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https://github.com/zephyrproject-rtos/zephyr
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820c94e5dd
The xtensa atomics layer was written with hand-coded assembly that had to be called as functions. That's needlessly slow, given that the low level primitives are a two-instruction sequence. Ideally the compiler should see this as an inline to permit it to better optimize around the needed barriers. There was also a bug with the atomic_cas function, which had a loop internally instead of returning the old value synchronously on a failed swap. That's benign right now because our existing spin lock does nothing but retry it in a tight loop anyway, but it's incorrect per spec and would have caused a contention hang with more elaborate algorithms (for example a spinlock with backoff semantics). Remove the old implementation and replace with a much smaller inline C one based on just two assembly primitives. This patch also contains a little bit of refactoring to address the scheme has been split out into a separate header for each, and the ATOMIC_OPERATIONS_CUSTOM kconfig has been renamed to ATOMIC_OPERATIONS_ARCH to better capture what it means. Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
79 lines
1.8 KiB
C
79 lines
1.8 KiB
C
/*
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* Copyright (c) 1997-2015, Wind River Systems, Inc.
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#ifndef ZEPHYR_INCLUDE_SYS_ATOMIC_C_H_
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#define ZEPHYR_INCLUDE_SYS_ATOMIC_C_H_
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/* Included from <atomic.h> */
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#ifdef __cplusplus
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extern "C" {
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#endif
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/* Simple and correct (but very slow) implementation of atomic
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* primitives that require nothing more than kernel interrupt locking.
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*/
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__syscall bool atomic_cas(atomic_t *target, atomic_val_t old_value,
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atomic_val_t new_value);
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__syscall bool atomic_ptr_cas(atomic_ptr_t *target, void *old_value,
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void *new_value);
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__syscall atomic_val_t atomic_add(atomic_t *target, atomic_val_t value);
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__syscall atomic_val_t atomic_sub(atomic_t *target, atomic_val_t value);
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static inline atomic_val_t atomic_inc(atomic_t *target)
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{
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return atomic_add(target, 1);
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}
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static inline atomic_val_t atomic_dec(atomic_t *target)
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{
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return atomic_sub(target, 1);
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}
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extern atomic_val_t atomic_get(const atomic_t *target);
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extern void *atomic_ptr_get(const atomic_ptr_t *target);
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__syscall atomic_val_t atomic_set(atomic_t *target, atomic_val_t value);
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__syscall void *atomic_ptr_set(atomic_ptr_t *target, void *value);
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static inline atomic_val_t atomic_clear(atomic_t *target)
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{
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return atomic_set(target, 0);
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}
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static inline void *atomic_ptr_clear(atomic_ptr_t *target)
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{
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return atomic_ptr_set(target, NULL);
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}
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__syscall atomic_val_t atomic_or(atomic_t *target, atomic_val_t value);
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__syscall atomic_val_t atomic_xor(atomic_t *target, atomic_val_t value);
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__syscall atomic_val_t atomic_and(atomic_t *target, atomic_val_t value);
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__syscall atomic_val_t atomic_nand(atomic_t *target, atomic_val_t value);
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#ifdef __cplusplus
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}
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#endif
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#ifdef CONFIG_ATOMIC_OPERATIONS_C
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#include <syscalls/atomic_c.h>
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#endif
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#endif /* ZEPHYR_INCLUDE_SYS_ATOMIC_C_H_ */
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