| Message ID | 1722409287-12183-1-git-send-email-zhiguo.niu@unisoc.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [V3] block: uapi: Use unsigned int type for IOPRIO_PRIO_MASK | expand |
On 7/31/24 16:01, Zhiguo Niu wrote: > Generally, the input of IOPRIO_PRIO_DATA has 16 bits, but the output of > IOPRIO_PRIO_DATA will be expanded to "UL" from IOPRIO_PRIO_MASK. > #define IOPRIO_PRIO_MASK ((1UL << IOPRIO_CLASS_SHIFT) - 1) > This is not reasonable and meaningless, unsigned int is more suitable for it. > > So if use format "%d" to print IOPRIO_PRIO_DATA directly, there will be a > build warning or error showned as the following, which is from the > local test when I modify f2fs codes. > > fs/f2fs/sysfs.c:348:31: warning: format ‘%d’ expects argument of type ‘int’, > but argument 4 has type ‘long unsigned int’ [-Wformat=] > return sysfs_emit(buf, "%s,%d\n", > ~^ > %ld > > When modules use IOPRIO_PRIO_CLASS & IOPRIO_PRIO_LEVEL get ioprio's class and > level, their outputs are both unsigned int. > IOPRIO_CLASS_MASK is: > #define IOPRIO_CLASS_SHIFT 13 > #define IOPRIO_NR_CLASSES 8 > #define IOPRIO_CLASS_MASK (IOPRIO_NR_CLASSES - 1) > IOPRIO_LEVEL_MASK is: > #define IOPRIO_LEVEL_NR_BITS 3 > #define IOPRIO_NR_LEVELS (1 << IOPRIO_LEVEL_NR_BITS) > #define IOPRIO_LEVEL_MASK (IOPRIO_NR_LEVELS - 1) > > Ioprio is passed along as an int internally, so we should not be using an > unsigned long for IOPRIO_PRIO_MASK to not end up with IOPRIO_PRIO_DATA > returning an unsigned long as well. I would write this commit message like this: An ioprio is passed internally as an int value. When IOPRIO_PRIO_CLASS() and IOPRIO_PRIO_LEVEL() are used to extract from it the priority class and level, the values obtained are thus also int. However, the IOPRIO_PRIO_MASK() macro used to define the IOPRIO_PRIO_DATA() macro is defined as: #define IOPRIO_PRIO_MASK ((1UL << IOPRIO_CLASS_SHIFT) - 1) that is, the macro gives an unsigned long value, which leads to IOPRIO_PRIO_DATA() also returning an unsigned long. Make things consistent between class, level and data and use int everywhere by removing forced unsigned long from IOPRIO_PRIO_MASK.
Hi Damien Le Moal Damien Le Moal <dlemoal@kernel.org> 于2024年7月31日周三 17:28写道： > > On 7/31/24 16:01, Zhiguo Niu wrote: > > Generally, the input of IOPRIO_PRIO_DATA has 16 bits, but the output of > > IOPRIO_PRIO_DATA will be expanded to "UL" from IOPRIO_PRIO_MASK. > > #define IOPRIO_PRIO_MASK ((1UL << IOPRIO_CLASS_SHIFT) - 1) > > This is not reasonable and meaningless, unsigned int is more suitable for it. > > > > So if use format "%d" to print IOPRIO_PRIO_DATA directly, theire will be a > > build warning or error showned as the following, which is from the > > local test when I modify f2fs codes. > > > > fs/f2fs/sysfs.c:348:31: warning: format ‘%d’ expects argument of type ‘int’, > > but argument 4 has type ‘long unsigned int’ [-Wformat=] > > return sysfs_emit(buf, "%s,%d\n", > > ~^ > > %ld > > > > When modules use IOPRIO_PRIO_CLASS & IOPRIO_PRIO_LEVEL get ioprio's class and > > level, their outputs are both unsigned int. > > IOPRIO_CLASS_MASK is: > > #define IOPRIO_CLASS_SHIFT 13 > > #define IOPRIO_NR_CLASSES 8 > > #define IOPRIO_CLASS_MASK (IOPRIO_NR_CLASSES - 1) > > IOPRIO_LEVEL_MASK is: > > #define IOPRIO_LEVEL_NR_BITS 3 > > #define IOPRIO_NR_LEVELS (1 << IOPRIO_LEVEL_NR_BITS) > > #define IOPRIO_LEVEL_MASK (IOPRIO_NR_LEVELS - 1) > > > > Ioprio is passed along as an int internally, so we should not be using an > > unsigned long for IOPRIO_PRIO_MASK to not end up with IOPRIO_PRIO_DATA > > returning an unsigned long as well. > > I would write this commit message like this: > > > An ioprio is passed internally as an int value. When IOPRIO_PRIO_CLASS() and > IOPRIO_PRIO_LEVEL() are used to extract from it the priority class and level, > the values obtained are thus also int. > However, the IOPRIO_PRIO_MASK() macro used to define the IOPRIO_PRIO_DATA() > macro is defined as: > > #define IOPRIO_PRIO_MASK ((1UL << IOPRIO_CLASS_SHIFT) - 1) > > that is, the macro gives an unsigned long value, which leads to > IOPRIO_PRIO_DATA() also returning an unsigned long. > > Make things consistent between class, level and data and use int everywhere by > removing forced unsigned long from IOPRIO_PRIO_MASK. Thank you for your professional advice and sharing. I will update this. > > > > -- > Damien Le Moal > Western Digital Research >
diff --git a/include/uapi/linux/ioprio.h b/include/uapi/linux/ioprio.h index bee2bdb0..9ead07f 100644 --- a/include/uapi/linux/ioprio.h +++ b/include/uapi/linux/ioprio.h @@ -11,7 +11,7 @@ #define IOPRIO_CLASS_SHIFT 13 #define IOPRIO_NR_CLASSES 8 #define IOPRIO_CLASS_MASK (IOPRIO_NR_CLASSES - 1) -#define IOPRIO_PRIO_MASK ((1UL << IOPRIO_CLASS_SHIFT) - 1) +#define IOPRIO_PRIO_MASK ((1U << IOPRIO_CLASS_SHIFT) - 1) #define IOPRIO_PRIO_CLASS(ioprio) \ (((ioprio) >> IOPRIO_CLASS_SHIFT) & IOPRIO_CLASS_MASK)
Generally, the input of IOPRIO_PRIO_DATA has 16 bits, but the output of IOPRIO_PRIO_DATA will be expanded to "UL" from IOPRIO_PRIO_MASK. #define IOPRIO_PRIO_MASK ((1UL << IOPRIO_CLASS_SHIFT) - 1) This is not reasonable and meaningless, unsigned int is more suitable for it. So if use format "%d" to print IOPRIO_PRIO_DATA directly, there will be a build warning or error showned as the following, which is from the local test when I modify f2fs codes. fs/f2fs/sysfs.c:348:31: warning: format ‘%d’ expects argument of type ‘int’, but argument 4 has type ‘long unsigned int’ [-Wformat=] return sysfs_emit(buf, "%s,%d\n", ~^ %ld When modules use IOPRIO_PRIO_CLASS & IOPRIO_PRIO_LEVEL get ioprio's class and level, their outputs are both unsigned int. IOPRIO_CLASS_MASK is: #define IOPRIO_CLASS_SHIFT 13 #define IOPRIO_NR_CLASSES 8 #define IOPRIO_CLASS_MASK (IOPRIO_NR_CLASSES - 1) IOPRIO_LEVEL_MASK is: #define IOPRIO_LEVEL_NR_BITS 3 #define IOPRIO_NR_LEVELS (1 << IOPRIO_LEVEL_NR_BITS) #define IOPRIO_LEVEL_MASK (IOPRIO_NR_LEVELS - 1) Ioprio is passed along as an int internally, so we should not be using an unsigned long for IOPRIO_PRIO_MASK to not end up with IOPRIO_PRIO_DATA returning an unsigned long as well. Fixes: 06447ae5e33b ("ioprio: move user space relevant ioprio bits to UAPI includes") Cc: stable@vger.kernel.org Cc: Oliver Hartkopp <socketcan@hartkopp.net> Signed-off-by: Zhiguo Niu <zhiguo.niu@unisoc.com> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Link: https://lore.kernel.org/all/1717155071-20409-1-git-send-email-zhiguo.niu@unisoc.com --- v3: modify commit message according to Damien Le Moal'ssuggestion v2: add Fixes tag and Cc tag --- --- include/uapi/linux/ioprio.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)