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Nathan Chancellor 2870cd0286 blk-iocost: Avoid using clamp() on inuse in __propagate_weights()
[ Upstream commit 57e420c84f9ab55ba4c5e2ae9c5f6c8e1ea834d2 ]

After a recent change to clamp() and its variants [1] that increases the
coverage of the check that high is greater than low because it can be
done through inlining, certain build configurations (such as s390
defconfig) fail to build with clang with:

  block/blk-iocost.c:1101:11: error: call to '__compiletime_assert_557' declared with 'error' attribute: clamp() low limit 1 greater than high limit active
   1101 |                 inuse = clamp_t(u32, inuse, 1, active);
        |                         ^
  include/linux/minmax.h:218:36: note: expanded from macro 'clamp_t'
    218 | #define clamp_t(type, val, lo, hi) __careful_clamp(type, val, lo, hi)
        |                                    ^
  include/linux/minmax.h:195:2: note: expanded from macro '__careful_clamp'
    195 |         __clamp_once(type, val, lo, hi, __UNIQUE_ID(v_), __UNIQUE_ID(l_), __UNIQUE_ID(h_))
        |         ^
  include/linux/minmax.h:188:2: note: expanded from macro '__clamp_once'
    188 |         BUILD_BUG_ON_MSG(statically_true(ulo > uhi),                            \
        |         ^

__propagate_weights() is called with an active value of zero in
ioc_check_iocgs(), which results in the high value being less than the
low value, which is undefined because the value returned depends on the
order of the comparisons.

The purpose of this expression is to ensure inuse is not more than
active and at least 1. This could be written more simply with a ternary
expression that uses min(inuse, active) as the condition so that the
value of that condition can be used if it is not zero and one if it is.
Do this conversion to resolve the error and add a comment to deter
people from turning this back into clamp().

Fixes: 7caa47151a ("blkcg: implement blk-iocost")
Link: https://lore.kernel.org/r/34d53778977747f19cce2abb287bb3e6@AcuMS.aculab.com/ [1]
Suggested-by: David Laight <david.laight@aculab.com>
Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
Closes: https://lore.kernel.org/llvm/CA+G9fYsD7mw13wredcZn0L-KBA3yeoVSTuxnss-AEWMN3ha0cA@mail.gmail.com/
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202412120322.3GfVe3vF-lkp@intel.com/
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2024-12-19 18:05:04 +01:00
arch perf/x86/intel/pt: Fix buffer full but size is 0 case 2024-12-14 19:44:55 +01:00
block blk-iocost: Avoid using clamp() on inuse in __propagate_weights() 2024-12-19 18:05:04 +01:00
certs
crypto crypto: pcrypt - Call crypto layer directly when padata_do_parallel() return -EBUSY 2024-12-14 19:44:23 +01:00
Documentation PCI: Add 'reset_subordinate' to reset hierarchy below bridge 2024-12-14 19:44:54 +01:00
drivers ACPICA: events/evxfregn: don't release the ContextMutex that was never acquired 2024-12-19 18:05:04 +01:00
fs xfs: don't drop errno values when we fail to ficlone the entire range 2024-12-19 18:05:03 +01:00
include net: lapb: increase LAPB_HEADER_LEN 2024-12-19 18:05:03 +01:00
init initramfs: avoid filename buffer overrun 2024-12-14 19:44:21 +01:00
ipc
kernel bpf, xdp: Update devmap comments to reflect napi/rcu usage 2024-12-14 19:44:56 +01:00
lib lib: string_helpers: silence snprintf() output truncation warning 2024-12-14 19:44:39 +01:00
LICENSES
mm mm: revert "mm: shmem: fix data-race in shmem_getattr()" 2024-12-14 19:44:19 +01:00
net net/sched: netem: account for backlog updates from child qdisc 2024-12-19 18:05:04 +01:00
samples samples/bpf: Fix a resource leak 2024-12-14 19:44:50 +01:00
scripts modpost: Add .irqentry.text to OTHER_SECTIONS 2024-12-14 19:44:56 +01:00
security apparmor: fix 'Do simple duplicate message elimination' 2024-12-14 19:44:34 +01:00
sound ALSA: usb-audio: Fix out of bounds reads when finding clock sources 2024-12-14 19:44:56 +01:00
tools perf trace: Avoid garbage when not printing a syscall's arguments 2024-12-14 19:44:32 +01:00
usr
virt KVM: arm64: vgic-its: Clear ITE when DISCARD frees an ITE 2024-12-14 19:44:55 +01:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore Remove *.orig pattern from .gitignore 2024-11-08 16:20:33 +01:00
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS
Makefile Linux 5.4.287 2024-12-14 19:44:57 +01:00
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