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| author |   David Brownell <dbrownell@users.sourceforge.net> | 2008-10-18 20:27:49 -0700 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2008-10-20 08:52:36 -0700 |
| commit | 978ccaa8ea5d8c7bf6b676209f2fc126eae6355b (patch) | |
| tree | 4d639469edbdb2df8ec364bae1719bd083bc04da /drivers/gpio | |
| parent | gpio: modify sysfs gpio export so that "value" displays as 0 or 1 (diff) | |
| download | linux-dev-978ccaa8ea5d8c7bf6b676209f2fc126eae6355b.tar.xz linux-dev-978ccaa8ea5d8c7bf6b676209f2fc126eae6355b.zip | |
gpiolib: fix oops in gpio_get_value_cansleep()
We can get the following oops from gpio_get_value_cansleep() when a GPIO
controller doesn't provide a get() callback:
Unable to handle kernel paging request for instruction fetch
Faulting instruction address: 0x00000000
Oops: Kernel access of bad area, sig: 11 [#1]
[...]
NIP [00000000] 0x0
LR [c0182fb0] gpio_get_value_cansleep+0x40/0x50
Call Trace:
[c7b79e80] [c0183f28] gpio_value_show+0x5c/0x94
[c7b79ea0] [c01a584c] dev_attr_show+0x30/0x7c
[c7b79eb0] [c00d6b48] fill_read_buffer+0x68/0xe0
[c7b79ed0] [c00d6c54] sysfs_read_file+0x94/0xbc
[c7b79ef0] [c008f24c] vfs_read+0xb4/0x16c
[c7b79f10] [c008f580] sys_read+0x4c/0x90
[c7b79f40] [c0013a14] ret_from_syscall+0x0/0x38
It's OK to request the value of *any* GPIO; most GPIOs are bidirectional,
so configuring them as outputs just enables an output driver and doesn't
disable the input logic.
So the problem is that gpio_get_value_cansleep() isn't making the same
sanity check that gpio_get_value() does: making sure this GPIO isn't one
of the atypical "no input logic" cases.
Reported-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: <stable@kernel.org> [2.6.27.x, 2.6.26.x, 2.6.25.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/gpio')
| -rw-r--r-- | drivers/gpio/gpiolib.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 70de72c443e4..22edc4273ef6 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -1105,7 +1105,7 @@ int gpio_get_value_cansleep(unsigned gpio) might_sleep_if(extra_checks); chip = gpio_to_chip(gpio); - return chip->get(chip, gpio - chip->base); + return chip->get ? chip->get(chip, gpio - chip->base) : 0; } EXPORT_SYMBOL_GPL(gpio_get_value_cansleep); |