Messages in this thread | | | Subject | Re: [PATCH] 2.4.18-pre9, trylock for read/write semaphores | Date | Wed, 13 Feb 2002 07:47:32 +0000 | From | David Howells <> |
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> > + new = old + RWSEM_ACTIVE_READ_BIAS; > > + if (cmpxchg(&sem->count, old, new) == old) > > + return 1; > > cmpxchg isnt present on i386
This isn't actually relevant... <asm/rwsem.h> isn't actually used unless CONFIG_RWSEM_GENERIC_SPINLOCK is turned off, which it isn't if the CPU type is configured to "i386":
[arch/i386/config.in] if [ "$CONFIG_M386" = "y" ]; then define_bool CONFIG_X86_CMPXCHG n define_bool CONFIG_X86_XADD n define_int CONFIG_X86_L1_CACHE_SHIFT 4 define_bool CONFIG_RWSEM_GENERIC_SPINLOCK y define_bool CONFIG_RWSEM_XCHGADD_ALGORITHM n else define_bool CONFIG_X86_WP_WORKS_OK y define_bool CONFIG_X86_INVLPG y define_bool CONFIG_X86_CMPXCHG y define_bool CONFIG_X86_XADD y define_bool CONFIG_X86_BSWAP y define_bool CONFIG_X86_POPAD_OK y define_bool CONFIG_RWSEM_GENERIC_SPINLOCK n define_bool CONFIG_RWSEM_XCHGADD_ALGORITHM y fi
[include/linux/rwsem.h] #ifdef CONFIG_RWSEM_GENERIC_SPINLOCK #include <linux/rwsem-spinlock.h> /* use a generic implementation */ #else #include <asm/rwsem.h> /* use an arch-specific implementation */ #endif
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