On 8/6/21 8:57 AM, Damien Le Moal wrote: > On 2021/08/06 15:35, Hannes Reinecke wrote: >> On 8/6/21 7:11 AM, Damien Le Moal wrote: >>> An iocb aio_reqprio field 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. >>> >>> While at it, cleanup the following: >>> * Apply the mask IOPRIO_PRIO_MASK to the data argument of the >>> IOPRIO_PRIO_VALUE() macro to ignore upper bits of the data value. >>> * Remove unnecessary parenthesis around fixed values in the macro >>> definitions in include/uapi/linux/ioprio.h. >>> * Update the outdated mention of CFQ in the comment describing priority >>> classes and instead mention BFQ and mq-deadline. >>> * Change the argument name of the IOPRIO_PRIO_CLASS() and >>> IOPRIO_PRIO_DATA() macros from "mask" to "ioprio" to reflect the fact >>> that an IO priority value should be passed rather than a mask. >>> * Change the ioprio_valid() macro into an inline function, adding a >>> check on the maximum value of the class of a priority value as >>> defined by the IOPRIO_CLASS_MAX enum value. Move this function to >>> the kernel side in include/linux/ioprio.h. >>> * Remove the unnecessary "else" after the return statements in >>> task_nice_ioclass(). >>> >>> Signed-off-by: Damien Le Moal <damien.lemoal@xxxxxxx> >>> --- >>> include/linux/ioprio.h | 15 ++++++++++++--- >>> include/uapi/linux/ioprio.h | 19 +++++++++++-------- >>> 2 files changed, 23 insertions(+), 11 deletions(-) >>> >>> diff --git a/include/linux/ioprio.h b/include/linux/ioprio.h >>> index ef9ad4fb245f..9b3a6d8172b4 100644 >>> --- a/include/linux/ioprio.h >>> +++ b/include/linux/ioprio.h >>> @@ -8,6 +8,16 @@ >>> >>> #include <uapi/linux/ioprio.h> >>> >>> +/* >>> + * Check that a priority value has a valid class. >>> + */ >>> +static inline bool ioprio_valid(unsigned short ioprio) >> >> Wouldn't it be better to use 'u16' here as type, as we're relying on the >> number of bits? > > Other functions in block/ioprio.c and in include/linux/ioprio.h use "unsigned > short", so I followed. But many functions, if not most, use "int". This is all a > bit of a mess. I think we need a "typedef ioprio_t u16;" to clean things up. But > there are a lot of places to fix. I can add such patch... Worth it ? > Possibly not. Consider my comment retracted :-) Cheers, Hannes -- Dr. Hannes Reinecke Kernel Storage Architect hare@xxxxxxx +49 911 74053 688 SUSE Software Solutions Germany GmbH, Maxfeldstr. 5, 90409 Nürnberg HRB 36809 (AG Nürnberg), GF: Felix Imendörffer
