aio: convert from RFifoLock to QemuRecMutex
It is simpler and a bit faster, and QEMU does not need the contention
callbacks (and thus the fairness) anymore.
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1477565348-5458-21-git-send-email-pbonzini@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
diff --git a/async.c b/async.c
index 27db772..b2de360 100644
--- a/async.c
+++ b/async.c
@@ -284,7 +284,7 @@
aio_set_event_notifier(ctx, &ctx->notifier, false, NULL);
event_notifier_cleanup(&ctx->notifier);
- rfifolock_destroy(&ctx->lock);
+ qemu_rec_mutex_destroy(&ctx->lock);
qemu_mutex_destroy(&ctx->bh_lock);
timerlistgroup_deinit(&ctx->tlg);
}
@@ -372,7 +372,7 @@
#endif
ctx->thread_pool = NULL;
qemu_mutex_init(&ctx->bh_lock);
- rfifolock_init(&ctx->lock, NULL, NULL);
+ qemu_rec_mutex_init(&ctx->lock);
timerlistgroup_init(&ctx->tlg, aio_timerlist_notify, ctx);
return ctx;
@@ -393,10 +393,10 @@
void aio_context_acquire(AioContext *ctx)
{
- rfifolock_lock(&ctx->lock);
+ qemu_rec_mutex_lock(&ctx->lock);
}
void aio_context_release(AioContext *ctx)
{
- rfifolock_unlock(&ctx->lock);
+ qemu_rec_mutex_unlock(&ctx->lock);
}
diff --git a/include/block/aio.h b/include/block/aio.h
index 8e1885b..c7ae27c 100644
--- a/include/block/aio.h
+++ b/include/block/aio.h
@@ -18,7 +18,6 @@
#include "qemu/queue.h"
#include "qemu/event_notifier.h"
#include "qemu/thread.h"
-#include "qemu/rfifolock.h"
#include "qemu/timer.h"
typedef struct BlockAIOCB BlockAIOCB;
@@ -54,7 +53,7 @@
GSource source;
/* Protects all fields from multi-threaded access */
- RFifoLock lock;
+ QemuRecMutex lock;
/* The list of registered AIO handlers */
QLIST_HEAD(, AioHandler) aio_handlers;
diff --git a/include/qemu/rfifolock.h b/include/qemu/rfifolock.h
deleted file mode 100644
index b23ab53..0000000
--- a/include/qemu/rfifolock.h
+++ /dev/null
@@ -1,54 +0,0 @@
-/*
- * Recursive FIFO lock
- *
- * Copyright Red Hat, Inc. 2013
- *
- * Authors:
- * Stefan Hajnoczi <stefanha@redhat.com>
- *
- * This work is licensed under the terms of the GNU GPL, version 2 or later.
- * See the COPYING file in the top-level directory.
- *
- */
-
-#ifndef QEMU_RFIFOLOCK_H
-#define QEMU_RFIFOLOCK_H
-
-#include "qemu/thread.h"
-
-/* Recursive FIFO lock
- *
- * This lock provides more features than a plain mutex:
- *
- * 1. Fairness - enforces FIFO order.
- * 2. Nesting - can be taken recursively.
- * 3. Contention callback - optional, called when thread must wait.
- *
- * The recursive FIFO lock is heavyweight so prefer other synchronization
- * primitives if you do not need its features.
- */
-typedef struct {
- QemuMutex lock; /* protects all fields */
-
- /* FIFO order */
- unsigned int head; /* active ticket number */
- unsigned int tail; /* waiting ticket number */
- QemuCond cond; /* used to wait for our ticket number */
-
- /* Nesting */
- QemuThread owner_thread; /* thread that currently has ownership */
- unsigned int nesting; /* amount of nesting levels */
-
- /* Contention callback */
- void (*cb)(void *); /* called when thread must wait, with ->lock
- * held so it may not recursively lock/unlock
- */
- void *cb_opaque;
-} RFifoLock;
-
-void rfifolock_init(RFifoLock *r, void (*cb)(void *), void *opaque);
-void rfifolock_destroy(RFifoLock *r);
-void rfifolock_lock(RFifoLock *r);
-void rfifolock_unlock(RFifoLock *r);
-
-#endif /* QEMU_RFIFOLOCK_H */
diff --git a/tests/.gitignore b/tests/.gitignore
index 64e050e..c0d7857 100644
--- a/tests/.gitignore
+++ b/tests/.gitignore
@@ -67,7 +67,6 @@
test-qobject-output-visitor
test-rcu-list
test-replication
-test-rfifolock
test-string-input-visitor
test-string-output-visitor
test-thread-pool
diff --git a/tests/Makefile.include b/tests/Makefile.include
index 22656ea..04108df 100644
--- a/tests/Makefile.include
+++ b/tests/Makefile.include
@@ -45,7 +45,6 @@
check-unit-y += tests/test-iov$(EXESUF)
gcov-files-test-iov-y = util/iov.c
check-unit-y += tests/test-aio$(EXESUF)
-check-unit-$(CONFIG_POSIX) += tests/test-rfifolock$(EXESUF)
check-unit-y += tests/test-throttle$(EXESUF)
gcov-files-test-aio-$(CONFIG_WIN32) = aio-win32.c
gcov-files-test-aio-$(CONFIG_POSIX) = aio-posix.c
@@ -490,7 +489,6 @@
tests/test-char$(EXESUF): tests/test-char.o qemu-char.o qemu-timer.o $(test-util-obj-y) $(qtest-obj-y) $(test-io-obj-y)
tests/test-coroutine$(EXESUF): tests/test-coroutine.o $(test-block-obj-y)
tests/test-aio$(EXESUF): tests/test-aio.o $(test-block-obj-y)
-tests/test-rfifolock$(EXESUF): tests/test-rfifolock.o $(test-util-obj-y)
tests/test-throttle$(EXESUF): tests/test-throttle.o $(test-block-obj-y)
tests/test-blockjob$(EXESUF): tests/test-blockjob.o $(test-block-obj-y) $(test-util-obj-y)
tests/test-blockjob-txn$(EXESUF): tests/test-blockjob-txn.o $(test-block-obj-y) $(test-util-obj-y)
diff --git a/tests/test-rfifolock.c b/tests/test-rfifolock.c
deleted file mode 100644
index 471a811..0000000
--- a/tests/test-rfifolock.c
+++ /dev/null
@@ -1,91 +0,0 @@
-/*
- * RFifoLock tests
- *
- * Copyright Red Hat, Inc. 2013
- *
- * Authors:
- * Stefan Hajnoczi <stefanha@redhat.com>
- *
- * This work is licensed under the terms of the GNU LGPL, version 2 or later.
- * See the COPYING.LIB file in the top-level directory.
- */
-
-#include "qemu/osdep.h"
-#include "qemu-common.h"
-#include "qemu/rfifolock.h"
-
-static void test_nesting(void)
-{
- RFifoLock lock;
-
- /* Trivial test, ensure the lock is recursive */
- rfifolock_init(&lock, NULL, NULL);
- rfifolock_lock(&lock);
- rfifolock_lock(&lock);
- rfifolock_lock(&lock);
- rfifolock_unlock(&lock);
- rfifolock_unlock(&lock);
- rfifolock_unlock(&lock);
- rfifolock_destroy(&lock);
-}
-
-typedef struct {
- RFifoLock lock;
- int fd[2];
-} CallbackTestData;
-
-static void rfifolock_cb(void *opaque)
-{
- CallbackTestData *data = opaque;
- int ret;
- char c = 0;
-
- ret = write(data->fd[1], &c, sizeof(c));
- g_assert(ret == 1);
-}
-
-static void *callback_thread(void *opaque)
-{
- CallbackTestData *data = opaque;
-
- /* The other thread holds the lock so the contention callback will be
- * invoked...
- */
- rfifolock_lock(&data->lock);
- rfifolock_unlock(&data->lock);
- return NULL;
-}
-
-static void test_callback(void)
-{
- CallbackTestData data;
- QemuThread thread;
- int ret;
- char c;
-
- rfifolock_init(&data.lock, rfifolock_cb, &data);
- ret = qemu_pipe(data.fd);
- g_assert(ret == 0);
-
- /* Hold lock but allow the callback to kick us by writing to the pipe */
- rfifolock_lock(&data.lock);
- qemu_thread_create(&thread, "callback_thread",
- callback_thread, &data, QEMU_THREAD_JOINABLE);
- ret = read(data.fd[0], &c, sizeof(c));
- g_assert(ret == 1);
- rfifolock_unlock(&data.lock);
- /* If we got here then the callback was invoked, as expected */
-
- qemu_thread_join(&thread);
- close(data.fd[0]);
- close(data.fd[1]);
- rfifolock_destroy(&data.lock);
-}
-
-int main(int argc, char **argv)
-{
- g_test_init(&argc, &argv, NULL);
- g_test_add_func("/nesting", test_nesting);
- g_test_add_func("/callback", test_callback);
- return g_test_run();
-}
diff --git a/util/Makefile.objs b/util/Makefile.objs
index 36c7dcc..ad0f9c7 100644
--- a/util/Makefile.objs
+++ b/util/Makefile.objs
@@ -25,7 +25,6 @@
util-obj-y += throttle.o
util-obj-y += getauxval.o
util-obj-y += readline.o
-util-obj-y += rfifolock.o
util-obj-y += rcu.o
util-obj-y += qemu-coroutine.o qemu-coroutine-lock.o qemu-coroutine-io.o
util-obj-y += qemu-coroutine-sleep.o
diff --git a/util/rfifolock.c b/util/rfifolock.c
deleted file mode 100644
index 084c2f0..0000000
--- a/util/rfifolock.c
+++ /dev/null
@@ -1,78 +0,0 @@
-/*
- * Recursive FIFO lock
- *
- * Copyright Red Hat, Inc. 2013
- *
- * Authors:
- * Stefan Hajnoczi <stefanha@redhat.com>
- *
- * This work is licensed under the terms of the GNU LGPL, version 2 or later.
- * See the COPYING.LIB file in the top-level directory.
- *
- */
-
-#include "qemu/osdep.h"
-#include "qemu/rfifolock.h"
-
-void rfifolock_init(RFifoLock *r, void (*cb)(void *), void *opaque)
-{
- qemu_mutex_init(&r->lock);
- r->head = 0;
- r->tail = 0;
- qemu_cond_init(&r->cond);
- r->nesting = 0;
- r->cb = cb;
- r->cb_opaque = opaque;
-}
-
-void rfifolock_destroy(RFifoLock *r)
-{
- qemu_cond_destroy(&r->cond);
- qemu_mutex_destroy(&r->lock);
-}
-
-/*
- * Theory of operation:
- *
- * In order to ensure FIFO ordering, implement a ticketlock. Threads acquiring
- * the lock enqueue themselves by incrementing the tail index. When the lock
- * is unlocked, the head is incremented and waiting threads are notified.
- *
- * Recursive locking does not take a ticket since the head is only incremented
- * when the outermost recursive caller unlocks.
- */
-void rfifolock_lock(RFifoLock *r)
-{
- qemu_mutex_lock(&r->lock);
-
- /* Take a ticket */
- unsigned int ticket = r->tail++;
-
- if (r->nesting > 0 && qemu_thread_is_self(&r->owner_thread)) {
- r->tail--; /* put ticket back, we're nesting */
- } else {
- while (ticket != r->head) {
- /* Invoke optional contention callback */
- if (r->cb) {
- r->cb(r->cb_opaque);
- }
- qemu_cond_wait(&r->cond, &r->lock);
- }
- qemu_thread_get_self(&r->owner_thread);
- }
-
- r->nesting++;
- qemu_mutex_unlock(&r->lock);
-}
-
-void rfifolock_unlock(RFifoLock *r)
-{
- qemu_mutex_lock(&r->lock);
- assert(r->nesting > 0);
- assert(qemu_thread_is_self(&r->owner_thread));
- if (--r->nesting == 0) {
- r->head++;
- qemu_cond_broadcast(&r->cond);
- }
- qemu_mutex_unlock(&r->lock);
-}
