| /* |
| * Copyright 2010-2015 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_SPINLOCK_TICKET_H |
| #define CK_SPINLOCK_TICKET_H |
| |
| #include <ck_backoff.h> |
| #include <ck_cc.h> |
| #include <ck_elide.h> |
| #include <ck_md.h> |
| #include <ck_pr.h> |
| #include <ck_stdbool.h> |
| |
| #ifndef CK_F_SPINLOCK_TICKET |
| #define CK_F_SPINLOCK_TICKET |
| /* |
| * If 16-bit or 32-bit increment is supported, implement support for |
| * trylock functionality on availability of 32-bit or 64-bit fetch-and-add |
| * and compare-and-swap. This code path is only applied to x86*. |
| */ |
| #if defined(CK_MD_TSO) && (defined(__x86__) || defined(__x86_64__)) |
| #if defined(CK_F_PR_FAA_32) && defined(CK_F_PR_INC_16) && defined(CK_F_PR_CAS_32) |
| #define CK_SPINLOCK_TICKET_TYPE uint32_t |
| #define CK_SPINLOCK_TICKET_TYPE_BASE uint16_t |
| #define CK_SPINLOCK_TICKET_INC(x) ck_pr_inc_16(x) |
| #define CK_SPINLOCK_TICKET_CAS(x, y, z) ck_pr_cas_32(x, y, z) |
| #define CK_SPINLOCK_TICKET_FAA(x, y) ck_pr_faa_32(x, y) |
| #define CK_SPINLOCK_TICKET_LOAD(x) ck_pr_load_32(x) |
| #define CK_SPINLOCK_TICKET_INCREMENT (0x00010000UL) |
| #define CK_SPINLOCK_TICKET_MASK (0xFFFFUL) |
| #define CK_SPINLOCK_TICKET_SHIFT (16) |
| #elif defined(CK_F_PR_FAA_64) && defined(CK_F_PR_INC_32) && defined(CK_F_PR_CAS_64) |
| #define CK_SPINLOCK_TICKET_TYPE uint64_t |
| #define CK_SPINLOCK_TICKET_TYPE_BASE uint32_t |
| #define CK_SPINLOCK_TICKET_INC(x) ck_pr_inc_32(x) |
| #define CK_SPINLOCK_TICKET_CAS(x, y, z) ck_pr_cas_64(x, y, z) |
| #define CK_SPINLOCK_TICKET_FAA(x, y) ck_pr_faa_64(x, y) |
| #define CK_SPINLOCK_TICKET_LOAD(x) ck_pr_load_64(x) |
| #define CK_SPINLOCK_TICKET_INCREMENT (0x0000000100000000ULL) |
| #define CK_SPINLOCK_TICKET_MASK (0xFFFFFFFFULL) |
| #define CK_SPINLOCK_TICKET_SHIFT (32) |
| #endif |
| #endif /* CK_MD_TSO */ |
| |
| #if defined(CK_SPINLOCK_TICKET_TYPE) |
| #define CK_F_SPINLOCK_TICKET_TRYLOCK |
| |
| struct ck_spinlock_ticket { |
| CK_SPINLOCK_TICKET_TYPE value; |
| }; |
| typedef struct ck_spinlock_ticket ck_spinlock_ticket_t; |
| #define CK_SPINLOCK_TICKET_INITIALIZER { .value = 0 } |
| |
| CK_CC_INLINE static void |
| ck_spinlock_ticket_init(struct ck_spinlock_ticket *ticket) |
| { |
| |
| ticket->value = 0; |
| ck_pr_barrier(); |
| return; |
| } |
| |
| CK_CC_INLINE static bool |
| ck_spinlock_ticket_locked(struct ck_spinlock_ticket *ticket) |
| { |
| CK_SPINLOCK_TICKET_TYPE request, position; |
| |
| request = CK_SPINLOCK_TICKET_LOAD(&ticket->value); |
| position = request & CK_SPINLOCK_TICKET_MASK; |
| request >>= CK_SPINLOCK_TICKET_SHIFT; |
| |
| ck_pr_fence_acquire(); |
| return request != position; |
| } |
| |
| CK_CC_INLINE static void |
| ck_spinlock_ticket_lock(struct ck_spinlock_ticket *ticket) |
| { |
| CK_SPINLOCK_TICKET_TYPE request, position; |
| |
| /* Get our ticket number and set next ticket number. */ |
| request = CK_SPINLOCK_TICKET_FAA(&ticket->value, |
| CK_SPINLOCK_TICKET_INCREMENT); |
| |
| position = request & CK_SPINLOCK_TICKET_MASK; |
| request >>= CK_SPINLOCK_TICKET_SHIFT; |
| |
| while (request != position) { |
| ck_pr_stall(); |
| position = CK_SPINLOCK_TICKET_LOAD(&ticket->value) & |
| CK_SPINLOCK_TICKET_MASK; |
| } |
| |
| ck_pr_fence_lock(); |
| return; |
| } |
| |
| CK_CC_INLINE static void |
| ck_spinlock_ticket_lock_pb(struct ck_spinlock_ticket *ticket, unsigned int c) |
| { |
| CK_SPINLOCK_TICKET_TYPE request, position; |
| ck_backoff_t backoff; |
| |
| /* Get our ticket number and set next ticket number. */ |
| request = CK_SPINLOCK_TICKET_FAA(&ticket->value, |
| CK_SPINLOCK_TICKET_INCREMENT); |
| |
| position = request & CK_SPINLOCK_TICKET_MASK; |
| request >>= CK_SPINLOCK_TICKET_SHIFT; |
| |
| while (request != position) { |
| ck_pr_stall(); |
| position = CK_SPINLOCK_TICKET_LOAD(&ticket->value) & |
| CK_SPINLOCK_TICKET_MASK; |
| |
| backoff = (request - position) & CK_SPINLOCK_TICKET_MASK; |
| backoff <<= c; |
| ck_backoff_eb(&backoff); |
| } |
| |
| ck_pr_fence_lock(); |
| return; |
| } |
| |
| CK_CC_INLINE static bool |
| ck_spinlock_ticket_trylock(struct ck_spinlock_ticket *ticket) |
| { |
| CK_SPINLOCK_TICKET_TYPE snapshot, request, position; |
| |
| snapshot = CK_SPINLOCK_TICKET_LOAD(&ticket->value); |
| position = snapshot & CK_SPINLOCK_TICKET_MASK; |
| request = snapshot >> CK_SPINLOCK_TICKET_SHIFT; |
| |
| if (position != request) |
| return false; |
| |
| if (CK_SPINLOCK_TICKET_CAS(&ticket->value, |
| snapshot, snapshot + CK_SPINLOCK_TICKET_INCREMENT) == false) { |
| return false; |
| } |
| |
| ck_pr_fence_lock(); |
| return true; |
| } |
| |
| CK_CC_INLINE static void |
| ck_spinlock_ticket_unlock(struct ck_spinlock_ticket *ticket) |
| { |
| |
| ck_pr_fence_unlock(); |
| CK_SPINLOCK_TICKET_INC((CK_SPINLOCK_TICKET_TYPE_BASE *)(void *)&ticket->value); |
| return; |
| } |
| |
| #undef CK_SPINLOCK_TICKET_TYPE |
| #undef CK_SPINLOCK_TICKET_TYPE_BASE |
| #undef CK_SPINLOCK_TICKET_INC |
| #undef CK_SPINLOCK_TICKET_FAA |
| #undef CK_SPINLOCK_TICKET_LOAD |
| #undef CK_SPINLOCK_TICKET_INCREMENT |
| #undef CK_SPINLOCK_TICKET_MASK |
| #undef CK_SPINLOCK_TICKET_SHIFT |
| #else |
| /* |
| * MESI benefits from cacheline padding between next and current. This avoids |
| * invalidation of current from the cache due to incoming lock requests. |
| */ |
| struct ck_spinlock_ticket { |
| unsigned int next; |
| unsigned int position; |
| }; |
| typedef struct ck_spinlock_ticket ck_spinlock_ticket_t; |
| |
| #define CK_SPINLOCK_TICKET_INITIALIZER {.next = 0, .position = 0} |
| |
| CK_CC_INLINE static void |
| ck_spinlock_ticket_init(struct ck_spinlock_ticket *ticket) |
| { |
| |
| ticket->next = 0; |
| ticket->position = 0; |
| ck_pr_barrier(); |
| |
| return; |
| } |
| |
| CK_CC_INLINE static bool |
| ck_spinlock_ticket_locked(struct ck_spinlock_ticket *ticket) |
| { |
| bool r; |
| |
| r = ck_pr_load_uint(&ticket->position) != |
| ck_pr_load_uint(&ticket->next); |
| ck_pr_fence_acquire(); |
| return r; |
| } |
| |
| CK_CC_INLINE static void |
| ck_spinlock_ticket_lock(struct ck_spinlock_ticket *ticket) |
| { |
| unsigned int request; |
| |
| /* Get our ticket number and set next ticket number. */ |
| request = ck_pr_faa_uint(&ticket->next, 1); |
| |
| /* |
| * Busy-wait until our ticket number is current. |
| * We can get away without a fence here assuming |
| * our position counter does not overflow. |
| */ |
| while (ck_pr_load_uint(&ticket->position) != request) |
| ck_pr_stall(); |
| |
| ck_pr_fence_lock(); |
| return; |
| } |
| |
| CK_CC_INLINE static void |
| ck_spinlock_ticket_lock_pb(struct ck_spinlock_ticket *ticket, unsigned int c) |
| { |
| ck_backoff_t backoff; |
| unsigned int request, position; |
| |
| request = ck_pr_faa_uint(&ticket->next, 1); |
| |
| for (;;) { |
| position = ck_pr_load_uint(&ticket->position); |
| if (position == request) |
| break; |
| |
| backoff = request - position; |
| backoff <<= c; |
| |
| /* |
| * Ideally, back-off from generating cache traffic for at least |
| * the amount of time necessary for the number of pending lock |
| * acquisition and relinquish operations (assuming an empty |
| * critical section). |
| */ |
| ck_backoff_eb(&backoff); |
| } |
| |
| ck_pr_fence_lock(); |
| return; |
| } |
| |
| CK_CC_INLINE static void |
| ck_spinlock_ticket_unlock(struct ck_spinlock_ticket *ticket) |
| { |
| unsigned int update; |
| |
| ck_pr_fence_unlock(); |
| |
| /* |
| * Update current ticket value so next lock request can proceed. |
| * Overflow behavior is assumed to be roll-over, in which case, |
| * it is only an issue if there are 2^32 pending lock requests. |
| */ |
| update = ck_pr_load_uint(&ticket->position); |
| ck_pr_store_uint(&ticket->position, update + 1); |
| return; |
| } |
| #endif /* !CK_F_SPINLOCK_TICKET_TRYLOCK */ |
| |
| CK_ELIDE_PROTOTYPE(ck_spinlock_ticket, ck_spinlock_ticket_t, |
| ck_spinlock_ticket_locked, ck_spinlock_ticket_lock, |
| ck_spinlock_ticket_locked, ck_spinlock_ticket_unlock) |
| |
| CK_ELIDE_TRYLOCK_PROTOTYPE(ck_spinlock_ticket, ck_spinlock_ticket_t, |
| ck_spinlock_ticket_locked, ck_spinlock_ticket_trylock) |
| |
| #endif /* CK_F_SPINLOCK_TICKET */ |
| #endif /* CK_SPINLOCK_TICKET_H */ |