函数逻辑报告

Linux Kernel

v5.5.9

Brick Technologies Co., Ltd

Source Code:kernel\locking\rwsem.c Create Date:2022-07-27 10:48:46
Last Modify:2020-03-12 14:18:49 Copyright©Brick
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函数名称：lock for writing

函数原型：static inline void __down_write(struct rw_semaphore *sem)

返回类型：void

参数：

类型参数名称
struct rw_semaphore *sem
1388  tmp等于RWSEM_UNLOCKED_VALUE
1390  如果此条件成立可能性小(为编译器优化)(!atomic_long_try_cmpxchg_acquire( & count, & tmp, On 64-bit architectures, the bit definitions of the count are:* Bit 0 - writer locked bit* Bit 1 - waiters present bit* Bit 2 - lock handoff bit* Bits 3-7 - reserved* Bits 8-62 - 55-bit reader count* Bit 63 - read fail bit* On 32-bit architectures, the ))则Wait until we successfully acquire the write lock
1393  否则All writes to owner are protected by WRITE_ONCE() to make sure that* store tearing can't happen as optimistic spinners may read and use* the owner value concurrently without lock