include/asm-generic/cmpxchg-local.h:29:33: sparse: sparse: cast truncates bits from constant value (5f0ecafe becomes fe)
From: kernel test robot
Date: Sat Feb 25 2023 - 00:19:26 EST
tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: 489fa31ea873282b41046d412ec741f93946fc2d
commit: 6246541522845a443b7ae4a8f0e16facc5a91198 locking/atomic: cmpxchg: Make __generic_cmpxchg_local compare against zero-extended 'old' value
date: 3 weeks ago
config: csky-randconfig-s053-20230222 (https://download.01.org/0day-ci/archive/20230225/202302251316.oOXZoZwJ-lkp@xxxxxxxxx/config)
compiler: csky-linux-gcc (GCC) 12.1.0
reproduce:
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# apt-get install sparse
# sparse version: v0.6.4-39-gce1a6720-dirty
# https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=6246541522845a443b7ae4a8f0e16facc5a91198
git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
git fetch --no-tags linus master
git checkout 6246541522845a443b7ae4a8f0e16facc5a91198
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' O=build_dir ARCH=csky olddefconfig
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' O=build_dir ARCH=csky SHELL=/bin/bash fs/erofs/
If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@xxxxxxxxx>
| Link: https://lore.kernel.org/oe-kbuild-all/202302251316.oOXZoZwJ-lkp@xxxxxxxxx/
sparse warnings: (new ones prefixed by >>)
fs/erofs/zdata.c: note: in included file (through include/asm-generic/cmpxchg.h, arch/csky/include/asm/cmpxchg.h, include/asm-generic/atomic.h, ...):
include/asm-generic/cmpxchg-local.h:30:42: sparse: sparse: cast truncates bits from constant value (e0f510cc becomes cc)
include/asm-generic/cmpxchg-local.h:34:44: sparse: sparse: cast truncates bits from constant value (e0f510cc becomes 10cc)
>> include/asm-generic/cmpxchg-local.h:29:33: sparse: sparse: cast truncates bits from constant value (5f0ecafe becomes fe)
>> include/asm-generic/cmpxchg-local.h:33:34: sparse: sparse: cast truncates bits from constant value (5f0ecafe becomes cafe)
>> include/asm-generic/cmpxchg-local.h:29:33: sparse: sparse: cast truncates bits from constant value (5f0ecafe becomes fe)
include/asm-generic/cmpxchg-local.h:30:42: sparse: sparse: cast truncates bits from constant value (5f0edead becomes ad)
>> include/asm-generic/cmpxchg-local.h:33:34: sparse: sparse: cast truncates bits from constant value (5f0ecafe becomes cafe)
include/asm-generic/cmpxchg-local.h:34:44: sparse: sparse: cast truncates bits from constant value (5f0edead becomes dead)
vim +29 include/asm-generic/cmpxchg-local.h
7
8 extern unsigned long wrong_size_cmpxchg(volatile void *ptr)
9 __noreturn;
10
11 /*
12 * Generic version of __cmpxchg_local (disables interrupts). Takes an unsigned
13 * long parameter, supporting various types of architectures.
14 */
15 static inline unsigned long __generic_cmpxchg_local(volatile void *ptr,
16 unsigned long old, unsigned long new, int size)
17 {
18 unsigned long flags, prev;
19
20 /*
21 * Sanity checking, compile-time.
22 */
23 if (size == 8 && sizeof(unsigned long) != 8)
24 wrong_size_cmpxchg(ptr);
25
26 raw_local_irq_save(flags);
27 switch (size) {
28 case 1: prev = *(u8 *)ptr;
> 29 if (prev == (u8)old)
> 30 *(u8 *)ptr = (u8)new;
31 break;
32 case 2: prev = *(u16 *)ptr;
> 33 if (prev == (u16)old)
34 *(u16 *)ptr = (u16)new;
35 break;
36 case 4: prev = *(u32 *)ptr;
37 if (prev == (u32)old)
38 *(u32 *)ptr = (u32)new;
39 break;
40 case 8: prev = *(u64 *)ptr;
41 if (prev == old)
42 *(u64 *)ptr = (u64)new;
43 break;
44 default:
45 wrong_size_cmpxchg(ptr);
46 }
47 raw_local_irq_restore(flags);
48 return prev;
49 }
50
--
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