2026-04-05 12:02 ` Danilo Krummrich
2026-04-05 22:43 ` Doug Anderson
1 sibling, 0 replies; 6+ messages in thread
From: Danilo Krummrich @ 2026-04-05 12:02 UTC (permalink / raw)
To: Greg Kroah-Hartman
Cc: Douglas Anderson, Rafael J . Wysocki, Alan Stern, Saravana Kannan,
Christoph Hellwig, Eric Dumazet, Johan Hovold, Leon Romanovsky,
Alexander Lobakin, Alexey Kardashevskiy, Robin Murphy,
Andrew Morton, Frank.Li, Jason Gunthorpe, alex, alexander.stein,
andre.przywara, andrew, andrew, andriy.shevchenko, aou, ardb,
bhelgaas, brgl, broonie, catalin.marinas, chleroy, davem, david,
devicetree, dmaengine, driver-core, gbatra, gregory.clement,
hkallweit1, iommu, jirislaby, joel, joro, kees, kevin.brodsky,
kuba, lenb, lgirdwood, linux-acpi, linux-arm-kernel, linux-aspeed,
linux-cxl, linux-kernel, linux-mips, linux-mm, linux-pci,
linux-riscv, linux-serial, linux-snps-arc, linux-usb, linux,
linuxppc-dev, m.szyprowski, maddy, mani, maz, miko.lenczewski,
mpe, netdev, npiggin, osalvador, oupton, pabeni, palmer,
peter.ujfalusi, peterz, pjw, robh, sebastian.hesselbarth, tglx,
tsbogend, vgupta, vkoul, will, willy, yangyicong, yeoreum.yun
On Sun Apr 5, 2026 at 7:27 AM CEST, Greg Kroah-Hartman wrote:
> Anyway, this looks great, unless there are any objections, other than
> the "needs to be undefined", which a follow-on patch can handle, I'll
> queue them up next week for 7.1-rc1.
Sounds good, for the series:
Reviewed-by: Danilo Krummrich <dakr@kernel.org>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v4 0/9] driver core: Fix some race conditions
2026-04-05 5:27 ` Greg Kroah-Hartman
2026-04-05 12:02 ` Danilo Krummrich
@ 2026-04-05 22:43 ` Doug Anderson
1 sibling, 0 replies; 6+ messages in thread
From: Doug Anderson @ 2026-04-05 22:43 UTC (permalink / raw)
To: Greg Kroah-Hartman
Cc: Rafael J . Wysocki, Danilo Krummrich, Alan Stern, Saravana Kannan,
Christoph Hellwig, Eric Dumazet, Johan Hovold, Leon Romanovsky,
Alexander Lobakin, Alexey Kardashevskiy, Robin Murphy,
Andrew Morton, Frank.Li, Jason Gunthorpe, alex, alexander.stein,
andre.przywara, andrew, andrew, andriy.shevchenko, aou, ardb,
bhelgaas, brgl, broonie, catalin.marinas, chleroy, davem, david,
devicetree, dmaengine, driver-core, gbatra, gregory.clement,
hkallweit1, iommu, jirislaby, joel, joro, kees, kevin.brodsky,
kuba, lenb, lgirdwood, linux-acpi, linux-arm-kernel, linux-aspeed,
linux-cxl, linux-kernel, linux-mips, linux-mm, linux-pci,
linux-riscv, linux-serial, linux-snps-arc, linux-usb, linux,
linuxppc-dev, m.szyprowski, maddy, mani, maz, miko.lenczewski,
mpe, netdev, npiggin, osalvador, oupton, pabeni, palmer,
peter.ujfalusi, peterz, pjw, robh, sebastian.hesselbarth, tglx,
tsbogend, vgupta, vkoul, will, willy, yangyicong, yeoreum.yun
Hi,
On Sat, Apr 4, 2026 at 10:28 PM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Fri, Apr 03, 2026 at 05:04:54PM -0700, Douglas Anderson wrote:
> > NOTE: one potentially "controversial" choice I made in some patches
> > was to always reserve a flag ID even if a flag is only used under
> > certain CONFIG_ settings. This is a change from how things were
> > before. Keeping the numbering consistent and allowing easy
> > compile-testing of both CONFIG settings seemed worth it, especially
> > since it won't take up any extra space until we've added a lot more
> > flags.
>
> Nah, this is fine, I don't see any problems with this as the original
> code kind of was doing the same thing with the "hole" in the structure
> if those options were not enabled.
>
> > 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.
>
> I'm guessing your tests passed? :)
Yup, all the tests that I've run have passed. I also threw in an
"allnoconfig" compile test just for good measure.
> Anyway, this looks great, unless there are any objections, other than
> the "needs to be undefined", which a follow-on patch can handle, I'll
> queue them up next week for 7.1-rc1.
Thanks. As per the other thread, I'm happy if you or Danilo want to
apply it, and I'm happy if you want to make minor fixups when
applying.
When I see the patches applied, I'll send a followup patch to address
the "needs to be undefined" comment, unless Danilo makes that change
himself when applying.
-Doug
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2026-04-05 22:50 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
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2026-04-04 0:04 [PATCH v4 0/9] driver core: Fix some race conditions Douglas Anderson
2026-04-04 0:05 ` [PATCH v4 8/9] driver core: Replace dev->of_node_reused with dev_of_node_reused() Douglas Anderson
2026-04-04 17:11 ` [PATCH v4 0/9] driver core: Fix some race conditions Rafael J. Wysocki
2026-04-05 5:27 ` Greg Kroah-Hartman
2026-04-05 12:02 ` Danilo Krummrich
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