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d93cca2f31
Commit656e9007ef("asm-generic: avoid __generic_cmpxchg_local warnings") introduced a typo that means the code is incorrect for 32 bit values. It will work fine for postive numbers, but will fail for negative numbers on a system where longs are 64 bit. Fixes:656e9007ef("asm-generic: avoid __generic_cmpxchg_local warnings") Signed-off-by: David McKay <david.mckay@codasip.com> Signed-off-by: Stuart Menefy <stuart.menefy@codasip.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
68 lines
1.5 KiB
C
68 lines
1.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __ASM_GENERIC_CMPXCHG_LOCAL_H
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#define __ASM_GENERIC_CMPXCHG_LOCAL_H
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#include <linux/types.h>
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#include <linux/irqflags.h>
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extern unsigned long wrong_size_cmpxchg(volatile void *ptr)
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__noreturn;
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/*
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* Generic version of __cmpxchg_local (disables interrupts). Takes an unsigned
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* long parameter, supporting various types of architectures.
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*/
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static inline unsigned long __generic_cmpxchg_local(volatile void *ptr,
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unsigned long old, unsigned long new, int size)
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{
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unsigned long flags, prev;
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/*
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* Sanity checking, compile-time.
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*/
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if (size == 8 && sizeof(unsigned long) != 8)
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wrong_size_cmpxchg(ptr);
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raw_local_irq_save(flags);
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switch (size) {
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case 1: prev = *(u8 *)ptr;
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if (prev == (old & 0xffu))
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*(u8 *)ptr = (new & 0xffu);
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break;
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case 2: prev = *(u16 *)ptr;
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if (prev == (old & 0xffffu))
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*(u16 *)ptr = (new & 0xffffu);
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break;
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case 4: prev = *(u32 *)ptr;
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if (prev == (old & 0xffffffffu))
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*(u32 *)ptr = (new & 0xffffffffu);
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break;
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case 8: prev = *(u64 *)ptr;
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if (prev == old)
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*(u64 *)ptr = (u64)new;
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break;
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default:
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wrong_size_cmpxchg(ptr);
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}
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raw_local_irq_restore(flags);
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return prev;
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}
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/*
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* Generic version of __cmpxchg64_local. Takes an u64 parameter.
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*/
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static inline u64 __generic_cmpxchg64_local(volatile void *ptr,
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u64 old, u64 new)
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{
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u64 prev;
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unsigned long flags;
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raw_local_irq_save(flags);
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prev = *(u64 *)ptr;
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if (prev == old)
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*(u64 *)ptr = new;
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raw_local_irq_restore(flags);
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return prev;
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}
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#endif
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