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async: remove unnecessary inc/dec pairs 

Pull the increment/decrement pair out of aio_bh_poll and into the
callers.

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
Message-id: 20170213135235.12274-18-pbonzini@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
master
Paolo Bonzini 2017-02-13 14:52:34 +01:00 committed by Stefan Hajnoczi
parent a153bf52b3
commit bd451435c0
3 changed files with 13 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
util/aio-posix.c
View File

@ -425,9 +425,8 @@ static bool aio_dispatch_handlers(AioContext *ctx)
void aio_dispatch(AioContext *ctx)
{
aio_bh_poll(ctx);
qemu_lockcnt_inc(&ctx->list_lock);
aio_bh_poll(ctx);
aio_dispatch_handlers(ctx);
qemu_lockcnt_dec(&ctx->list_lock);
@ -679,16 +678,15 @@ bool aio_poll(AioContext *ctx, bool blocking)
}
npfd = 0;
qemu_lockcnt_dec(&ctx->list_lock);
progress |= aio_bh_poll(ctx);
if (ret > 0) {
qemu_lockcnt_inc(&ctx->list_lock);
progress |= aio_dispatch_handlers(ctx);
qemu_lockcnt_dec(&ctx->list_lock);
}
qemu_lockcnt_dec(&ctx->list_lock);
progress |= timerlistgroup_run_timers(&ctx->tlg);
return progress;

8
util/aio-win32.c
View File

@ -253,8 +253,6 @@ static bool aio_dispatch_handlers(AioContext *ctx, HANDLE event)
bool progress = false;
AioHandler *tmp;
qemu_lockcnt_inc(&ctx->list_lock);
/*
* We have to walk very carefully in case aio_set_fd_handler is
* called while we're walking.
@ -305,14 +303,15 @@ static bool aio_dispatch_handlers(AioContext *ctx, HANDLE event)
}
}
qemu_lockcnt_dec(&ctx->list_lock);
return progress;
}
void aio_dispatch(AioContext *ctx)
{
qemu_lockcnt_inc(&ctx->list_lock);
aio_bh_poll(ctx);
aio_dispatch_handlers(ctx, INVALID_HANDLE_VALUE);
qemu_lockcnt_dec(&ctx->list_lock);
timerlistgroup_run_timers(&ctx->tlg);
}
@ -349,7 +348,6 @@ bool aio_poll(AioContext *ctx, bool blocking)
}
}
qemu_lockcnt_dec(&ctx->list_lock);
first = true;
/* ctx->notifier is always registered. */
@ -392,6 +390,8 @@ bool aio_poll(AioContext *ctx, bool blocking)
progress |= aio_dispatch_handlers(ctx, event);
} while (count > 0);
qemu_lockcnt_dec(&ctx->list_lock);
progress |= timerlistgroup_run_timers(&ctx->tlg);
return progress;
}

12
util/async.c
View File

@ -90,15 +90,16 @@ void aio_bh_call(QEMUBH *bh)
bh->cb(bh->opaque);
}
/* Multiple occurrences of aio_bh_poll cannot be called concurrently */
/* Multiple occurrences of aio_bh_poll cannot be called concurrently.
* The count in ctx->list_lock is incremented before the call, and is
* not affected by the call.
*/
int aio_bh_poll(AioContext *ctx)
{
QEMUBH *bh, **bhp, *next;
int ret;
bool deleted = false;
qemu_lockcnt_inc(&ctx->list_lock);
ret = 0;
for (bh = atomic_rcu_read(&ctx->first_bh); bh; bh = next) {
next = atomic_rcu_read(&bh->next);
@ -123,11 +124,10 @@ int aio_bh_poll(AioContext *ctx)
/* remove deleted bhs */
if (!deleted) {
qemu_lockcnt_dec(&ctx->list_lock);
return ret;
}
if (qemu_lockcnt_dec_and_lock(&ctx->list_lock)) {
if (qemu_lockcnt_dec_if_lock(&ctx->list_lock)) {
bhp = &ctx->first_bh;
while (*bhp) {
bh = *bhp;
@ -138,7 +138,7 @@ int aio_bh_poll(AioContext *ctx)
bhp = &bh->next;
}
}
qemu_lockcnt_unlock(&ctx->list_lock);
qemu_lockcnt_inc_and_unlock(&ctx->list_lock);
}
return ret;
}