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ba05200fcc
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>
51 lines
1.3 KiB
C
51 lines
1.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
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#ifndef _UAPI_LINUX_IOPRIO_H
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#define _UAPI_LINUX_IOPRIO_H
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/*
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* Gives us 8 prio classes with 13-bits of data for each class
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*/
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#define IOPRIO_CLASS_SHIFT 13
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#define IOPRIO_CLASS_MASK 0x07
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#define IOPRIO_PRIO_MASK ((1UL << IOPRIO_CLASS_SHIFT) - 1)
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#define IOPRIO_PRIO_CLASS(ioprio) \
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(((ioprio) >> IOPRIO_CLASS_SHIFT) & IOPRIO_CLASS_MASK)
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#define IOPRIO_PRIO_DATA(ioprio) ((ioprio) & IOPRIO_PRIO_MASK)
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#define IOPRIO_PRIO_VALUE(class, data) \
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((((class) & IOPRIO_CLASS_MASK) << IOPRIO_CLASS_SHIFT) | \
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((data) & IOPRIO_PRIO_MASK))
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/*
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* These are the io priority groups as implemented by the BFQ and mq-deadline
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* schedulers. RT is the realtime class, it always gets premium service. For
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* ATA disks supporting NCQ IO priority, RT class IOs will be processed using
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* high priority NCQ commands. BE is the best-effort scheduling class, the
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* default for any process. IDLE is the idle scheduling class, it is only
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* served when no one else is using the disk.
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*/
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enum {
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IOPRIO_CLASS_NONE,
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IOPRIO_CLASS_RT,
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IOPRIO_CLASS_BE,
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IOPRIO_CLASS_IDLE,
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};
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/*
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* 8 best effort priority levels are supported
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*/
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#define IOPRIO_BE_NR (8)
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enum {
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IOPRIO_WHO_PROCESS = 1,
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IOPRIO_WHO_PGRP,
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IOPRIO_WHO_USER,
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};
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/*
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* Fallback BE priority
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*/
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#define IOPRIO_NORM (4)
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#endif /* _UAPI_LINUX_IOPRIO_H */
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