Linux-GPIO Archive on
 help / color / Atom feed
* [PATCH] gpiolib: hold gpio devices lock until ->descs array is initialised
@ 2019-12-02  4:59 Dan Callaghan
  0 siblings, 0 replies; only message in thread
From: Dan Callaghan @ 2019-12-02  4:59 UTC (permalink / raw)
  To: linux-gpio; +Cc: Dan Callaghan

If a driver consuming the GPIO chip is being probed at the same time as
the GPIO driver is registering the chip, it is possible for the
consuming driver to see the ->descs array in an uninitialised state.
For example, the gpio-keys-polled driver can fail like this:

    kernel: gpiod_request: invalid GPIO (no device)
    kernel: gpio-keys-polled PRP0001:07: failed to get gpio: -22
    kernel: gpio-keys-polled: probe of PRP0001:07 failed with error -22

This patch makes gpiochip_add() hold the lock protecting gpio_devices
until it has finished setting desc->gdev on the newly inserted list

Signed-off-by: Dan Callaghan <>
 drivers/gpio/gpiolib.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index dce0b31f4125..93eec6dbd9c7 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1487,11 +1487,11 @@ int gpiochip_add_data_with_key(struct gpio_chip *chip, void *data,
 		goto err_free_label;
-	spin_unlock_irqrestore(&gpio_lock, flags);
 	for (i = 0; i < chip->ngpio; i++)
 		gdev->descs[i].gdev = gdev;
+	spin_unlock_irqrestore(&gpio_lock, flags);

^ permalink raw reply	[flat|nested] only message in thread

only message in thread, back to index

Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-12-02  4:59 [PATCH] gpiolib: hold gpio devices lock until ->descs array is initialised Dan Callaghan

Linux-GPIO Archive on

Archives are clonable:
	git clone --mirror linux-gpio/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-gpio linux-gpio/ \
	public-inbox-index linux-gpio

Example config snippet for mirrors

Newsgroup available over NNTP:

AGPL code for this site: git clone