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@xxxxxxx> --- include/uapi/linux/ioprio.h | 12 ++++++++---- 1 file 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 -- 2.31.1
