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In `gpiod_get_label()`, it is possible that `srcu_dereference_check()` may
return a NULL pointer, leading to a scenario where `label->str` is accessed
without verifying if `label` itself is NULL.
This patch adds a proper NULL check for `label` before accessing
`label->str`. The check for `label->str != NULL` is removed because
`label->str` can never be NULL if `label` is not NULL.
This fixes the issue where the label name was being printed as `(efault)`
when dumping the sysfs GPIO file when `label == NULL`.
Fixes: 5a646e03e956 ("gpiolib: Return label, if set, for IRQ only line")
Fixes: a86d27693066 ("gpiolib: fix the speed of descriptor label setting with SRCU")
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Link: https://lore.kernel.org/r/20241003131351.472015-1-prabhakar.mahadev-lad.rj@bp.renesas.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
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If we remove a GPIO chip that is also an interrupt controller with users
not having freed some interrupts, we'll end up leaking resources as
indicated by the following warning:
remove_proc_entry: removing non-empty directory 'irq/30', leaking at least 'gpio'
As there's no way of notifying interrupt users about the irqchip going
away and the interrupt subsystem is not plugged into the driver model and
so not all cases can be handled by devlinks, we need to make sure to free
all interrupts before the complete the removal of the provider.
Reviewed-by: Herve Codina <herve.codina@bootlin.com>
Tested-by: Herve Codina <herve.codina@bootlin.com>
Link: https://lore.kernel.org/r/20240919135104.3583-1-brgl@bgdev.pl
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
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$ 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>
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Use the IS_ERR_OR_NULL() helper instead of open-coding a
NULL and an error pointer checks to simplify the code and
improve readability.
No functional changes are intended.
Signed-off-by: Hongbo Li <lihongbo22@huawei.com>
Link: https://lore.kernel.org/r/20240828122039.3697037-1-lihongbo22@huawei.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
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There is no need to have and export the count variable for the array
in question. Instead, make it NULL-terminated.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240819142945.327808-6-andriy.shevchenko@linux.intel.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core
Pull driver core updates from Greg KH:
"Here is the big set of driver core changes for 6.11-rc1.
Lots of stuff in here, with not a huge diffstat, but apis are evolving
which required lots of files to be touched. Highlights of the changes
in here are:
- platform remove callback api final fixups (Uwe took many releases
to get here, finally!)
- Rust bindings for basic firmware apis and initial driver-core
interactions.
It's not all that useful for a "write a whole driver in rust" type
of thing, but the firmware bindings do help out the phy rust
drivers, and the driver core bindings give a solid base on which
others can start their work.
There is still a long way to go here before we have a multitude of
rust drivers being added, but it's a great first step.
- driver core const api changes.
This reached across all bus types, and there are some fix-ups for
some not-common bus types that linux-next and 0-day testing shook
out.
This work is being done to help make the rust bindings more safe,
as well as the C code, moving toward the end-goal of allowing us to
put driver structures into read-only memory. We aren't there yet,
but are getting closer.
- minor devres cleanups and fixes found by code inspection
- arch_topology minor changes
- other minor driver core cleanups
All of these have been in linux-next for a very long time with no
reported problems"
* tag 'driver-core-6.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (55 commits)
ARM: sa1100: make match function take a const pointer
sysfs/cpu: Make crash_hotplug attribute world-readable
dio: Have dio_bus_match() callback take a const *
zorro: make match function take a const pointer
driver core: module: make module_[add|remove]_driver take a const *
driver core: make driver_find_device() take a const *
driver core: make driver_[create|remove]_file take a const *
firmware_loader: fix soundness issue in `request_internal`
firmware_loader: annotate doctests as `no_run`
devres: Correct code style for functions that return a pointer type
devres: Initialize an uninitialized struct member
devres: Fix memory leakage caused by driver API devm_free_percpu()
devres: Fix devm_krealloc() wasting memory
driver core: platform: Switch to use kmemdup_array()
driver core: have match() callback in struct bus_type take a const *
MAINTAINERS: add Rust device abstractions to DRIVER CORE
device: rust: improve safety comments
MAINTAINERS: add Danilo as FIRMWARE LOADER maintainer
MAINTAINERS: add Rust FW abstractions to FIRMWARE LOADER
firmware: rust: improve safety comments
...
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In the match() callback, the struct device_driver * should not be
changed, so change the function callback to be a const *. This is one
step of many towards making the driver core safe to have struct
device_driver in read-only memory.
Because the match() callback is in all busses, all busses are modified
to handle this properly. This does entail switching some container_of()
calls to container_of_const() to properly handle the constant *.
For some busses, like PCI and USB and HV, the const * is cast away in
the match callback as those busses do want to modify those structures at
this point in time (they have a local lock in the driver structure.)
That will have to be changed in the future if they wish to have their
struct device * in read-only-memory.
Cc: Rafael J. Wysocki <rafael@kernel.org>
Reviewed-by: Alex Elder <elder@kernel.org>
Acked-by: Sumit Garg <sumit.garg@linaro.org>
Link: https://lore.kernel.org/r/2024070136-wrongdoer-busily-01e8@gregkh
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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This function has been deprecated for some time and is now only used
within the GPIOLIB core. Remove it from the public header and unexport
it as all current users are linked against the compilation unit where
it is defined.
Link: https://lore.kernel.org/r/20240625073815.12376-1-brgl@bgdev.pl
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
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The gpio_suffixes array is defined in the gpiolib.h header. This means
the array is stored in .rodata of every compilation unit that includes
it. Put the definition for the array in gpiolib.c and export just the
symbol in the header. We need the size of the array so expose it too.
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Link: https://lore.kernel.org/r/20240612184821.58053-1-brgl@bgdev.pl
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
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Show more info for interrupt only lines in debugfs. It's useful
to monitor the lines that have been never requested as GPIOs,
but IRQs.
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240530191418.1138003-3-andriy.shevchenko@linux.intel.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
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If line has been locked as IRQ without requesting,
still check its label and return it, if not NULL.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240530191418.1138003-2-andriy.shevchenko@linux.intel.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
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gpiochip_set_desc_names() cannot fail so drop its return value.
Link: https://lore.kernel.org/r/20240527194613.197810-1-brgl@bgdev.pl
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
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Userspace may trigger a speculative read of an address outside the gpio
descriptor array.
Users can do that by calling gpio_ioctl() with an offset out of range.
Offset is copied from user and then used as an array index to get
the gpio descriptor without sanitization in gpio_device_get_desc().
This change ensures that the offset is sanitized by using
array_index_nospec() to mitigate any possibility of speculative
information leaks.
This bug was discovered and resolved using Coverity Static Analysis
Security Testing (SAST) by Synopsys, Inc.
Signed-off-by: Hagar Hemdan <hagarhem@amazon.com>
Link: https://lore.kernel.org/r/20240523085332.1801-1-hagarhem@amazon.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux
Pull gpio updates from Bartosz Golaszewski
"This was a quiet release cycle for the GPIO tree and so this
pull-request is relatively small.
We have one new driver, some minor improvements to the GPIO core code
and across several drivers, some DT and documentation updates but in
general nothing stands out or is controversial. All changes have spent
time in next with no reported issues (or ones that were quickly
fixed).
GPIO core:
- remove more unused legacy interfaces (after converting the last
remaining users to better alternatives)
- update kerneldocs
- improve error handling and log messages in GPIO ACPI code
- remove dead code (always true checks) from GPIOLIB
New drivers:
- add a driver for Intel Granite Rapids-D vGPIO
Driver improvements:
- use -ENOTSUPP consistently in gpio-regmap and gpio-pcie-idio-24
- provide an ID table for gpio-cros-ec to avoid a driver name
fallback check
- add support for gpio-ranges for GPIO drivers supporting multiple
GPIO banks
- switch to using dynamic GPIO base in gpio-brcmstb
- fix irq handling in gpio-npcm-sgpio
- switch to memory mapped IO accessors in gpio-sch
DT bindings:
- add support for gpio-ranges to gpio-brcmstb
- add support for a new model and the gpio-line-names property to
gpio-mpfs
Documentation:
- replace leading tabs with spaces in code blocks
- fix typos"
* tag 'gpio-updates-for-v6.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux: (30 commits)
gpio: nuvoton: Fix sgpio irq handle error
gpiolib: Discourage to use formatting strings in line names
gpio: brcmstb: add support for gpio-ranges
gpio: of: support gpio-ranges for multiple gpiochip devices
dt-bindings: gpio: brcmstb: add gpio-ranges
gpio: Add Intel Granite Rapids-D vGPIO driver
gpio: brcmstb: Use dynamic GPIO base numbers
gpiolib: acpi: Set label for IRQ only lines
gpiolib: acpi: Add fwnode name to the GPIO interrupt label
gpiolib: Get rid of never false gpio_is_valid() calls
gpiolib: acpi: Pass con_id instead of property into acpi_dev_gpio_irq_get_by()
gpiolib: acpi: Move acpi_can_fallback_to_crs() out of __acpi_find_gpio()
gpiolib: acpi: Simplify error handling in __acpi_find_gpio()
gpiolib: acpi: Extract __acpi_find_gpio() helper
gpio: sch: Utilise temporary variable for struct device
gpio: sch: Switch to memory mapped IO accessors
gpio: regmap: Use -ENOTSUPP consistently
gpio: pcie-idio-24: Use -ENOTSUPP consistently
Documentation: gpio: Replace leading TABs by spaces in code blocks
gpiolib: acpi: Check for errors first in acpi_find_gpio()
...
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We used a per-descriptor SRCU struct in order to not impose a wait with
synchronize_srcu() for descriptor X on read-only operations of
descriptor Y. Now that we no longer call synchronize_srcu() on
descriptor label change but only when releasing descriptor resources, we
can use a single SRCU structure for all GPIO descriptors in a given chip.
Suggested-by: "Paul E. McKenney" <paulmck@kernel.org>
Acked-by: "Paul E. McKenney" <paulmck@kernel.org>
Link: https://lore.kernel.org/r/20240507172414.28513-1-brgl@bgdev.pl
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
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Commit 1f2bcb8c8ccd ("gpio: protect the descriptor label with SRCU")
caused a massive drop in performance of requesting GPIO lines due to the
call to synchronize_srcu() on each label change. Rework the code to not
wait until all read-only users are done with reading the label but
instead atomically replace the label pointer and schedule its release
after all read-only critical sections are done.
To that end wrap the descriptor label in a struct that also contains the
rcu_head struct required for deferring tasks using call_srcu() and stop
using kstrdup_const() as we're required to allocate memory anyway. Just
allocate enough for the label string and rcu_head in one go.
Reported-by: Neil Armstrong <neil.armstrong@linaro.org>
Closes: https://lore.kernel.org/linux-gpio/CAMRc=Mfig2oooDQYTqo23W3PXSdzhVO4p=G4+P8y1ppBOrkrJQ@mail.gmail.com/
Fixes: 1f2bcb8c8ccd ("gpio: protect the descriptor label with SRCU")
Suggested-by: "Paul E. McKenney" <paulmck@kernel.org>
Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8650-QRD
Acked-by: "Paul E. McKenney" <paulmck@kernel.org>
Link: https://lore.kernel.org/r/20240507121346.16969-1-brgl@bgdev.pl
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
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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>
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We are going to remove legacy API from kernel, don't mention
it in the code that does not use it already for a while.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
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kobject_get() errors
When a gpiochip gets added by loading a module, then another driver may
be waiting for that gpiochip to load on the deferred-probe list.
If the deferred-probe for the consumer of gpiochip then triggers between
the gpiodev_add_to_list_unlocked() calls which makes gpio_device_find()
see the chip and the gpiochip_setup_dev() later then gpio_device_find()
does a kobject_get() on an uninitialized kobject since the kobject is
initialized by gpiochip_setup_dev() calling device_initialize():
arizona spi-10WM5102:00: cannot find GPIO chip arizona, deferring
arizona spi-10WM5102:00: cannot find GPIO chip arizona, deferring
------------[ cut here ]------------
kobject: 'gpiochip5' (00000000241466f2): is not initialized, yet kobject_get() is being called.
WARNING: CPU: 3 PID: 42 at lib/kobject.c:640 kobject_get+0x43/0x70
Call Trace:
kobject_get
gpio_device_find
gpiod_find_and_request
gpiod_get
snd_byt_wm5102_mc_probe
Not only is the device not initialized yet, but when the gpio-device is
added to the list things like the irqchip also have not been initialized
yet.
So gpio_device_find() should really ignore the gpio-device until
gpiochip_add_data_with_key() is fully done. Add a device_is_registered()
check to gpio_device_find() to ignore gpio-devices on the list which are
not yet fully initialized.
Fixes: aab5c6f20023 ("gpio: set device type for GPIO chips")
Suggested-by: Bartosz Golaszewski <brgl@bgdev.pl>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Andy Shevchenko <andy@kernel.org>
[Bartosz: fix a typo in commit message]
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
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When gpio-ranges property was missed to be added in the gpio node,
using dev_err() to show an error message will helping to locate issues
easier.
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
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When consolidating GPIO lookups in ACPI code, the debug messaging
had been reworked that the user may see
[ 13.401147] (NULL device *): using ACPI '\_SB.LEDS.led-0' for '(null)' GPIO lookup
[ 13.401378] gpio gpiochip0: Persistence not supported for GPIO 40
[ 13.401402] gpio-40 (?): no flags found for (null)
instead of
[ 14.182962] gpio gpiochip0: Persistence not supported for GPIO 40
[ 14.182994] gpio-40 (?): no flags found for gpios
The '(null)' parts are less informative and likely scare the users.
Replace them by '(default)' which can point out to the default connection
IDs, such as 'gpios'.
While at it, amend other places where con_id is used in the messages.
Reported-by: Ferry Toth <ftoth@exalondelft.nl>
Fixes: 8eb1f71e7acc ("gpiolib: consolidate GPIO lookups")
Suggested-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Tested-by: Ferry Toth <ftoth@exalondelft.nl>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
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There is no need to repeat for-loop twice in the error path in
gpiochip_add_data_with_key(). Deduplicate it. While at it,
rename loop variable to be more specific and avoid ambguity.
It also properly unwinds the SRCU, i.e. in reversed order of allocating.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
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Linux 6.8-rc7
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Hogs are added *after* ACPI so should be removed *before* in error path.
Fixes: a411e81e61df ("gpiolib: add hogs support for machine code")
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
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Make acpi_gpio_count() take firmware node as a parameter in order
to be aligned with other functions and decouple from unused device
pointer. The latter helps to create a common fwnode_gpio_count()
in the future.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
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Make of_gpio_get_count() take firmware node as a parameter in order
to be aligned with other functions and decouple from unused device
pointer. The latter helps to create a common fwnode_gpio_count()
in the future.
While at it, rename to be of_gpio_count() to be aligned with the others.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
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After shuffling the code, error path wasn't updated correctly.
Fix it here.
Fixes: 2f4133bb5f14 ("gpiolib: No need to call gpiochip_remove_pin_ranges() twice")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
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This devm API takes a consumer device as an argument to setup the devm
action, but throws it away when calling further into gpiolib. This leads
to odd debug messages like this:
(NULL device *): using DT '/gpio-keys/switch-pen-insert' for '(null)' GPIO lookup
Let's pass the consumer device down, by directly calling what
fwnode_gpiod_get_index() calls but pass the device used for devm. This
changes the message to look like this instead:
gpio-keys gpio-keys: using DT '/gpio-keys/switch-pen-insert' for '(null)' GPIO lookup
Note that callers of fwnode_gpiod_get_index() will still see the NULL
device pointer debug message, but there's not much we can do about that
because the API doesn't take a struct device.
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Fixes: 8eb1f71e7acc ("gpiolib: consolidate GPIO lookups")
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
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With SRCU we can now correctly handle the situation when a GPIO provider
is removed while having users still holding references to GPIO
descriptors. Remove all warnings emitted in this situation.
Suggested-by: Kent Gibson <warthog618@gmail.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Herve Codina <herve.codina@bootlin.com>
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Similar to gpiochip_generic_request() and gpiochip_generic_free() the
gpiochip_generic_config() function needs to handle the case where there
are no pinctrl pins mapped to the GPIOs, usually through the gpio-ranges
device tree property.
Commit f34fd6ee1be8 ("gpio: dwapb: Use generic request, free and
set_config") set the .set_config callback to gpiochip_generic_config()
in the dwapb GPIO driver so the GPIO API can set pinctrl configuration
for the corresponding pins. Most boards using the dwapb driver do not
set the gpio-ranges device tree property though, and in this case
gpiochip_generic_config() would return -EPROPE_DEFER rather than the
previous -ENOTSUPP return value. This in turn makes
gpio_set_config_with_argument_optional() fail and propagate the error to
any driver requesting GPIOs.
Fixes: 2956b5d94a76 ("pinctrl / gpio: Introduce .set_config() callback for GPIO chips")
Reported-by: Jisheng Zhang <jszhang@kernel.org>
Closes: https://lore.kernel.org/linux-gpio/ZdC_g3U4l0CJIWzh@xhacker/
Tested-by: Jisheng Zhang <jszhang@kernel.org>
Signed-off-by: Emil Renner Berthing <emil.renner.berthing@canonical.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
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Since commit 1f2bcb8c8ccd ("gpio: protect the descriptor label with
SRCU"), desc_set_label() already allocates memory for the label, so there
is no need to allocate it again. If we do, we leak it.
unreferenced object 0xffff0000c3e4d0c0 (size 32):
comm "kworker/u16:4", pid 60, jiffies 4294894555
hex dump (first 32 bytes):
72 65 67 75 6c 61 74 6f 72 2d 63 61 6e 32 2d 73 regulator-can2-s
74 62 79 00 00 00 ff ff ff ff ff ff eb db ff ff tby.............
backtrace (crc 2c3a0350):
[<00000000e93c5cf4>] kmemleak_alloc+0x34/0x40
[<0000000097a2657f>] __kmalloc_node_track_caller+0x2c4/0x524
[<000000000dd1c057>] kstrdup+0x4c/0x98
[<00000000b513a96a>] kstrdup_const+0x34/0x40
[<000000008a7f0feb>] gpiod_request_commit+0xdc/0x358
[<00000000fc71ad64>] gpiod_request+0xd8/0x204
[<00000000fa24b091>] gpiod_find_and_request+0x170/0x780
[<0000000086ecf92d>] gpiod_get_index+0x70/0xe0
[<000000004aef97f9>] gpiod_get_optional+0x18/0x30
[<00000000312f1b25>] reg_fixed_voltage_probe+0x58c/0xad8
[<00000000e6f47635>] platform_probe+0xc4/0x198
[<00000000cf78fbdb>] really_probe+0x204/0x5a8
[<00000000e28d05ec>] __driver_probe_device+0x158/0x2c4
[<00000000e4fe452b>] driver_probe_device+0x60/0x18c
[<00000000479fcf5d>] __device_attach_driver+0x168/0x208
[<000000007d389f38>] bus_for_each_drv+0x104/0x190
Fixes: 1f2bcb8c8ccd ("gpio: protect the descriptor label with SRCU")
Signed-off-by: Xiaolei Wang <xiaolei.wang@windriver.com>
[Bartosz: tweaked the commit message]
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
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The opaque pointer "data" in each match function used by
gpio_device_find() is a pointer to const, thus the same argument passed
to gpio_device_find() can adjusted similarly.
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
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There are two legacy, deprecated functions - gpiod_to_chip() and
gpio_device_get_chip() - that still have users in tree. They return the
address of the SRCU-protected chip outside of the read-only critical
sections. They are inherently dangerous and the users should convert to
safer alternatives. Let's explicitly silence lockdep warnings by using
rcu_dereference_check(ptr, 1). While at it: reuse
gpio_device_get_chip() in gpiod_to_chip().
Fixes: d83cee3d2bb1 ("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>
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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: d83cee3d2bb1 ("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>
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gpiod_hog() may be called without the gpio_device SRCU read lock taken
so we need to do it here as well. It's alright if someone else is
already holding the lock as SRCU read critical sections can be nested.
Fixes: d83cee3d2bb1 ("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>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
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In certain situations we may end up taking the GPIO descriptor SRCU read
lock in of_gpiochip_add() before the SRCU struct is initialized. Move
the initialization before the call to of_gpiochip_add().
Fixes: be711caa87c5 ("gpio: add SRCU infrastructure to struct gpio_desc")
Fixes: 1f2bcb8c8ccd ("gpio: protect the descriptor label with SRCU")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202402122228.e607a080-lkp@intel.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
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We still have some functions that return the address of the GPIO chip
associated with the GPIO device. This is dangerous and the users should
find a better solution. Let's add appropriate comments to the kernel
docs.
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>
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With all accesses to gdev->chip being protected with SRCU, we can now
remove the RW-semaphore specific to the character device which
fulfilled the same role up to this point.
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>
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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>
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Add the SRCU struct to GPIO device. It will be used to serialize access
to the GPIO chip pointer. Initialize and clean it up where applicable.
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>
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Duplicating the can_sleep value in GPIO device will allow us to not
needlessly dereference the chip pointer in several places and reduce the
number of SRCU read-only critical sections.
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>
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We don't need to check the gdev pointer in struct gpio_desc - it's
always assigned and never cleared. It's also pointless to check
gdev->chip before we actually serialize access to it.
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>
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Checking desc->gdev->chip for NULL without holding it in place with some
serializing mechanism is pointless. Remove this check. Also don't check
desc->gdev for NULL as it can never happen. We'll be protecting
gdev->chip with SRCU soon but we will provide a dedicated, automatic
class for that.
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>
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We don't need to dereference gdev->chip in gpiochip_setup_dev() as at
the time it's called, the label in the associated struct gpio_device is
already set.
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>
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The GPIO chip pointer is unused. Let's remove it.
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>
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We now removed the gpio_lock spinlock and modified the places
previously protected by it to handle desc->flags access in a consistent
way. Let's improve other places that were previously unprotected by
reading the flags field of gpio_desc once and using the stored value for
logic consistency. If we need to modify the field, let's also write it
back once with a consistent value resulting from the function's logic.
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>
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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>
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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>
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In order to ensure that the label is not freed while it's being
accessed, let's protect it with SRCU and synchronize it everytime it's
changed.
Let's modify desc_set_label() to manage the memory used for the label as
it can only be freed once synchronize_srcu() returns.
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>
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Extend the GPIO descriptor with an SRCU structure in order to serialize
the access to the label. Initialize and clean it up where applicable.
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>
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