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/*
* Copyright (c) 2017 Cisco and/or its affiliates.
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef included_clib_lock_h
#define included_clib_lock_h
#include <vppinfra/clib.h>
#include <vppinfra/atomics.h>
#if __x86_64__
#define CLIB_PAUSE() __builtin_ia32_pause ()
#else
#define CLIB_PAUSE()
#endif
#if CLIB_DEBUG > 1
#define CLIB_LOCK_DBG(_p) \
do { \
(*_p)->frame_address = __builtin_frame_address (0); \
(*_p)->pid = getpid (); \
(*_p)->thread_index = os_get_thread_index (); \
} while (0)
#define CLIB_LOCK_DBG_CLEAR(_p) \
do { \
(*_p)->frame_address = 0; \
(*_p)->pid = 0; \
(*_p)->thread_index = 0; \
} while (0)
#else
#define CLIB_LOCK_DBG(_p)
#define CLIB_LOCK_DBG_CLEAR(_p)
#endif
#define CLIB_SPINLOCK_IS_LOCKED(_p) (*(_p))->lock
#define CLIB_SPINLOCK_ASSERT_LOCKED(_p) ASSERT(CLIB_SPINLOCK_IS_LOCKED((_p)))
typedef struct
{
CLIB_CACHE_LINE_ALIGN_MARK (cacheline0);
u32 lock;
#if CLIB_DEBUG > 0
pid_t pid;
uword thread_index;
void *frame_address;
#endif
} *clib_spinlock_t;
static inline void
clib_spinlock_init (clib_spinlock_t * p)
{
*p = clib_mem_alloc_aligned (CLIB_CACHE_LINE_BYTES, CLIB_CACHE_LINE_BYTES);
clib_memset ((void *) *p, 0, CLIB_CACHE_LINE_BYTES);
}
static inline void
clib_spinlock_free (clib_spinlock_t * p)
{
if (*p)
{
clib_mem_free ((void *) *p);
*p = 0;
}
}
static_always_inline void
clib_spinlock_lock (clib_spinlock_t * p)
{
u32 free = 0;
while (!clib_atomic_cmp_and_swap_acq_relax_n (&(*p)->lock, &free, 1, 0))
{
/* atomic load limits number of compare_exchange executions */
while (clib_atomic_load_relax_n (&(*p)->lock))
CLIB_PAUSE ();
/* on failure, compare_exchange writes (*p)->lock into free */
free = 0;
}
CLIB_LOCK_DBG (p);
}
static_always_inline void
clib_spinlock_lock_if_init (clib_spinlock_t * p)
{
if (PREDICT_FALSE (*p != 0))
clib_spinlock_lock (p);
}
static_always_inline void
clib_spinlock_unlock (clib_spinlock_t * p)
{
CLIB_LOCK_DBG_CLEAR (p);
/* Make sure all reads/writes are complete before releasing the lock */
clib_atomic_release (&(*p)->lock);
}
static_always_inline void
clib_spinlock_unlock_if_init (clib_spinlock_t * p)
{
if (PREDICT_FALSE (*p != 0))
clib_spinlock_unlock (p);
}
/*
* Readers-Writer Lock
*/
typedef struct clib_rw_lock_
{
CLIB_CACHE_LINE_ALIGN_MARK (cacheline0);
volatile u32 n_readers;
volatile u32 n_readers_lock;
volatile u32 writer_lock;
#if CLIB_DEBUG > 0
pid_t pid;
uword thread_index;
void *frame_address;
#endif
} *clib_rwlock_t;
always_inline void
clib_rwlock_init (clib_rwlock_t * p)
{
*p = clib_mem_alloc_aligned (CLIB_CACHE_LINE_BYTES, CLIB_CACHE_LINE_BYTES);
clib_memset ((void *) *p, 0, CLIB_CACHE_LINE_BYTES);
}
always_inline void
clib_rwlock_free (clib_rwlock_t * p)
{
if (*p)
{
clib_mem_free ((void *) *p);
*p = 0;
}
}
always_inline void
clib_rwlock_reader_lock (clib_rwlock_t * p)
{
while (clib_atomic_test_and_set (&(*p)->n_readers_lock))
CLIB_PAUSE ();
(*p)->n_readers += 1;
if ((*p)->n_readers == 1)
{
while (clib_atomic_test_and_set (&(*p)->writer_lock))
CLIB_PAUSE ();
}
clib_atomic_release (&(*p)->n_readers_lock);
CLIB_LOCK_DBG (p);
}
always_inline void
clib_rwlock_reader_unlock (clib_rwlock_t * p)
{
ASSERT ((*p)->n_readers > 0);
CLIB_LOCK_DBG_CLEAR (p);
while (clib_atomic_test_and_set (&(*p)->n_readers_lock))
CLIB_PAUSE ();
(*p)->n_readers -= 1;
if ((*p)->n_readers == 0)
{
clib_atomic_release (&(*p)->writer_lock);
}
clib_atomic_release (&(*p)->n_readers_lock);
}
always_inline void
clib_rwlock_writer_lock (clib_rwlock_t * p)
{
while (clib_atomic_test_and_set (&(*p)->writer_lock))
CLIB_PAUSE ();
CLIB_LOCK_DBG (p);
}
always_inline void
clib_rwlock_writer_unlock (clib_rwlock_t * p)
{
CLIB_LOCK_DBG_CLEAR (p);
clib_atomic_release (&(*p)->writer_lock);
}
#endif
/*
* fd.io coding-style-patch-verification: ON
*
* Local Variables:
* eval: (c-set-style "gnu")
* End:
*/
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