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X-Received-From: 209.132.183.28 Cc: kwolf@redhat.com, qemu-devel@nongnu.org Subject: [Qemu-devel] [PATCH 01/30] coroutine: Add CoRwlock support X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org From: "Aneesh Kumar K.V" Signed-off-by: Aneesh Kumar K.V Signed-off-by: Kevin Wolf --- qemu-coroutine-lock.c | 44 ++++++++++++++++++++++++++++++++++++++++++++ qemu-coroutine.h | 32 ++++++++++++++++++++++++++++++++ 2 files changed, 76 insertions(+), 0 deletions(-) diff --git a/qemu-coroutine-lock.c b/qemu-coroutine-lock.c index a80f437..2a385a3 100644 --- a/qemu-coroutine-lock.c +++ b/qemu-coroutine-lock.c @@ -115,3 +115,47 @@ void coroutine_fn qemu_co_mutex_unlock(CoMutex *mutex) trace_qemu_co_mutex_unlock_return(mutex, self); } + +void qemu_co_rwlock_init(CoRwlock *lock) +{ + memset(lock, 0, sizeof(*lock)); + qemu_co_queue_init(&lock->queue); +} + +void qemu_co_rwlock_rdlock(CoRwlock *lock) +{ + while (lock->writer) { + qemu_co_queue_wait(&lock->queue); + } + lock->reader++; +} + +void qemu_co_rwlock_unlock(CoRwlock *lock) +{ + assert(qemu_in_coroutine()); + if (lock->writer) { + lock->writer = false; + while (!qemu_co_queue_empty(&lock->queue)) { + /* + * Wakeup every body. This will include some + * writers too. + */ + qemu_co_queue_next(&lock->queue); + } + } else { + lock->reader--; + assert(lock->reader >= 0); + /* Wakeup only one waiting writer */ + if (!lock->reader) { + qemu_co_queue_next(&lock->queue); + } + } +} + +void qemu_co_rwlock_wrlock(CoRwlock *lock) +{ + while (lock->writer || lock->reader) { + qemu_co_queue_wait(&lock->queue); + } + lock->writer = true; +} diff --git a/qemu-coroutine.h b/qemu-coroutine.h index 2f2fd95..b8fc4f4 100644 --- a/qemu-coroutine.h +++ b/qemu-coroutine.h @@ -156,4 +156,36 @@ void coroutine_fn qemu_co_mutex_lock(CoMutex *mutex); */ void coroutine_fn qemu_co_mutex_unlock(CoMutex *mutex); +typedef struct CoRwlock { + bool writer; + int reader; + CoQueue queue; +} CoRwlock; + +/** + * Initialises a CoRwlock. This must be called before any other operation + * is used on the CoRwlock + */ +void qemu_co_rwlock_init(CoRwlock *lock); + +/** + * Read locks the CoRwlock. If the lock cannot be taken immediately because + * of a parallel writer, control is transferred to the caller of the current + * coroutine. + */ +void qemu_co_rwlock_rdlock(CoRwlock *lock); + +/** + * Write Locks the mutex. If the lock cannot be taken immediately because + * of a parallel reader, control is transferred to the caller of the current + * coroutine. + */ +void qemu_co_rwlock_wrlock(CoRwlock *lock); + +/** + * Unlocks the read/write lock and schedules the next coroutine that was + * waiting for this lock to be run. + */ +void qemu_co_rwlock_unlock(CoRwlock *lock); + #endif /* QEMU_COROUTINE_H */