Re: [Qemu-block] [PATCH 18/18] aio: convert from RFifoLock to QemuRecMutex

[Stefan Hajnoczi]

On Thu, Oct 13, 2016 at 07:34:22PM +0200, Paolo Bonzini wrote:
> It is simpler and a bit faster, and QEMU does not need the contention
> callbacks (and thus the fairness) anymore.
> 
> Reviewed-by: Fam Zheng 
> Signed-off-by: Paolo Bonzini 
> ---
>  async.c  |  8 ++---
>  include/block/aio.h  |  3 +-
>  include/qemu/rfifolock.h | 54 
>  tests/.gitignore |  1 -
>  tests/Makefile.include   |  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

Reviewed-by: Stefan Hajnoczi 


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[Qemu-block] [PATCH 18/18] aio: convert from RFifoLock to QemuRecMutex

[Paolo Bonzini]

It is simpler and a bit faster, and QEMU does not need the contention
callbacks (and thus the fairness) anymore.

Reviewed-by: Fam Zheng 
Signed-off-by: Paolo Bonzini 
---
 async.c  |  8 ++---
 include/block/aio.h  |  3 +-
 include/qemu/rfifolock.h | 54 
 tests/.gitignore |  1 -
 tests/Makefile.include   |  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 27db772..b2de360 100644
--- a/async.c
+++ b/async.c
@@ -284,7 +284,7 @@ aio_ctx_finalize(GSource *source)
 
 aio_set_event_notifier(ctx, >notifier, false, NULL);
 event_notifier_cleanup(>notifier);
-rfifolock_destroy(>lock);
+qemu_rec_mutex_destroy(>lock);
 qemu_mutex_destroy(>bh_lock);
 timerlistgroup_deinit(>tlg);
 }
@@ -372,7 +372,7 @@ AioContext *aio_context_new(Error **errp)
 #endif
 ctx->thread_pool = NULL;
 qemu_mutex_init(>bh_lock);
-rfifolock_init(>lock, NULL, NULL);
+qemu_rec_mutex_init(>lock);
 timerlistgroup_init(>tlg, aio_timerlist_notify, ctx);
 
 return ctx;
@@ -393,10 +393,10 @@ void aio_context_unref(AioContext *ctx)
 
 void aio_context_acquire(AioContext *ctx)
 {
-rfifolock_lock(>lock);
+qemu_rec_mutex_lock(>lock);
 }
 
 void aio_context_release(AioContext *ctx)
 {
-rfifolock_unlock(>lock);
+qemu_rec_mutex_unlock(>lock);
 }
diff --git a/include/block/aio.h b/include/block/aio.h
index 5714aba..758406a 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 @@ 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..000
--- a/include/qemu/rfifolock.h
+++ /dev/null
@@ -1,54 +0,0 @@
-/*
- * Recursive FIFO lock
- *
- * Copyright Red Hat, Inc. 2013
- *
- * Authors:
- *  Stefan Hajnoczi   
- *
- * 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 9f3d2ee..2cd897e 100644
--- a/tests/.gitignore
+++ b/tests/.gitignore
@@ -66,7 +66,6 @@ test-qmp-marshal.c
 test-qmp-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 a7c..26e7e90 100644
--- a/tests/Makefile.include
+++ b/tests/Makefile.include
@@ -43,7 +43,6 @@ 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