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Subject[tip:locking/core 9/11] include/asm-generic/atomic-instrumented.h:288:24: sparse: cast truncates bits from constant value (100 becomes 0)
tree:   https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git locking/core
head: ac605bee0bfab40fd5d11964705e907d2d5a32de
commit: 8bf705d130396e69c04cd8e6e010244ad2ce71f4 [9/11] locking/atomic/x86: Switch atomic.h to use atomic-instrumented.h
reproduce:
# apt-get install sparse
git checkout 8bf705d130396e69c04cd8e6e010244ad2ce71f4
make ARCH=x86_64 allmodconfig
make C=1 CF=-D__CHECK_ENDIAN__


sparse warnings: (new ones prefixed by >>)

kernel/locking/qspinlock.c:418:22: sparse: incorrect type in assignment (different modifiers) @@ expected struct mcs_spinlock *prev @@ got struct struct mcs_spinlock *prev @@
kernel/locking/qspinlock.c:418:22: expected struct mcs_spinlock *prev
kernel/locking/qspinlock.c:418:22: got struct mcs_spinlock [pure] *
kernel/locking/qspinlock_paravirt.h:519:1: sparse: symbol '__pv_queued_spin_unlock_slowpath' was not declared. Should it be static?
kernel/locking/qspinlock.c:418:22: sparse: incorrect type in assignment (different modifiers) @@ expected struct mcs_spinlock *prev @@ got struct struct mcs_spinlock *prev @@
kernel/locking/qspinlock.c:418:22: expected struct mcs_spinlock *prev
kernel/locking/qspinlock.c:418:22: got struct mcs_spinlock [pure] *
>> include/asm-generic/atomic-instrumented.h:288:24: sparse: cast truncates bits from constant value (100 becomes 0)

vim +288 include/asm-generic/atomic-instrumented.h

b06ed71a6 Dmitry Vyukov 2018-01-29 282
b06ed71a6 Dmitry Vyukov 2018-01-29 283 static __always_inline unsigned long
b06ed71a6 Dmitry Vyukov 2018-01-29 284 cmpxchg_size(volatile void *ptr, unsigned long old, unsigned long new, int size)
b06ed71a6 Dmitry Vyukov 2018-01-29 285 {
b06ed71a6 Dmitry Vyukov 2018-01-29 286 switch (size) {
b06ed71a6 Dmitry Vyukov 2018-01-29 287 case 1:
b06ed71a6 Dmitry Vyukov 2018-01-29 @288 return arch_cmpxchg((u8 *)ptr, (u8)old, (u8)new);
b06ed71a6 Dmitry Vyukov 2018-01-29 289 case 2:
b06ed71a6 Dmitry Vyukov 2018-01-29 290 return arch_cmpxchg((u16 *)ptr, (u16)old, (u16)new);
b06ed71a6 Dmitry Vyukov 2018-01-29 291 case 4:
b06ed71a6 Dmitry Vyukov 2018-01-29 292 return arch_cmpxchg((u32 *)ptr, (u32)old, (u32)new);
b06ed71a6 Dmitry Vyukov 2018-01-29 293 case 8:
b06ed71a6 Dmitry Vyukov 2018-01-29 294 BUILD_BUG_ON(sizeof(unsigned long) != 8);
b06ed71a6 Dmitry Vyukov 2018-01-29 295 return arch_cmpxchg((u64 *)ptr, (u64)old, (u64)new);
b06ed71a6 Dmitry Vyukov 2018-01-29 296 }
b06ed71a6 Dmitry Vyukov 2018-01-29 297 BUILD_BUG();
b06ed71a6 Dmitry Vyukov 2018-01-29 298 return 0;
b06ed71a6 Dmitry Vyukov 2018-01-29 299 }
b06ed71a6 Dmitry Vyukov 2018-01-29 300

:::::: The code at line 288 was first introduced by commit
:::::: b06ed71a624ba088a3e3e3ac7d4185f48c7c1660 locking/atomic, asm-generic: Add asm-generic/atomic-instrumented.h

:::::: TO: Dmitry Vyukov <dvyukov@google.com>
:::::: CC: Ingo Molnar <mingo@kernel.org>

---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation

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