| /* |
| * Copyright 2011-2015 Samy Al Bahra. |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND |
| * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE |
| * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| * SUCH DAMAGE. |
| */ |
| |
| #ifndef CK_RWLOCK_H |
| #define CK_RWLOCK_H |
| |
| #include <ck_elide.h> |
| #include <ck_pr.h> |
| #include <ck_stdbool.h> |
| #include <ck_stddef.h> |
| |
| struct ck_rwlock { |
| unsigned int writer; |
| unsigned int n_readers; |
| }; |
| typedef struct ck_rwlock ck_rwlock_t; |
| |
| #define CK_RWLOCK_INITIALIZER {0, 0} |
| |
| CK_CC_INLINE static void |
| ck_rwlock_init(struct ck_rwlock *rw) |
| { |
| |
| rw->writer = 0; |
| rw->n_readers = 0; |
| ck_pr_barrier(); |
| return; |
| } |
| |
| CK_CC_INLINE static void |
| ck_rwlock_write_unlock(ck_rwlock_t *rw) |
| { |
| |
| ck_pr_fence_unlock(); |
| ck_pr_store_uint(&rw->writer, 0); |
| return; |
| } |
| |
| CK_CC_INLINE static bool |
| ck_rwlock_locked_writer(ck_rwlock_t *rw) |
| { |
| bool r; |
| |
| r = ck_pr_load_uint(&rw->writer); |
| ck_pr_fence_acquire(); |
| return r; |
| } |
| |
| CK_CC_INLINE static void |
| ck_rwlock_write_downgrade(ck_rwlock_t *rw) |
| { |
| |
| ck_pr_inc_uint(&rw->n_readers); |
| ck_rwlock_write_unlock(rw); |
| return; |
| } |
| |
| CK_CC_INLINE static bool |
| ck_rwlock_locked(ck_rwlock_t *rw) |
| { |
| bool l; |
| |
| l = ck_pr_load_uint(&rw->n_readers) | |
| ck_pr_load_uint(&rw->writer); |
| ck_pr_fence_acquire(); |
| return l; |
| } |
| |
| CK_CC_INLINE static bool |
| ck_rwlock_write_trylock(ck_rwlock_t *rw) |
| { |
| |
| if (ck_pr_fas_uint(&rw->writer, 1) != 0) |
| return false; |
| |
| ck_pr_fence_atomic_load(); |
| |
| if (ck_pr_load_uint(&rw->n_readers) != 0) { |
| ck_rwlock_write_unlock(rw); |
| return false; |
| } |
| |
| ck_pr_fence_lock(); |
| return true; |
| } |
| |
| CK_ELIDE_TRYLOCK_PROTOTYPE(ck_rwlock_write, ck_rwlock_t, |
| ck_rwlock_locked, ck_rwlock_write_trylock) |
| |
| CK_CC_INLINE static void |
| ck_rwlock_write_lock(ck_rwlock_t *rw) |
| { |
| |
| while (ck_pr_fas_uint(&rw->writer, 1) != 0) |
| ck_pr_stall(); |
| |
| ck_pr_fence_atomic_load(); |
| |
| while (ck_pr_load_uint(&rw->n_readers) != 0) |
| ck_pr_stall(); |
| |
| ck_pr_fence_lock(); |
| return; |
| } |
| |
| CK_ELIDE_PROTOTYPE(ck_rwlock_write, ck_rwlock_t, |
| ck_rwlock_locked, ck_rwlock_write_lock, |
| ck_rwlock_locked_writer, ck_rwlock_write_unlock) |
| |
| CK_CC_INLINE static bool |
| ck_rwlock_read_trylock(ck_rwlock_t *rw) |
| { |
| |
| if (ck_pr_load_uint(&rw->writer) != 0) |
| return false; |
| |
| ck_pr_inc_uint(&rw->n_readers); |
| |
| /* |
| * Serialize with respect to concurrent write |
| * lock operation. |
| */ |
| ck_pr_fence_atomic_load(); |
| |
| if (ck_pr_load_uint(&rw->writer) == 0) { |
| ck_pr_fence_lock(); |
| return true; |
| } |
| |
| ck_pr_dec_uint(&rw->n_readers); |
| return false; |
| } |
| |
| CK_ELIDE_TRYLOCK_PROTOTYPE(ck_rwlock_read, ck_rwlock_t, |
| ck_rwlock_locked_writer, ck_rwlock_read_trylock) |
| |
| CK_CC_INLINE static void |
| ck_rwlock_read_lock(ck_rwlock_t *rw) |
| { |
| |
| for (;;) { |
| while (ck_pr_load_uint(&rw->writer) != 0) |
| ck_pr_stall(); |
| |
| ck_pr_inc_uint(&rw->n_readers); |
| |
| /* |
| * Serialize with respect to concurrent write |
| * lock operation. |
| */ |
| ck_pr_fence_atomic_load(); |
| |
| if (ck_pr_load_uint(&rw->writer) == 0) |
| break; |
| |
| ck_pr_dec_uint(&rw->n_readers); |
| } |
| |
| /* Acquire semantics are necessary. */ |
| ck_pr_fence_load(); |
| return; |
| } |
| |
| CK_CC_INLINE static bool |
| ck_rwlock_locked_reader(ck_rwlock_t *rw) |
| { |
| |
| ck_pr_fence_load(); |
| return ck_pr_load_uint(&rw->n_readers); |
| } |
| |
| CK_CC_INLINE static void |
| ck_rwlock_read_unlock(ck_rwlock_t *rw) |
| { |
| |
| ck_pr_fence_load_atomic(); |
| ck_pr_dec_uint(&rw->n_readers); |
| return; |
| } |
| |
| CK_ELIDE_PROTOTYPE(ck_rwlock_read, ck_rwlock_t, |
| ck_rwlock_locked_writer, ck_rwlock_read_lock, |
| ck_rwlock_locked_reader, ck_rwlock_read_unlock) |
| |
| /* |
| * Recursive writer reader-writer lock implementation. |
| */ |
| struct ck_rwlock_recursive { |
| struct ck_rwlock rw; |
| unsigned int wc; |
| }; |
| typedef struct ck_rwlock_recursive ck_rwlock_recursive_t; |
| |
| #define CK_RWLOCK_RECURSIVE_INITIALIZER {CK_RWLOCK_INITIALIZER, 0} |
| |
| CK_CC_INLINE static void |
| ck_rwlock_recursive_write_lock(ck_rwlock_recursive_t *rw, unsigned int tid) |
| { |
| unsigned int o; |
| |
| o = ck_pr_load_uint(&rw->rw.writer); |
| if (o == tid) |
| goto leave; |
| |
| while (ck_pr_cas_uint(&rw->rw.writer, 0, tid) == false) |
| ck_pr_stall(); |
| |
| ck_pr_fence_atomic_load(); |
| |
| while (ck_pr_load_uint(&rw->rw.n_readers) != 0) |
| ck_pr_stall(); |
| |
| ck_pr_fence_lock(); |
| leave: |
| rw->wc++; |
| return; |
| } |
| |
| CK_CC_INLINE static bool |
| ck_rwlock_recursive_write_trylock(ck_rwlock_recursive_t *rw, unsigned int tid) |
| { |
| unsigned int o; |
| |
| o = ck_pr_load_uint(&rw->rw.writer); |
| if (o == tid) |
| goto leave; |
| |
| if (ck_pr_cas_uint(&rw->rw.writer, 0, tid) == false) |
| return false; |
| |
| ck_pr_fence_atomic_load(); |
| |
| if (ck_pr_load_uint(&rw->rw.n_readers) != 0) { |
| ck_pr_store_uint(&rw->rw.writer, 0); |
| return false; |
| } |
| |
| ck_pr_fence_lock(); |
| leave: |
| rw->wc++; |
| return true; |
| } |
| |
| CK_CC_INLINE static void |
| ck_rwlock_recursive_write_unlock(ck_rwlock_recursive_t *rw) |
| { |
| |
| if (--rw->wc == 0) { |
| ck_pr_fence_unlock(); |
| ck_pr_store_uint(&rw->rw.writer, 0); |
| } |
| |
| return; |
| } |
| |
| CK_CC_INLINE static void |
| ck_rwlock_recursive_read_lock(ck_rwlock_recursive_t *rw) |
| { |
| |
| ck_rwlock_read_lock(&rw->rw); |
| return; |
| } |
| |
| CK_CC_INLINE static bool |
| ck_rwlock_recursive_read_trylock(ck_rwlock_recursive_t *rw) |
| { |
| |
| return ck_rwlock_read_trylock(&rw->rw); |
| } |
| |
| CK_CC_INLINE static void |
| ck_rwlock_recursive_read_unlock(ck_rwlock_recursive_t *rw) |
| { |
| |
| ck_rwlock_read_unlock(&rw->rw); |
| return; |
| } |
| |
| #endif /* CK_RWLOCK_H */ |