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[Qemu-devel] [PATCH] QEMUBH: make AioContext's bh re-entrant
From: |
Liu Ping Fan |
Subject: |
[Qemu-devel] [PATCH] QEMUBH: make AioContext's bh re-entrant |
Date: |
Fri, 14 Jun 2013 10:55:54 +0800 |
BH will be used outside big lock, so introduce lock to protect it.
Note that the lock only affects the writer and bh's callback does
not take this extra lock.
Signed-off-by: Liu Ping Fan <address@hidden>
---
async.c | 10 +++++++++-
include/block/aio.h | 2 ++
2 files changed, 11 insertions(+), 1 deletion(-)
diff --git a/async.c b/async.c
index 90fe906..b1dcead 100644
--- a/async.c
+++ b/async.c
@@ -47,8 +47,11 @@ QEMUBH *aio_bh_new(AioContext *ctx, QEMUBHFunc *cb, void
*opaque)
bh->ctx = ctx;
bh->cb = cb;
bh->opaque = opaque;
+ qemu_mutex_lock(&ctx->bh_lock);
bh->next = ctx->first_bh;
+ smp_wmb();
ctx->first_bh = bh;
+ qemu_mutex_unlock(&ctx->bh_lock);
return bh;
}
@@ -60,7 +63,9 @@ int aio_bh_poll(AioContext *ctx)
ctx->walking_bh++;
ret = 0;
- for (bh = ctx->first_bh; bh; bh = next) {
+ bh = ctx->first_bh;
+ smp_rmb();
+ for (; bh; bh = next) {
next = bh->next;
if (!bh->deleted && bh->scheduled) {
bh->scheduled = 0;
@@ -75,6 +80,7 @@ int aio_bh_poll(AioContext *ctx)
/* remove deleted bhs */
if (!ctx->walking_bh) {
+ qemu_mutex_lock(&ctx->bh_lock);
bhp = &ctx->first_bh;
while (*bhp) {
bh = *bhp;
@@ -85,6 +91,7 @@ int aio_bh_poll(AioContext *ctx)
bhp = &bh->next;
}
}
+ qemu_mutex_unlock(&ctx->bh_lock);
}
return ret;
@@ -211,6 +218,7 @@ AioContext *aio_context_new(void)
ctx = (AioContext *) g_source_new(&aio_source_funcs, sizeof(AioContext));
ctx->pollfds = g_array_new(FALSE, FALSE, sizeof(GPollFD));
ctx->thread_pool = NULL;
+ qemu_mutex_init(&ctx->bh_lock);
event_notifier_init(&ctx->notifier, false);
aio_set_event_notifier(ctx, &ctx->notifier,
(EventNotifierHandler *)
diff --git a/include/block/aio.h b/include/block/aio.h
index 1836793..a65d16f 100644
--- a/include/block/aio.h
+++ b/include/block/aio.h
@@ -17,6 +17,7 @@
#include "qemu-common.h"
#include "qemu/queue.h"
#include "qemu/event_notifier.h"
+#include "qemu/thread.h"
typedef struct BlockDriverAIOCB BlockDriverAIOCB;
typedef void BlockDriverCompletionFunc(void *opaque, int ret);
@@ -53,6 +54,7 @@ typedef struct AioContext {
*/
int walking_handlers;
+ QemuMutex bh_lock;
/* Anchor of the list of Bottom Halves belonging to the context */
struct QEMUBH *first_bh;
--
1.8.1.4
- [Qemu-devel] [PATCH] QEMUBH: make AioContext's bh re-entrant,
Liu Ping Fan <=