linux-stable.git/drivers/gpio, branch v6.14

gpio: cdev: use raw notifier for line state events

2025-03-13T08:20:12+00:00

We use a notifier to implement the mechanism of informing the user-space
about changes in GPIO line status. We register with the notifier when
the GPIO character device file is opened and unregister when the last
reference to the associated file descriptor is dropped.

Since commit fcc8b637c542 ("gpiolib: switch the line state notifier to
atomic") we use the atomic notifier variant. Atomic notifiers call
rcu_synchronize in atomic_notifier_chain_unregister() which caused a
significant performance regression in some circumstances, observed by
user-space when calling close() on the GPIO device file descriptor.

Replace the atomic notifier with the raw variant and provide
synchronization with a read-write spinlock.

Fixes: fcc8b637c542 ("gpiolib: switch the line state notifier to atomic")
Reported-by: David Jander 
Closes: https://lore.kernel.org/all/20250311110034.53959031@erd003.prtnl/
Tested-by: David Jander 
Tested-by: Kent Gibson 
Link: https://lore.kernel.org/r/20250311-gpiolib-line-state-raw-notifier-v2-1-138374581e1e@linaro.org
Signed-off-by: Bartosz Golaszewski

gpiolib: don't check the retval of get_direction() when registering a chip

2025-03-13T08:19:34+00:00

During chip registration we should neither check the return value of
gc->get_direction() nor hold the SRCU lock when calling it. The former
is because pin controllers may have pins set to alternate functions and
return errors from their get_direction() callbacks. That's alright - we
should default to the safe INPUT state and not bail-out. The latter is
not needed because we haven't registered the chip yet so there's nothing
to protect against dynamic removal. In fact: we currently hit a lockdep
splat. Revert to calling the gc->get_direction() callback directly and
*not* checking its value.

Fixes: 9d846b1aebbe ("gpiolib: check the return value of gpio_chip::get_direction()")
Reported-by: Marek Szyprowski 
Closes: https://lore.kernel.org/all/81f890fc-6688-42f0-9756-567efc8bb97a@samsung.com/
Reviewed-by: Andy Shevchenko 
Tested-by: Marek Szyprowski 
Link: https://lore.kernel.org/r/20250226-retval-fixes-v2-1-c8dc57182441@linaro.org
Tested-by: Gene C 
Link: https://lore.kernel.org/r/20250311175631.83779-1-brgl@bgdev.pl
Signed-off-by: Bartosz Golaszewski

gpio: rcar: Fix missing of_node_put() call

2025-03-06T14:51:27+00:00

of_parse_phandle_with_fixed_args() requires its caller to
call into of_node_put() on the node pointer from the output
structure, but such a call is currently missing.

Call into of_node_put() to rectify that.

Fixes: 159f8a0209af ("gpio-rcar: Add DT support")
Signed-off-by: Fabrizio Castro 
Reviewed-by: Lad Prabhakar 
Reviewed-by: Geert Uytterhoeven 
Link: https://lore.kernel.org/r/20250305163753.34913-2-fabrizio.castro.jz@renesas.com
Signed-off-by: Bartosz Golaszewski

gpio: rcar: Use raw_spinlock to protect register access

2025-03-05T12:14:27+00:00

Use raw_spinlock in order to fix spurious messages about invalid context
when spinlock debugging is enabled. The lock is only used to serialize
register access.

    [    4.239592] =============================
    [    4.239595] [ BUG: Invalid wait context ]
    [    4.239599] 6.13.0-rc7-arm64-renesas-05496-gd088502a519f #35 Not tainted
    [    4.239603] -----------------------------
    [    4.239606] kworker/u8:5/76 is trying to lock:
    [    4.239609] ffff0000091898a0 (&p->lock){....}-{3:3}, at: gpio_rcar_config_interrupt_input_mode+0x34/0x164
    [    4.239641] other info that might help us debug this:
    [    4.239643] context-{5:5}
    [    4.239646] 5 locks held by kworker/u8:5/76:
    [    4.239651]  #0: ffff0000080fb148 ((wq_completion)async){+.+.}-{0:0}, at: process_one_work+0x190/0x62c
    [    4.250180] OF: /soc/sound@ec500000/ports/port@0/endpoint: Read of boolean property 'frame-master' with a value.
    [    4.254094]  #1: ffff80008299bd80 ((work_completion)(&entry->work)){+.+.}-{0:0}, at: process_one_work+0x1b8/0x62c
    [    4.254109]  #2: ffff00000920c8f8
    [    4.258345] OF: /soc/sound@ec500000/ports/port@1/endpoint: Read of boolean property 'bitclock-master' with a value.
    [    4.264803]  (&dev->mutex){....}-{4:4}, at: __device_attach_async_helper+0x3c/0xdc
    [    4.264820]  #3: ffff00000a50ca40 (request_class#2){+.+.}-{4:4}, at: __setup_irq+0xa0/0x690
    [    4.264840]  #4:
    [    4.268872] OF: /soc/sound@ec500000/ports/port@1/endpoint: Read of boolean property 'frame-master' with a value.
    [    4.273275] ffff00000a50c8c8 (lock_class){....}-{2:2}, at: __setup_irq+0xc4/0x690
    [    4.296130] renesas_sdhi_internal_dmac ee100000.mmc: mmc1 base at 0x00000000ee100000, max clock rate 200 MHz
    [    4.304082] stack backtrace:
    [    4.304086] CPU: 1 UID: 0 PID: 76 Comm: kworker/u8:5 Not tainted 6.13.0-rc7-arm64-renesas-05496-gd088502a519f #35
    [    4.304092] Hardware name: Renesas Salvator-X 2nd version board based on r8a77965 (DT)
    [    4.304097] Workqueue: async async_run_entry_fn
    [    4.304106] Call trace:
    [    4.304110]  show_stack+0x14/0x20 (C)
    [    4.304122]  dump_stack_lvl+0x6c/0x90
    [    4.304131]  dump_stack+0x14/0x1c
    [    4.304138]  __lock_acquire+0xdfc/0x1584
    [    4.426274]  lock_acquire+0x1c4/0x33c
    [    4.429942]  _raw_spin_lock_irqsave+0x5c/0x80
    [    4.434307]  gpio_rcar_config_interrupt_input_mode+0x34/0x164
    [    4.440061]  gpio_rcar_irq_set_type+0xd4/0xd8
    [    4.444422]  __irq_set_trigger+0x5c/0x178
    [    4.448435]  __setup_irq+0x2e4/0x690
    [    4.452012]  request_threaded_irq+0xc4/0x190
    [    4.456285]  devm_request_threaded_irq+0x7c/0xf4
    [    4.459398] ata1: link resume succeeded after 1 retries
    [    4.460902]  mmc_gpiod_request_cd_irq+0x68/0xe0
    [    4.470660]  mmc_start_host+0x50/0xac
    [    4.474327]  mmc_add_host+0x80/0xe4
    [    4.477817]  tmio_mmc_host_probe+0x2b0/0x440
    [    4.482094]  renesas_sdhi_probe+0x488/0x6f4
    [    4.486281]  renesas_sdhi_internal_dmac_probe+0x60/0x78
    [    4.491509]  platform_probe+0x64/0xd8
    [    4.495178]  really_probe+0xb8/0x2a8
    [    4.498756]  __driver_probe_device+0x74/0x118
    [    4.503116]  driver_probe_device+0x3c/0x154
    [    4.507303]  __device_attach_driver+0xd4/0x160
    [    4.511750]  bus_for_each_drv+0x84/0xe0
    [    4.515588]  __device_attach_async_helper+0xb0/0xdc
    [    4.520470]  async_run_entry_fn+0x30/0xd8
    [    4.524481]  process_one_work+0x210/0x62c
    [    4.528494]  worker_thread+0x1ac/0x340
    [    4.532245]  kthread+0x10c/0x110
    [    4.535476]  ret_from_fork+0x10/0x20

Signed-off-by: Niklas Söderlund 
Reviewed-by: Geert Uytterhoeven 
Tested-by: Geert Uytterhoeven 
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20250121135833.3769310-1-niklas.soderlund+renesas@ragnatech.se
Signed-off-by: Bartosz Golaszewski

gpio: aggregator: protect driver attr handlers against module unload

2025-03-05T12:14:19+00:00

Both new_device_store and delete_device_store touch module global
resources (e.g. gpio_aggregator_lock). To prevent race conditions with
module unload, a reference needs to be held.

Add try_module_get() in these handlers.

For new_device_store, this eliminates what appears to be the most dangerous
scenario: if an id is allocated from gpio_aggregator_idr but
platform_device_register has not yet been called or completed, a concurrent
module unload could fail to unregister/delete the device, leaving behind a
dangling platform device/GPIO forwarder. This can result in various issues.
The following simple reproducer demonstrates these problems:

  #!/bin/bash
  while :; do
    # note: whether 'gpiochip0 0' exists or not does not matter.
    echo 'gpiochip0 0' > /sys/bus/platform/drivers/gpio-aggregator/new_device
  done &
  while :; do
    modprobe gpio-aggregator
    modprobe -r gpio-aggregator
  done &
  wait

  Starting with the following warning, several kinds of warnings will appear
  and the system may become unstable:

  ------------[ cut here ]------------
  list_del corruption, ffff888103e2e980->next is LIST_POISON1 (dead000000000100)
  WARNING: CPU: 1 PID: 1327 at lib/list_debug.c:56 __list_del_entry_valid_or_report+0xa3/0x120
  [...]
  RIP: 0010:__list_del_entry_valid_or_report+0xa3/0x120
  [...]
  Call Trace:
   
   ? __list_del_entry_valid_or_report+0xa3/0x120
   ? __warn.cold+0x93/0xf2
   ? __list_del_entry_valid_or_report+0xa3/0x120
   ? report_bug+0xe6/0x170
   ? __irq_work_queue_local+0x39/0xe0
   ? handle_bug+0x58/0x90
   ? exc_invalid_op+0x13/0x60
   ? asm_exc_invalid_op+0x16/0x20
   ? __list_del_entry_valid_or_report+0xa3/0x120
   gpiod_remove_lookup_table+0x22/0x60
   new_device_store+0x315/0x350 [gpio_aggregator]
   kernfs_fop_write_iter+0x137/0x1f0
   vfs_write+0x262/0x430
   ksys_write+0x60/0xd0
   do_syscall_64+0x6c/0x180
   entry_SYSCALL_64_after_hwframe+0x76/0x7e
   [...]
   
  ---[ end trace 0000000000000000 ]---

Fixes: 828546e24280 ("gpio: Add GPIO Aggregator")
Cc: stable@vger.kernel.org
Signed-off-by: Koichiro Den 
Link: https://lore.kernel.org/r/20250224143134.3024598-2-koichiro.den@canonical.com
Signed-off-by: Bartosz Golaszewski

gpiolib: Fix Oops in gpiod_direction_input_nonotify()

2025-02-28T15:30:48+00:00

The gpiod_direction_input_nonotify() function is supposed to return zero
if the direction for the pin is input.  But instead it accidentally
returns GPIO_LINE_DIRECTION_IN (1) which will be cast into an ERR_PTR()
in gpiochip_request_own_desc().  The callers dereference it and it leads
to a crash.

I changed gpiod_direction_output_raw_commit() just for consistency but
returning GPIO_LINE_DIRECTION_OUT (0) is fine.

Cc: stable@vger.kernel.org
Fixes: 9d846b1aebbe ("gpiolib: check the return value of gpio_chip::get_direction()")
Signed-off-by: Dan Carpenter 
Link: https://lore.kernel.org/r/254f3925-3015-4c9d-aac5-bb9b4b2cd2c5@stanley.mountain
[Bartosz: moved the variable declarations to the top of the functions]
Signed-off-by: Bartosz Golaszewski

gpiolib: don't bail out if get_direction() fails in gpiochip_add_data()

2025-02-20T13:08:18+00:00

Since commit 9d846b1aebbe ("gpiolib: check the return value of
gpio_chip::get_direction()") we check the return value of the
get_direction() callback as per its API contract. Some drivers have been
observed to fail to register now as they may call get_direction() in
gpiochip_add_data() in contexts where it has always silently failed.
Until we audit all drivers, replace the bail-out to a kernel log
warning.

Fixes: 9d846b1aebbe ("gpiolib: check the return value of gpio_chip::get_direction()")
Reported-by: Mark Brown 
Closes: https://lore.kernel.org/all/Z7VFB1nST6lbmBIo@finisterre.sirena.org.uk/
Reported-by: Marek Szyprowski 
Closes: https://lore.kernel.org/all/dfe03f88-407e-4ef1-ad30-42db53bbd4e4@samsung.com/
Tested-by: Mark Brown 
Reviewed-by: Mark Brown 
Tested-by: Marek Szyprowski 
Link: https://lore.kernel.org/r/20250219144356.258635-1-brgl@bgdev.pl
Signed-off-by: Bartosz Golaszewski

gpiolib: protect gpio_chip with SRCU in array_info paths in multi get/set

2025-02-18T10:23:34+00:00

During the locking rework in GPIOLIB, we omitted one important use-case,
namely: setting and getting values for GPIO descriptor arrays with
array_info present.

This patch does two things: first it makes struct gpio_array store the
address of the underlying GPIO device and not chip. Next: it protects
the chip with SRCU from removal in gpiod_get_array_value_complex() and
gpiod_set_array_value_complex().

Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20250215095655.23152-1-brgl@bgdev.pl
Signed-off-by: Bartosz Golaszewski

gpio: vf610: add locking to gpio direction functions

2025-02-17T10:57:54+00:00

Add locking to `vf610_gpio_direction_input|output()` functions. Without
this locking, a race condition exists between concurrent calls to these
functions, potentially leading to incorrect GPIO direction settings.

To verify the correctness of this fix, a `trylock` patch was applied,
where after a couple of reboots the race was confirmed. I.e., one user
had to wait before acquiring the lock. With this patch the race has not
been encountered. It's worth mentioning that any type of debugging
(printing, tracing, etc.) would "resolve"/hide the issue.

Fixes: 659d8a62311f ("gpio: vf610: add imx7ulp support")
Signed-off-by: Johan Korsnes 
Reviewed-by: Linus Walleij 
Reviewed-by: Haibo Chen 
Cc: Bartosz Golaszewski 
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20250217091643.679644-1-johan.korsnes@remarkable.no
Signed-off-by: Bartosz Golaszewski

gpiolib: check the return value of gpio_chip::get_direction()

2025-02-17T10:50:50+00:00

As per the API contract - gpio_chip::get_direction() may fail and return
a negative error number. However, we treat it as if it always returned 0
or 1. Check the return value of the callback and propagate the error
number up the stack.

Cc: stable@vger.kernel.org
Reviewed-by: Linus Walleij 
Link: https://lore.kernel.org/r/20250210-gpio-sanitize-retvals-v1-1-12ea88506cb2@linaro.org
Signed-off-by: Bartosz Golaszewski