linux-stable.git/drivers/base/core.c, branch v6.12.89 Linux kernel stable tree device property: Make modifications of fwnode "flags" thread safe 2026-05-07T04:09:26+00:00 Douglas Anderson dianders@chromium.org 2026-03-17T16:01:20+00:00 e42527bf30589c14e8b53dff2ae27adb0b0aa8bb commit f72e77c33e4b5657af35125e75bab249256030f3 upstream. 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit f72e77c33e4b5657af35125e75bab249256030f3 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
driver core: Don't let a device probe until it's ready 2026-05-07T04:09:24+00:00 Douglas Anderson dianders@chromium.org 2026-04-06T23:22:54+00:00 88e338bd9b6ef9df1282e406dae21c69405ded71 commit a2225b6e834a838ae3c93709760edc0a169eb2f2 upstream. The moment we link a "struct device" into the list of devices for the bus, it's possible probe can happen. This is because another thread can load the driver at any time and that can cause the device to probe. This has been seen in practice with a stack crawl that looks like this [1]: really_probe() __driver_probe_device() driver_probe_device() __driver_attach() bus_for_each_dev() driver_attach() bus_add_driver() driver_register() __platform_driver_register() init_module() [some module] do_one_initcall() do_init_module() load_module() __arm64_sys_finit_module() invoke_syscall() As a result of the above, it was seen that device_links_driver_bound() could be called for the device before "dev->fwnode->dev" was assigned. This prevented __fw_devlink_pickup_dangling_consumers() from being called which meant that other devices waiting on our driver's sub-nodes were stuck deferring forever. It's believed that this problem is showing up suddenly for two reasons: 1. Android has recently (last ~1 year) implemented an optimization to the order it loads modules [2]. When devices opt-in to this faster loading, modules are loaded one-after-the-other very quickly. This is unlike how other distributions do it. The reproduction of this problem has only been seen on devices that opt-in to Android's "parallel module loading". 2. Android devices typically opt-in to fw_devlink, and the most noticeable issue is the NULL "dev->fwnode->dev" in device_links_driver_bound(). fw_devlink is somewhat new code and also not in use by all Linux devices. Even though the specific symptom where "dev->fwnode->dev" wasn't assigned could be fixed by moving that assignment higher in device_add(), other parts of device_add() (like the call to device_pm_add()) are also important to run before probe. Only moving the "dev->fwnode->dev" assignment would likely fix the current symptoms but lead to difficult-to-debug problems in the future. Fix the problem by preventing probe until device_add() has run far enough that the device is ready to probe. If somehow we end up trying to probe before we're allowed, __driver_probe_device() will return -EPROBE_DEFER which will make certain the device is noticed. In the race condition that was seen with Android's faster module loading, we will temporarily add the device to the deferred list and then take it off immediately when device_add() probes the device. Instead of adding another flag to the bitfields already in "struct device", instead add a new "flags" field and use that. This allows us to freely change the bit from different thread without worrying about corrupting nearby bits (and means threads changing other bit won't corrupt us). [1] Captured on a machine running a downstream 6.6 kernel [2] https://cs.android.com/android/platform/superproject/main/+/main:system/core/libmodprobe/libmodprobe.cpp?q=LoadModulesParallel Cc: stable@vger.kernel.org Fixes: 2023c610dc54 ("Driver core: add new device to bus's list before probing") Reviewed-by: Alan Stern <stern@rowland.harvard.edu> Reviewed-by: Rafael J. Wysocki (Intel) <rafael@kernel.org> Reviewed-by: Danilo Krummrich <dakr@kernel.org> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Acked-by: Marek Szyprowski <m.szyprowski@samsung.com> Signed-off-by: Douglas Anderson <dianders@chromium.org> Link: https://patch.msgid.link/20260406162231.v5.1.Id750b0fbcc94f23ed04b7aecabcead688d0d8c17@changeid Signed-off-by: Danilo Krummrich <dakr@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit a2225b6e834a838ae3c93709760edc0a169eb2f2 upstream.

The moment we link a "struct device" into the list of devices for the
bus, it's possible probe can happen. This is because another thread
can load the driver at any time and that can cause the device to
probe. This has been seen in practice with a stack crawl that looks
like this [1]:

  really_probe()
  __driver_probe_device()
  driver_probe_device()
  __driver_attach()
  bus_for_each_dev()
  driver_attach()
  bus_add_driver()
  driver_register()
  __platform_driver_register()
  init_module() [some module]
  do_one_initcall()
  do_init_module()
  load_module()
  __arm64_sys_finit_module()
  invoke_syscall()

As a result of the above, it was seen that device_links_driver_bound()
could be called for the device before "dev->fwnode->dev" was
assigned. This prevented __fw_devlink_pickup_dangling_consumers() from
being called which meant that other devices waiting on our driver's
sub-nodes were stuck deferring forever.

It's believed that this problem is showing up suddenly for two
reasons:
1. Android has recently (last ~1 year) implemented an optimization to
   the order it loads modules [2]. When devices opt-in to this faster
   loading, modules are loaded one-after-the-other very quickly. This
   is unlike how other distributions do it. The reproduction of this
   problem has only been seen on devices that opt-in to Android's
   "parallel module loading".
2. Android devices typically opt-in to fw_devlink, and the most
   noticeable issue is the NULL "dev->fwnode->dev" in
   device_links_driver_bound(). fw_devlink is somewhat new code and
   also not in use by all Linux devices.

Even though the specific symptom where "dev->fwnode->dev" wasn't
assigned could be fixed by moving that assignment higher in
device_add(), other parts of device_add() (like the call to
device_pm_add()) are also important to run before probe. Only moving
the "dev->fwnode->dev" assignment would likely fix the current
symptoms but lead to difficult-to-debug problems in the future.

Fix the problem by preventing probe until device_add() has run far
enough that the device is ready to probe. If somehow we end up trying
to probe before we're allowed, __driver_probe_device() will return
-EPROBE_DEFER which will make certain the device is noticed.

In the race condition that was seen with Android's faster module
loading, we will temporarily add the device to the deferred list and
then take it off immediately when device_add() probes the device.

Instead of adding another flag to the bitfields already in "struct
device", instead add a new "flags" field and use that. This allows us
to freely change the bit from different thread without worrying about
corrupting nearby bits (and means threads changing other bit won't
corrupt us).

[1] Captured on a machine running a downstream 6.6 kernel
[2] https://cs.android.com/android/platform/superproject/main/+/main:system/core/libmodprobe/libmodprobe.cpp?q=LoadModulesParallel

Cc: stable@vger.kernel.org
Fixes: 2023c610dc54 ("Driver core: add new device to bus's list before probing")
Reviewed-by: Alan Stern <stern@rowland.harvard.edu>
Reviewed-by: Rafael J. Wysocki (Intel) <rafael@kernel.org>
Reviewed-by: Danilo Krummrich <dakr@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://patch.msgid.link/20260406162231.v5.1.Id750b0fbcc94f23ed04b7aecabcead688d0d8c17@changeid
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
driver core: generalize driver_override in struct device 2026-04-02T11:09:25+00:00 Danilo Krummrich dakr@kernel.org 2026-03-03T11:53:18+00:00 78aba57ca3de5ecebe2c45bd82eb14d2d41b297b [ Upstream commit cb3d1049f4ea77d5ad93f17d8ac1f2ed4da70501 ] Currently, there are 12 busses (including platform and PCI) that duplicate the driver_override logic for their individual devices. All of them seem to be prone to the bug described in [1]. While this could be solved for every bus individually using a separate lock, solving this in the driver-core generically results in less (and cleaner) changes overall. Thus, move driver_override to struct device, provide corresponding accessors for busses and handle locking with a separate lock internally. In particular, add device_set_driver_override(), device_has_driver_override(), device_match_driver_override() and generalize the sysfs store() and show() callbacks via a driver_override feature flag in struct bus_type. Until all busses have migrated, keep driver_set_override() in place. Note that we can't use the device lock for the reasons described in [2]. Link: https://bugzilla.kernel.org/show_bug.cgi?id=220789 [1] Link: https://lore.kernel.org/driver-core/DGRGTIRHA62X.3RY09D9SOK77P@kernel.org/ [2] Tested-by: Gui-Dong Han <hanguidong02@gmail.com> Co-developed-by: Gui-Dong Han <hanguidong02@gmail.com> Signed-off-by: Gui-Dong Han <hanguidong02@gmail.com> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Link: https://patch.msgid.link/20260303115720.48783-2-dakr@kernel.org [ Use dev->bus instead of sp->bus for consistency; fix commit message to refer to the struct bus_type's driver_override feature flag. - Danilo ] Signed-off-by: Danilo Krummrich <dakr@kernel.org> Stable-dep-of: 2b38efc05bf7 ("driver core: platform: use generic driver_override infrastructure") Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit cb3d1049f4ea77d5ad93f17d8ac1f2ed4da70501 ]

Currently, there are 12 busses (including platform and PCI) that
duplicate the driver_override logic for their individual devices.

All of them seem to be prone to the bug described in [1].

While this could be solved for every bus individually using a separate
lock, solving this in the driver-core generically results in less (and
cleaner) changes overall.

Thus, move driver_override to struct device, provide corresponding
accessors for busses and handle locking with a separate lock internally.

In particular, add device_set_driver_override(),
device_has_driver_override(), device_match_driver_override() and
generalize the sysfs store() and show() callbacks via a driver_override
feature flag in struct bus_type.

Until all busses have migrated, keep driver_set_override() in place.

Note that we can't use the device lock for the reasons described in [2].

Link: https://bugzilla.kernel.org/show_bug.cgi?id=220789 [1]
Link: https://lore.kernel.org/driver-core/DGRGTIRHA62X.3RY09D9SOK77P@kernel.org/ [2]
Tested-by: Gui-Dong Han <hanguidong02@gmail.com>
Co-developed-by: Gui-Dong Han <hanguidong02@gmail.com>
Signed-off-by: Gui-Dong Han <hanguidong02@gmail.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://patch.msgid.link/20260303115720.48783-2-dakr@kernel.org
[ Use dev->bus instead of sp->bus for consistency; fix commit message to
  refer to the struct bus_type's driver_override feature flag. - Danilo ]
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
Stable-dep-of: 2b38efc05bf7 ("driver core: platform: use generic driver_override infrastructure")
Signed-off-by: Sasha Levin <sashal@kernel.org>
driver core: fix potential NULL pointer dereference in dev_uevent() 2025-05-02T05:59:29+00:00 Dmitry Torokhov dmitry.torokhov@gmail.com 2025-03-11T05:24:16+00:00 2b344e779d9afd0fcb5ee4000e4d0fc7d8d867eb commit 18daa52418e7e4629ed1703b64777294209d2622 upstream. If userspace reads "uevent" device attribute at the same time as another threads unbinds the device from its driver, change to dev->driver from a valid pointer to NULL may result in crash. Fix this by using READ_ONCE() when fetching the pointer, and take bus' drivers klist lock to make sure driver instance will not disappear while we access it. Use WRITE_ONCE() when setting the driver pointer to ensure there is no tearing. Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Link: https://lore.kernel.org/r/20250311052417.1846985-3-dmitry.torokhov@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 18daa52418e7e4629ed1703b64777294209d2622 upstream.

If userspace reads "uevent" device attribute at the same time as another
threads unbinds the device from its driver, change to dev->driver from a
valid pointer to NULL may result in crash. Fix this by using READ_ONCE()
when fetching the pointer, and take bus' drivers klist lock to make sure
driver instance will not disappear while we access it.

Use WRITE_ONCE() when setting the driver pointer to ensure there is no
tearing.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Link: https://lore.kernel.org/r/20250311052417.1846985-3-dmitry.torokhov@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
driver core: introduce device_set_driver() helper 2025-05-02T05:59:28+00:00 Dmitry Torokhov dmitry.torokhov@gmail.com 2025-03-11T05:24:15+00:00 4f43c1bf2b1aa10d5b6926ca4eb859eed4689f5e commit 04d3e5461c1f5cf8eec964ab64948ebed826e95e upstream. In preparation to closing a race when reading driver pointer in dev_uevent() code, instead of setting device->driver pointer directly introduce device_set_driver() helper. Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Link: https://lore.kernel.org/r/20250311052417.1846985-2-dmitry.torokhov@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 04d3e5461c1f5cf8eec964ab64948ebed826e95e upstream.

In preparation to closing a race when reading driver pointer in
dev_uevent() code, instead of setting device->driver pointer directly
introduce device_set_driver() helper.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Link: https://lore.kernel.org/r/20250311052417.1846985-2-dmitry.torokhov@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Revert "drivers: core: synchronize really_probe() and dev_uevent()" 2025-05-02T05:59:28+00:00 Dmitry Torokhov dmitry.torokhov@gmail.com 2025-03-11T05:24:14+00:00 bfc66c4c28041ffb199fbbdbeedf336a4ef25356 commit dc1771f718548f7d4b93991b174c6e7b5e1ba410 upstream. This reverts commit c0a40097f0bc81deafc15f9195d1fb54595cd6d0. Probing a device can take arbitrary long time. In the field we observed that, for example, probing a bad micro-SD cards in an external USB card reader (or maybe cards were good but cables were flaky) sometimes takes longer than 2 minutes due to multiple retries at various levels of the stack. We can not block uevent_show() method for that long because udev is reading that attribute very often and that blocks udev and interferes with booting of the system. The change that introduced locking was concerned with dev_uevent() racing with unbinding the driver. However we can handle it without locking (which will be done in subsequent patch). There was also claim that synchronization with probe() is needed to properly load USB drivers, however this is a red herring: the change adding the lock was introduced in May of last year and USB loading and probing worked properly for many years before that. Revert the harmful locking. Cc: stable@vger.kernel.org Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Link: https://lore.kernel.org/r/20250311052417.1846985-1-dmitry.torokhov@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit dc1771f718548f7d4b93991b174c6e7b5e1ba410 upstream.

This reverts commit c0a40097f0bc81deafc15f9195d1fb54595cd6d0.

Probing a device can take arbitrary long time. In the field we observed
that, for example, probing a bad micro-SD cards in an external USB card
reader (or maybe cards were good but cables were flaky) sometimes takes
longer than 2 minutes due to multiple retries at various levels of the
stack. We can not block uevent_show() method for that long because udev
is reading that attribute very often and that blocks udev and interferes
with booting of the system.

The change that introduced locking was concerned with dev_uevent()
racing with unbinding the driver. However we can handle it without
locking (which will be done in subsequent patch).

There was also claim that synchronization with probe() is needed to
properly load USB drivers, however this is a red herring: the change
adding the lock was introduced in May of last year and USB loading and
probing worked properly for many years before that.

Revert the harmful locking.

Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Link: https://lore.kernel.org/r/20250311052417.1846985-1-dmitry.torokhov@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers: core: fix device leak in __fw_devlink_relax_cycles() 2025-03-13T12:02:16+00:00 Luca Ceresoli luca.ceresoli@bootlin.com 2025-02-13T14:05:13+00:00 b50e18791f4098da4d0303ae6914078e8a8dce8a commit 78eb41f518f414378643ab022241df2a9dcd008b upstream. Commit bac3b10b78e5 ("driver core: fw_devlink: Stop trying to optimize cycle detection logic") introduced a new struct device *con_dev and a get_dev_from_fwnode() call to get it, but without adding a corresponding put_device(). Closes: https://lore.kernel.org/all/20241204124826.2e055091@booty/ Fixes: bac3b10b78e5 ("driver core: fw_devlink: Stop trying to optimize cycle detection logic") Cc: stable@vger.kernel.org Reviewed-by: Saravana Kannan <saravanak@google.com> Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com> Link: https://lore.kernel.org/r/20250213-fix__fw_devlink_relax_cycles_missing_device_put-v2-1-8cd3b03e6a3f@bootlin.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 78eb41f518f414378643ab022241df2a9dcd008b upstream.

Commit bac3b10b78e5 ("driver core: fw_devlink: Stop trying to optimize
cycle detection logic") introduced a new struct device *con_dev and a
get_dev_from_fwnode() call to get it, but without adding a corresponding
put_device().

Closes: https://lore.kernel.org/all/20241204124826.2e055091@booty/
Fixes: bac3b10b78e5 ("driver core: fw_devlink: Stop trying to optimize cycle detection logic")
Cc: stable@vger.kernel.org
Reviewed-by: Saravana Kannan <saravanak@google.com>
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Link: https://lore.kernel.org/r/20250213-fix__fw_devlink_relax_cycles_missing_device_put-v2-1-8cd3b03e6a3f@bootlin.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
driver core: fw_devlink: Stop trying to optimize cycle detection logic 2024-12-09T09:41:03+00:00 Saravana Kannan saravanak@google.com 2024-10-30T17:10:07+00:00 d34bf994bb973db1d142376e555e093c3146f730 commit bac3b10b78e54b7da3cede397258f75a2180609b upstream. In attempting to optimize fw_devlink runtime, I introduced numerous cycle detection bugs by foregoing cycle detection logic under specific conditions. Each fix has further narrowed the conditions for optimization. It's time to give up on these optimization attempts and just run the cycle detection logic every time fw_devlink tries to create a device link. The specific bug report that triggered this fix involved a supplier fwnode that never gets a device created for it. Instead, the supplier fwnode is represented by the device that corresponds to an ancestor fwnode. In this case, fw_devlink didn't do any cycle detection because the cycle detection logic is only run when a device link is created between the devices that correspond to the actual consumer and supplier fwnodes. With this change, fw_devlink will run cycle detection logic even when creating SYNC_STATE_ONLY proxy device links from a device that is an ancestor of a consumer fwnode. Reported-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com> Closes: https://lore.kernel.org/all/1a1ab663-d068-40fb-8c94-f0715403d276@ideasonboard.com/ Fixes: 6442d79d880c ("driver core: fw_devlink: Improve detection of overlapping cycles") Cc: stable <stable@kernel.org> Tested-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com> Signed-off-by: Saravana Kannan <saravanak@google.com> Link: https://lore.kernel.org/r/20241030171009.1853340-1-saravanak@google.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit bac3b10b78e54b7da3cede397258f75a2180609b upstream.

In attempting to optimize fw_devlink runtime, I introduced numerous cycle
detection bugs by foregoing cycle detection logic under specific
conditions. Each fix has further narrowed the conditions for optimization.

It's time to give up on these optimization attempts and just run the cycle
detection logic every time fw_devlink tries to create a device link.

The specific bug report that triggered this fix involved a supplier fwnode
that never gets a device created for it. Instead, the supplier fwnode is
represented by the device that corresponds to an ancestor fwnode.

In this case, fw_devlink didn't do any cycle detection because the cycle
detection logic is only run when a device link is created between the
devices that correspond to the actual consumer and supplier fwnodes.

With this change, fw_devlink will run cycle detection logic even when
creating SYNC_STATE_ONLY proxy device links from a device that is an
ancestor of a consumer fwnode.

Reported-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Closes: https://lore.kernel.org/all/1a1ab663-d068-40fb-8c94-f0715403d276@ideasonboard.com/
Fixes: 6442d79d880c ("driver core: fw_devlink: Improve detection of overlapping cycles")
Cc: stable <stable@kernel.org>
Tested-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Signed-off-by: Saravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20241030171009.1853340-1-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Merge tag 'driver-core-6.12-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core 2024-11-03T18:51:53+00:00 Linus Torvalds torvalds@linux-foundation.org 2024-11-03T18:51:53+00:00 886b7e80ab19841f640cafd8b5ab053409b9b931 Pull driver core revert from Greg KH: "Here is a single driver core revert for 6.12-rc6. It reverts a change that came in -rc1 that was supposed to resolve a reported problem, but caused another one, so revert it for now so that we can get this all worked out properly in 6.13. The revert has been in linux-next all week with no reported issues" * tag 'driver-core-6.12-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: Revert "driver core: Fix uevent_show() vs driver detach race" 
Pull driver core revert from Greg KH:
 "Here is a single driver core revert for 6.12-rc6. It reverts a change
  that came in -rc1 that was supposed to resolve a reported problem, but
  caused another one, so revert it for now so that we can get this all
  worked out properly in 6.13.

  The revert has been in linux-next all week with no reported issues"

* tag 'driver-core-6.12-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core:
  Revert "driver core: Fix uevent_show() vs driver detach race"
Revert "driver core: Fix uevent_show() vs driver detach race" 2024-10-29T00:23:43+00:00 Greg Kroah-Hartman gregkh@linuxfoundation.org 2024-10-29T00:23:04+00:00 9a71892cbcdb9d1459c84f5a4c722b14354158a5 This reverts commit 15fffc6a5624b13b428bb1c6e9088e32a55eb82c. This commit causes a regression, so revert it for now until it can come back in a way that works for everyone. Link: https://lore.kernel.org/all/172790598832.1168608.4519484276671503678.stgit@dwillia2-xfh.jf.intel.com/ Fixes: 15fffc6a5624 ("driver core: Fix uevent_show() vs driver detach race") Cc: stable <stable@kernel.org> Cc: Ashish Sangwan <a.sangwan@samsung.com> Cc: Namjae Jeon <namjae.jeon@samsung.com> Cc: Dirk Behme <dirk.behme@de.bosch.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Rafael J. Wysocki <rafael@kernel.org> Cc: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
This reverts commit 15fffc6a5624b13b428bb1c6e9088e32a55eb82c.

This commit causes a regression, so revert it for now until it can come
back in a way that works for everyone.

Link: https://lore.kernel.org/all/172790598832.1168608.4519484276671503678.stgit@dwillia2-xfh.jf.intel.com/
Fixes: 15fffc6a5624 ("driver core: Fix uevent_show() vs driver detach race")
Cc: stable <stable@kernel.org>
Cc: Ashish Sangwan <a.sangwan@samsung.com>
Cc: Namjae Jeon <namjae.jeon@samsung.com>
Cc: Dirk Behme <dirk.behme@de.bosch.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>