diff options
author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 15:20:36 -0700 |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 15:20:36 -0700 |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /include/asm-sparc64/rwsem.h |
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Diffstat (limited to 'include/asm-sparc64/rwsem.h')
-rw-r--r-- | include/asm-sparc64/rwsem.h | 100 |
1 files changed, 100 insertions, 0 deletions
diff --git a/include/asm-sparc64/rwsem.h b/include/asm-sparc64/rwsem.h new file mode 100644 index 00000000000..bf2ae90ed3d --- /dev/null +++ b/include/asm-sparc64/rwsem.h @@ -0,0 +1,100 @@ +/* $Id: rwsem.h,v 1.5 2001/11/18 00:12:56 davem Exp $ + * rwsem.h: R/W semaphores implemented using CAS + * + * Written by David S. Miller (davem@redhat.com), 2001. + * Derived from asm-i386/rwsem.h + */ +#ifndef _SPARC64_RWSEM_H +#define _SPARC64_RWSEM_H + +#ifndef _LINUX_RWSEM_H +#error "please don't include asm/rwsem.h directly, use linux/rwsem.h instead" +#endif + +#ifdef __KERNEL__ + +#include <linux/list.h> +#include <linux/spinlock.h> +#include <asm/rwsem-const.h> + +struct rwsem_waiter; + +struct rw_semaphore { + signed int count; + spinlock_t wait_lock; + struct list_head wait_list; +}; + +#define __RWSEM_INITIALIZER(name) \ +{ RWSEM_UNLOCKED_VALUE, SPIN_LOCK_UNLOCKED, LIST_HEAD_INIT((name).wait_list) } + +#define DECLARE_RWSEM(name) \ + struct rw_semaphore name = __RWSEM_INITIALIZER(name) + +static __inline__ void init_rwsem(struct rw_semaphore *sem) +{ + sem->count = RWSEM_UNLOCKED_VALUE; + spin_lock_init(&sem->wait_lock); + INIT_LIST_HEAD(&sem->wait_list); +} + +extern void __down_read(struct rw_semaphore *sem); +extern int __down_read_trylock(struct rw_semaphore *sem); +extern void __down_write(struct rw_semaphore *sem); +extern int __down_write_trylock(struct rw_semaphore *sem); +extern void __up_read(struct rw_semaphore *sem); +extern void __up_write(struct rw_semaphore *sem); +extern void __downgrade_write(struct rw_semaphore *sem); + +static __inline__ int rwsem_atomic_update(int delta, struct rw_semaphore *sem) +{ + int tmp = delta; + + __asm__ __volatile__( + "1:\tlduw [%2], %%g1\n\t" + "add %%g1, %1, %%g7\n\t" + "cas [%2], %%g1, %%g7\n\t" + "cmp %%g1, %%g7\n\t" + "bne,pn %%icc, 1b\n\t" + " membar #StoreLoad | #StoreStore\n\t" + "mov %%g7, %0\n\t" + : "=&r" (tmp) + : "0" (tmp), "r" (sem) + : "g1", "g7", "memory", "cc"); + + return tmp + delta; +} + +#define rwsem_atomic_add rwsem_atomic_update + +static __inline__ __u16 rwsem_cmpxchgw(struct rw_semaphore *sem, __u16 __old, __u16 __new) +{ + u32 old = (sem->count & 0xffff0000) | (u32) __old; + u32 new = (old & 0xffff0000) | (u32) __new; + u32 prev; + +again: + __asm__ __volatile__("cas [%2], %3, %0\n\t" + "membar #StoreLoad | #StoreStore" + : "=&r" (prev) + : "0" (new), "r" (sem), "r" (old) + : "memory"); + + /* To give the same semantics as x86 cmpxchgw, keep trying + * if only the upper 16-bits changed. + */ + if (prev != old && + ((prev & 0xffff) == (old & 0xffff))) + goto again; + + return prev & 0xffff; +} + +static __inline__ signed long rwsem_cmpxchg(struct rw_semaphore *sem, signed long old, signed long new) +{ + return cmpxchg(&sem->count,old,new); +} + +#endif /* __KERNEL__ */ + +#endif /* _SPARC64_RWSEM_H */ |