A lockdep warning is reported in gpiolib-cdev driver:
WARNING: drivers/gpio/gpiolib-cdev.c:2735 at
gpiolib_cdev_register+0x114/0x140, CPU#1: swapper/0/1
Modules linked in:
CPU: 1 UID: 0 PID: 1 Comm: swapper/0 Not tainted
7.0.0-rc1-next-20260227-00065-g6af4b9cfeded #12259 PREEMPT
Hardware name: Samsung Exynos (Flattened Device Tree)
Call trace:
unwind_backtrace from show_stack+0x10/0x14
show_stack from dump_stack_lvl+0x68/0x88
dump_stack_lvl from __warn+0x94/0x210
__warn from warn_slowpath_fmt+0x1b0/0x1bc
warn_slowpath_fmt from gpiolib_cdev_register+0x114/0x140
gpiolib_cdev_register from gpiochip_setup_dev+0x4c/0xd0
gpiochip_setup_dev from gpiochip_add_data_with_key+0x960/0xad4
gpiochip_add_data_with_key from devm_gpiochip_add_data_with_key+0x20/0x5c
This is because the SRCU wasn't held in gpiolib_cdev_register() when the
caller is from gpiochip_add_data_with_key() instead of
gpiochip_setup_devs(). gpiochip_sysfs_register() shares the similar
concern.
Given that both gpiolib_cdev_register() and gpiochip_sysfs_register()
are only called from gpiolib but no external users. Remove the lockdep
checks to fix the warnings.
Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Closes: https://lore.kernel.org/all/506ce9b3-d492-4fce-9d02-330e411911e2@samsung.com/
Fixes: cf674f1a0c ("gpio: Ensure struct gpio_chip for gpiochip_setup_dev()")
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://patch.msgid.link/20260228131430.102388-1-tzungbi@kernel.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
Ensure struct gpio_chip for gpiochip_setup_dev(). This eliminates a few
checks for struct gpio_chip.
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
Link: https://patch.msgid.link/20260223061726.82161-5-tzungbi@kernel.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
gpiochip_sysfs_unregister() is only called by gpiochip_remove() where
the struct gpio_chip is ensured.
Remove the redundant check.
Reviewed-by: Linus Walleij <linusw@kernel.org>
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
Link: https://patch.msgid.link/20260223061726.82161-4-tzungbi@kernel.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
This was done entirely with mindless brute force, using
git grep -l '\<k[vmz]*alloc_objs*(.*, GFP_KERNEL)' |
xargs sed -i 's/\(alloc_objs*(.*\), GFP_KERNEL)/\1)/'
to convert the new alloc_obj() users that had a simple GFP_KERNEL
argument to just drop that argument.
Note that due to the extreme simplicity of the scripting, any slightly
more complex cases spread over multiple lines would not be triggered:
they definitely exist, but this covers the vast bulk of the cases, and
the resulting diff is also then easier to check automatically.
For the same reason the 'flex' versions will be done as a separate
conversion.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is the result of running the Coccinelle script from
scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to
avoid scalar types (which need careful case-by-case checking), and
instead replace kmalloc-family calls that allocate struct or union
object instances:
Single allocations: kmalloc(sizeof(TYPE), ...)
are replaced with: kmalloc_obj(TYPE, ...)
Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...)
are replaced with: kmalloc_objs(TYPE, COUNT, ...)
Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...)
are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...)
(where TYPE may also be *VAR)
The resulting allocations no longer return "void *", instead returning
"TYPE *".
Signed-off-by: Kees Cook <kees@kernel.org>
Currently if we export a GPIO over sysfs and unbind the parent GPIO
controller, the exported attribute will remain under /sys/class/gpio
because once we remove the parent device, we can no longer associate the
descriptor with it in gpiod_unexport() and never drop the final
reference.
Rework the teardown code: provide an unlocked variant of
gpiod_unexport() and remove all exported GPIOs with the sysfs_lock taken
before unregistering the parent device itself. This is done to prevent
any new exports happening before we unregister the device completely.
Cc: stable@vger.kernel.org
Fixes: 1cd53df733 ("gpio: sysfs: don't look up exported lines as class devices")
Link: https://patch.msgid.link/20260212133505.81516-1-bartosz.golaszewski@oss.qualcomm.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
This function takes a GPIO descriptor as first argument. Make its naming
consistent with the rest of the GPIO codebase and use the gpiod_ prefix.
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Andrew Jeffery <andrew@codeconstruct.com.au>
Link: https://lore.kernel.org/r/20251016-aspeed-gpiolib-include-v1-1-31201c06d124@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
The chip_$level() macros take struct gpio_chip as argument so make it
follow the convention of using the 'gpiochip_' prefix.
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
While these flags are private within drivers/gpio/, when looking at the
code, it's not really clear they are GPIO-specific. Since these are GPIO
descriptor flags, prepend their names with a common "GPIOD" prefix.
While at it: update the flags' docs: make spelling consistent, correct
outdated information, etc.
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250909-rename-gpio-flags-v1-1-bda208a40856@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
The test for "if (!desc_data)" does not work correctly because the list
iterator in a list_for_each_entry() loop is always non-NULL. If we don't
exit via a break, then it points to invalid memory. Instead, use a tmp
variable for the list iterator and only set the "desc_data" when we have
found a match.
Fixes: 1cd53df733 ("gpio: sysfs: don't look up exported lines as class devices")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://lore.kernel.org/r/747545bf-05f0-4f89-ba77-cb96bf9041f1@sabinyo.mountain
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Add a Kconfig switch allowing to disable the legacy parts of the GPIO
sysfs interface. This means that even though we keep the
/sys/class/gpio/ directory, it no longer contains the global
export/unexport attribute pair (instead, the user should use the
per-chip export/unpexport) nor the gpiochip$BASE entries. This option
default to y if GPIO sysfs is enabled but we'll default it to n at some
point in the future.
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250704-gpio-sysfs-chip-export-v4-9-9289d8758243@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
As a way to allow the user-space to stop referring to GPIOs by their
global numbers, introduce a parallel group of line attributes for
exported GPIO that live inside the GPIO chip class device and are
referred to by their HW offset within their parent chip.
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250704-gpio-sysfs-chip-export-v4-8-9289d8758243@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
In preparation for adding a parallel, per-chip attribute group for
exported GPIO lines, stop using class device APIs to refer to it in the
code. When unregistering the chip, don't call class_find_device() but
instead store exported lines in a linked list inside the GPIO chip data
object and look it up there.
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250704-gpio-sysfs-chip-export-v4-7-9289d8758243@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Currently each exported GPIO is represented in sysfs as a separate class
device. This allows us to simply use dev_get_drvdata() to retrieve the
pointer passed to device_create_with_groups() from sysfs ops callbacks.
However, we're preparing to add a parallel set of per-line sysfs
attributes that will live inside the associated gpiochip group. They are
not registered as class devices and so have the parent device passed as
argument to their callbacks (the GPIO chip class device).
Put the attribute structs inside the GPIO descriptor data and
dereference the relevant ones using container_of() in the callbacks.
This way, we'll be able to reuse the same code for both the legacy and
new GPIO attributes.
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250704-gpio-sysfs-chip-export-v4-6-9289d8758243@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
In preparation for future commits which will make use of descriptor AND
GPIO-device data in the same functions rename the former from data to
desc_data separately which will make future changes smaller and easier
to read.
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250704-gpio-sysfs-chip-export-v4-5-9289d8758243@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
We don't use any fields from struct device in gpio_sysfs_request_irq(),
gpio_sysfs_free_irq() and gpio_sysfs_set_active_low(). We only use the
dev argument to get the associated struct gpiod_data pointer with
dev_get_drvdata().
To make the transition to not using dev_get_drvdata() across line
callbacks for sysfs attributes easier, pass gpiod_data directly to
these functions instead of having it wrapped in struct device.
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250704-gpio-sysfs-chip-export-v4-4-9289d8758243@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
There's no reason to retrieve the reference to the sysfs dirent every
time we request an interrupt, we can as well only do it once when
exporting the GPIO.
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250704-gpio-sysfs-chip-export-v4-3-9289d8758243@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
In order to enable moving away from the global GPIO numberspace-based
exporting of lines over sysfs: add a parallel, per-chip entry under
/sys/class/gpio/ for every registered GPIO chip, denoted by device ID
in the file name and not its base GPIO number.
Compared to the existing chip group: it does not contain the "base"
attribute as the goal of this change is to not refer to GPIOs by their
global number from user-space anymore. It also contains its own,
per-chip export/unexport attribute pair which allow to export lines by
their hardware offset within the chip.
Caveat #1: the new device cannot be a link to (or be linked to by) the
existing "gpiochip<BASE>" entry as we cannot create links in
/sys/class/xyz/.
Caveat #2: the new entry cannot be named "gpiochipX" as it could
conflict with devices whose base is statically defined to a low number.
Let's go with "chipX" instead.
While at it: the chip label is unique so update the untrue statement
when extending the docs.
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250704-gpio-sysfs-chip-export-v4-2-9289d8758243@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
We have a dedicated comparator for GPIO descriptors that performs
additional checks and hides the implementation detail of whether the
same GPIO can be associated with two separate struct gpio_desc objects.
Use it in sysfs code
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250704-gpio-sysfs-chip-export-v4-1-9289d8758243@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
When invoking device_create_with_groups(), its return value is stored
in `data->cdev_base`. However, in case of faiure, `data` is first freed
and then derefernced in order to return `data->cdev_base`.
Fix the use-after-free by extracting the error code before free'ing
`data`.
Fixes: fd19792851 ("gpio: sysfs: remove the mockdev pointer from struct gpio_device")
Addresses-Coverity-ID: 1644512 ("Memory - illegal accesses (USE_AFTER_FREE)")
Signed-off-by: Antonio Quartulli <antonio@mandelbit.com>
Link: https://lore.kernel.org/r/20250622220221.28025-1-antonio@mandelbit.com
[Bartosz: added Fixes: tag, tweaked commit message]
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
The usage of the mockdev pointer in struct gpio_device is limited to the
GPIO sysfs code. There's no reason to keep it in this top-level
structure. Create a separate structure containing the reference to the
GPIO device and the dummy class device that will be passed to
device_create_with_groups(). The !gdev->mockdev checks can be removed as
long as we make sure that all operations on the GPIO class are protected
with the sysfs lock.
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250610-gpio-sysfs-chip-export-v1-6-a8c7aa4478b1@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
No symbols from the linux/idr.h or linux/spinlock.h headers are used in
this file so remove them. We also don't technically need linux/list.h
currently but one of the follow-up commits will start using it so let's
leave it.
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250610-gpio-sysfs-chip-export-v1-5-a8c7aa4478b1@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Update the code to be more consistent with the rest of the codebase.
Mostly correctly align line-breaks, remove unneeded tabs, stray newlines
& spaces and tweak the comment style.
No functional change.
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250610-gpio-sysfs-chip-export-v1-4-a8c7aa4478b1@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
While not critical, it's useful to have the corresponding call to
mutex_destroy() whenever we use mutex_init(). Add the call right before
kfreeing the GPIO data.
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250610-gpio-sysfs-chip-export-v1-3-a8c7aa4478b1@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Some drivers as well as the character device and sysfs code check
whether the line actually is in output mode before allowing the user to
set a value.
However, GPIO value setters now return integer values and can indicate
failures. This allows us to move these checks into the core code.
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250311-gpio-set-check-output-v1-1-d971bca9e6fa@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
In order to emit line-state events on edge changes in sysfs, update the
EDGE flags in the descriptor in gpio_sysfs_request_irq() and emit the
event on a successful store.
Reviewed-by: Kent Gibson <warthog618@gmail.com>
Link: https://lore.kernel.org/r/20241031-gpio-notify-sysfs-v4-5-142021c2195c@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
The sysfs active_low attribute doesn't go through the usual paths so it
doesn't emit the line-state event. Add the missing call to
gpiod_line_state_notify() to gpio_sysfs_set_active_low().
Reviewed-by: Kent Gibson <warthog618@gmail.com>
Link: https://lore.kernel.org/r/20241031-gpio-notify-sysfs-v4-4-142021c2195c@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
We already emit a CONFIG_RELEASED event when a line is unexported over
sysfs (this is handled by gpiod_free()) but we don't do the opposite
when it's exported. This adds the missing call to
gpiod_line_state_notify().
Reviewed-by: Kent Gibson <warthog618@gmail.com>
Link: https://lore.kernel.org/r/20241031-gpio-notify-sysfs-v4-3-142021c2195c@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
We should not emit a non-ratelimited warning everytime a user passes an
invalid value to /sys/class/gpio/export as it's an easy way to spam the
kernel log. Change the relevant messages to pr_debug_ratelimited().
Link: https://lore.kernel.org/r/20241021185717.96449-1-brgl@bgdev.pl
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
All class functions used here take a const pointer to the class
structure. We can constify gpio_class.
While at it: remove a stray newline and use a tab in the struct
definition for consistency with the line above.
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20241014121831.106532-1-brgl@bgdev.pl
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
For drivers or board files that set gpio_chip->names, the links to the
GPIO attribute group created on sysfs export will be named after the
line's name set in that array. For lines that are named using device
properties, the names pointer of the gpio_chip struct is never assigned
so they are exported as if they're not named.
The ABI documentation does not mention the former behavior and given
that the majority of modern systems use device-tree, ACPI or other way
of passing GPIO names using device properties - bypassing gc->names -
it's better to make the behavior consistent by always exporting lines as
"gpioXYZ".
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20240930083029.17694-1-brgl@bgdev.pl
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
$ scripts/kernel-doc -v -none -Wall drivers/gpio/gpiolib* 2>&1 | grep -w warning | wc -l
67
Fix these by adding Return sections. While at it, make sure all of
Return sections use the same style.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240828164449.2777666-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
In the cases when gpio_is_valid() is called with unsigned parameter
the result is always true in the GPIO library code, hence the check
for false won't ever be true. Get rid of such calls.
While at it, move GPIO device base to be unsigned to clearly show
it won't ever be negative. This requires a new definition for the
maximum GPIO number in the system.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
It would make sense to return -EPERM if the bit was already set (already
used), not if it was cleared. Before this fix pins can only be exported on
the 2nd attempt:
$ echo 522 > /sys/class/gpio/export
sh: write error: Operation not permitted
$ echo 522 > /sys/class/gpio/export
Fixes: 35b545332b ("gpio: remove gpio_lock")
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Lockdep with CONFIG_PROVE_RCU enabled reports false positives about
suspicious rcu_dereference() usage. Let's silence it by using
srcu_dereference() which is the correct helper with SRCU.
Fixes: d83cee3d2b ("gpio: protect the pointer to gpio_chip in gpio_device with SRCU")
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202402122234.d85cca9b-lkp@intel.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Ensure we cannot crash if the GPIO device gets unregistered (and the
chip pointer set to NULL) during any of the API calls.
To that end: wait for all users of gdev->chip to exit their read-only
SRCU critical sections in gpiochip_remove().
For brevity: add a guard class which can be instantiated at the top of
every function requiring read-only access to the chip pointer and use it
in all API calls taking a GPIO descriptor as argument. In places where
we only deal with the GPIO device - use regular guard() helpers and
rcu_dereference() for chip access. Do the same in API calls taking a
const pointer to gpio_desc.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Don't dereference gdev->chip if the same information can be obtained
from struct gpio_device.
Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
We're working towards protecting the chip pointer in struct gpio_device
with SRCU. In order to use it in sysfs callbacks we must pass the pointer
to the GPIO device that wraps the chip instead of the address of the
chip itself as the user data.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Checking the gdev->mockdev pointer for NULL must be part of the critical
section.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
The "multi-function" gpio_lock is pretty much useless with how it's used
in GPIOLIB currently. Because many GPIO API calls can be called from all
contexts but may also call into sleeping driver callbacks, there are
many places with utterly broken workarounds like yielding the lock to
call a possibly sleeping function and then re-acquiring it again without
taking into account that the protected state may have changed.
It was also used to protect several unrelated things: like individual
descriptors AND the GPIO device list. We now serialize access to these
two with SRCU and so can finally remove the spinlock.
There is of course the question of consistency of lockless access to
GPIO descriptors. Because we only support exclusive access to GPIOs
(officially anyway, I'm looking at you broken
GPIOD_FLAGS_BIT_NONEXCLUSIVE bit...) and the API contract with providers
does not guarantee serialization, it's enough to ensure we cannot
accidentally dereference an invalid pointer and that the state we present
to both users and providers remains consistent. To achieve that: read the
flags field atomically except for a few special cases. Read their current
value before executing callback code and use this value for any subsequent
logic. Modifying the flags depends on the particular use-case and can
differ. For instance: when requesting a GPIO, we need to set the
REQUESTED bit immediately so that the next user trying to request the
same line sees -EBUSY.
While at it: the allocations that used GFP_ATOMIC until this point can
now switch to GFP_KERNEL.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
With the list of GPIO devices now protected with SRCU we can use
gpio_device_find() to traverse it from sysfs.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
This reverts commits 1979a28075 ("gpiolib: replace the GPIO device
mutex with a read-write semaphore") and 65a828bab1 ("gpiolib: use
a mutex to protect the list of GPIO devices").
Unfortunately the legacy GPIO API that's still used in older code has to
translate numbers from the global GPIO numberspace to descriptors. This
results in a GPIO device lookup in every call to legacy functions. Some
of those functions - like gpio_set/get_value() - can be called from
atomic context so taking a sleeping lock that is an RW semaphore results
in an error.
We'll probably have to protect this list with SRCU.
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/linux-wireless/f7b5ff1e-8f34-4d98-a7be-b826cb897dc8@moroto.mountain/
Fixes: 1979a28075 ("gpiolib: replace the GPIO device mutex with a read-write semaphore")
Fixes: 65a828bab1 ("gpiolib: use a mutex to protect the list of GPIO devices")
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
There are only two spots where we modify (add to or remove objects from)
the GPIO device list. Readers should be able to access it concurrently.
Replace the mutex with a read-write semaphore and adjust the locking
operations accordingly.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Older code has an annoying habit of putting tabs between the type and the
name of the variable. This doesn't really add to readability and newer
code doesn't do it so make the entire file consistent.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
The global list of GPIO devices is never modified or accessed from
atomic context so it's fine to protect it using a mutex. Add a new
global lock dedicated to the gpio_devices list and use it whenever
accessing or modifying it.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
If gpio_set_transitory() fails, we should free the GPIO again. Most
notably, the flag FLAG_REQUESTED has previously been set in
gpiod_request_commit(), and should be reset on failure.
To my knowledge, this does not affect any current users, since the
gpio_set_transitory() mainly returns 0 and -ENOTSUPP, which is converted
to 0. However the gpio_set_transitory() function calles the .set_config()
function of the corresponding GPIO chip and there are some GPIO drivers in
which some (unlikely) branches return other values like -EPROBE_DEFER,
and -EINVAL. In these cases, the above mentioned FLAG_REQUESTED would not
be reset, which results in the pin being blocked until the next reboot.
Fixes: e10f72bf4b ("gpio: gpiolib: Generalise state persistence beyond sleep")
Signed-off-by: Boerge Struempfel <boerge.struempfel@gmail.com>
Reviewed-by: Andy Shevchenko <andy@kernel.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
