diff options
| author | Damien Le Moal | 2021-08-11 12:37:00 +0900 |
|---|---|---|
| committer | Jens Axboe | 2021-08-18 07:21:12 -0600 |
| commit | ba05200fcce0a73fa8db16c514fbaa476d1d9399 (patch) | |
| tree | b8d4a85dcb8c38149b887d60d12279ac8c135b57 /include/uapi | |
| parent | a553a835ca57668b0d9907d8ec2507ec51292d9a (diff) | |
block: fix IOPRIO_PRIO_CLASS() and IOPRIO_PRIO_VALUE() macros
The ki_ioprio field of struct kiocb is 16-bits (u16) but often handled
as an int in the block layer. E.g. ioprio_check_cap() takes an int as
argument.
With such implicit int casting function calls, the upper 16-bits of the
int argument may be left uninitialized by the compiler, resulting in
invalid values for the IOPRIO_PRIO_CLASS() macro (garbage upper bits)
and in an error return for functions such as ioprio_check_cap().
Fix this by masking the result of the shift by IOPRIO_CLASS_SHIFT bits
in the IOPRIO_PRIO_CLASS() macro. The new macro IOPRIO_CLASS_MASK
defines the 3-bits mask for the priority class.
Similarly, apply the IOPRIO_PRIO_MASK mask to the data argument of the
IOPRIO_PRIO_VALUE() macro to ignore the upper bits of the data value.
The IOPRIO_CLASS_MASK mask is also applied to the class argument of this
macro before shifting the result by IOPRIO_CLASS_SHIFT bits.
While at it, also change the argument name of the IOPRIO_PRIO_CLASS()
and IOPRIO_PRIO_DATA() macros from "mask" to "ioprio" to reflect the
fact that a priority value should be passed rather than a mask.
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Link: https://lore.kernel.org/r/20210811033702.368488-5-damien.lemoal@wdc.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'include/uapi')
| -rw-r--r-- | include/uapi/linux/ioprio.h | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/include/uapi/linux/ioprio.h b/include/uapi/linux/ioprio.h index 5064e230374c..936f0d8f30e1 100644 --- a/include/uapi/linux/ioprio.h +++ b/include/uapi/linux/ioprio.h @@ -5,12 +5,16 @@ /* * Gives us 8 prio classes with 13-bits of data for each class */ -#define IOPRIO_CLASS_SHIFT (13) +#define IOPRIO_CLASS_SHIFT 13 +#define IOPRIO_CLASS_MASK 0x07 #define IOPRIO_PRIO_MASK ((1UL << IOPRIO_CLASS_SHIFT) - 1) -#define IOPRIO_PRIO_CLASS(mask) ((mask) >> IOPRIO_CLASS_SHIFT) -#define IOPRIO_PRIO_DATA(mask) ((mask) & IOPRIO_PRIO_MASK) -#define IOPRIO_PRIO_VALUE(class, data) (((class) << IOPRIO_CLASS_SHIFT) | data) +#define IOPRIO_PRIO_CLASS(ioprio) \ + (((ioprio) >> IOPRIO_CLASS_SHIFT) & IOPRIO_CLASS_MASK) +#define IOPRIO_PRIO_DATA(ioprio) ((ioprio) & IOPRIO_PRIO_MASK) +#define IOPRIO_PRIO_VALUE(class, data) \ + ((((class) & IOPRIO_CLASS_MASK) << IOPRIO_CLASS_SHIFT) | \ + ((data) & IOPRIO_PRIO_MASK)) /* * These are the io priority groups as implemented by the BFQ and mq-deadline |