From: Paolo Bonzini <pbonzini@redhat.com>
To: qemu-devel@nongnu.org
Cc: stefanha@redhat.com
Subject: [Qemu-devel] [PATCH 07/16] aio: convert from RFifoLock to QemuRecMutex
Date: Tue, 9 Feb 2016 12:46:05 +0100 [thread overview]
Message-ID: <1455018374-4706-8-git-send-email-pbonzini@redhat.com> (raw)
In-Reply-To: <1455018374-4706-1-git-send-email-pbonzini@redhat.com>
It is simpler and a bit faster, and QEMU does not need the contention
callbacks (and thus the fairness) anymore.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
async.c | 8 ++---
include/block/aio.h | 3 +-
include/qemu/rfifolock.h | 54 ----------------------------
tests/.gitignore | 1 -
tests/Makefile | 2 --
tests/test-rfifolock.c | 91 ------------------------------------------------
util/Makefile.objs | 1 -
util/rfifolock.c | 78 -----------------------------------------
8 files changed, 5 insertions(+), 233 deletions(-)
delete mode 100644 include/qemu/rfifolock.h
delete mode 100644 tests/test-rfifolock.c
delete mode 100644 util/rfifolock.c
diff --git a/async.c b/async.c
index 17a11fe..fc11b1c 100644
--- a/async.c
+++ b/async.c
@@ -254,7 +254,7 @@ aio_ctx_finalize(GSource *source)
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);
}
@@ -551,7 +551,7 @@ AioContext *aio_context_new(Error **errp)
event_notifier_dummy_cb);
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);
qemu_event_init(&ctx->sync_io_event, true);
@@ -577,7 +577,7 @@ void aio_context_acquire(AioContext *ctx)
if (ctx == qemu_get_aio_context()) {
assert(qemu_mutex_iothread_locked());
} else {
- rfifolock_lock(&ctx->lock);
+ qemu_rec_mutex_lock(&ctx->lock);
}
}
@@ -586,6 +586,6 @@ void aio_context_release(AioContext *ctx)
if (ctx == qemu_get_aio_context()) {
assert(qemu_mutex_iothread_locked());
} else {
- rfifolock_unlock(&ctx->lock);
+ qemu_rec_mutex_unlock(&ctx->lock);
}
}
diff --git a/include/block/aio.h b/include/block/aio.h
index 7223daf..3f055d2 100644
--- a/include/block/aio.h
+++ b/include/block/aio.h
@@ -19,7 +19,6 @@
#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;
@@ -52,7 +51,7 @@ struct AioContext {
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 787c95c..b3da3f1 100644
--- a/tests/.gitignore
+++ b/tests/.gitignore
@@ -51,7 +51,6 @@ test-qmp-introspect.[ch]
test-qmp-marshal.c
test-qmp-output-visitor
test-rcu-list
-test-rfifolock
test-string-input-visitor
test-string-output-visitor
test-thread-pool
diff --git a/tests/Makefile b/tests/Makefile
index 650e654..9da0fcf 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -39,7 +39,6 @@ check-unit-y += tests/test-visitor-serialization$(EXESUF)
check-unit-y += tests/test-iov$(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
@@ -403,7 +402,6 @@ tests/check-qom-interface$(EXESUF): tests/check-qom-interface.o $(test-qom-obj-y
tests/check-qom-proplist$(EXESUF): tests/check-qom-proplist.o $(test-qom-obj-y)
tests/test-coroutine$(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 $(test-block-obj-y)
tests/test-blockjob-txn$(EXESUF): tests/test-blockjob-txn.o $(test-block-obj-y) $(test-util-obj-y)
tests/test-thread-pool$(EXESUF): tests/test-thread-pool.o $(test-block-obj-y)
diff --git a/tests/test-rfifolock.c b/tests/test-rfifolock.c
deleted file mode 100644
index 0572ebb..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 <glib.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 a8a777e..c0223c6 100644
--- a/util/Makefile.objs
+++ b/util/Makefile.objs
@@ -23,7 +23,6 @@ util-obj-y += crc32c.o
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 c22f5fe..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);
-}
--
2.5.0
next prev parent reply other threads:[~2016-02-09 11:46 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-09 11:45 [Qemu-devel] [PATCH v3 00/16] aio: first part of aio_context_acquire/release pushdown Paolo Bonzini
2016-02-09 11:45 ` [Qemu-devel] [PATCH 01/16] aio: introduce aio_context_in_iothread Paolo Bonzini
2016-02-09 11:46 ` [Qemu-devel] [PATCH 02/16] aio: do not really acquire/release the main AIO context Paolo Bonzini
2016-02-09 11:46 ` [Qemu-devel] [PATCH 03/16] aio: introduce aio_poll_internal Paolo Bonzini
2016-02-09 11:46 ` [Qemu-devel] [PATCH 04/16] aio: only call aio_poll_internal from iothread Paolo Bonzini
2016-02-09 11:46 ` [Qemu-devel] [PATCH 05/16] iothread: release AioContext around aio_poll Paolo Bonzini
2016-02-09 11:46 ` [Qemu-devel] [PATCH 06/16] qemu-thread: introduce QemuRecMutex Paolo Bonzini
2016-02-09 11:46 ` Paolo Bonzini [this message]
2016-02-09 11:46 ` [Qemu-devel] [PATCH 08/16] aio: rename bh_lock to list_lock Paolo Bonzini
2016-02-09 11:46 ` [Qemu-devel] [PATCH 09/16] qemu-thread: introduce QemuLockCnt Paolo Bonzini
2016-02-09 11:46 ` [Qemu-devel] [PATCH 10/16] aio: make ctx->list_lock a QemuLockCnt, subsuming ctx->walking_bh Paolo Bonzini
2016-02-09 11:46 ` [Qemu-devel] [PATCH 11/16] qemu-thread: optimize QemuLockCnt with futexes on Linux Paolo Bonzini
2016-02-09 11:46 ` [Qemu-devel] [PATCH 12/16] aio: tweak walking in dispatch phase Paolo Bonzini
2016-02-09 11:46 ` [Qemu-devel] [PATCH 13/16] aio-posix: remove walking_handlers, protecting AioHandler list with list_lock Paolo Bonzini
2016-02-09 11:46 ` [Qemu-devel] [PATCH 14/16] aio-win32: " Paolo Bonzini
2016-02-09 11:46 ` [Qemu-devel] [PATCH 15/16] aio: document locking Paolo Bonzini
2016-02-09 11:46 ` [Qemu-devel] [PATCH 16/16] aio: push aio_context_acquire/release down to dispatching Paolo Bonzini
2016-02-09 14:01 ` [Qemu-devel] [PATCH v3 00/16] aio: first part of aio_context_acquire/release pushdown Stefan Hajnoczi
-- strict thread matches above, loose matches on Subject: below --
2016-02-08 16:14 [Qemu-devel] [PATCH v2 " Paolo Bonzini
2016-02-08 16:14 ` [Qemu-devel] [PATCH 07/16] aio: convert from RFifoLock to QemuRecMutex Paolo Bonzini
2016-01-15 15:12 [Qemu-devel] [PATCH 00/16] aio: first part of aio_context_acquire/release pushdown Paolo Bonzini
2016-01-15 15:12 ` [Qemu-devel] [PATCH 07/16] aio: convert from RFifoLock to QemuRecMutex Paolo Bonzini
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