From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:41051) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZNLo6-0005RS-CF for qemu-devel@nongnu.org; Thu, 06 Aug 2015 10:06:11 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZNLo1-0000cc-B1 for qemu-devel@nongnu.org; Thu, 06 Aug 2015 10:06:06 -0400 From: Paolo Bonzini Date: Thu, 6 Aug 2015 15:36:13 +0200 Message-Id: <1438868176-20364-16-git-send-email-pbonzini@redhat.com> In-Reply-To: <1438868176-20364-1-git-send-email-pbonzini@redhat.com> References: <1438868176-20364-1-git-send-email-pbonzini@redhat.com> Subject: [Qemu-devel] [PATCH 15/18] quorum: use atomics for rewrite_count List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: kwolf@redhat.com, famz@redhat.com, stefanha@redhat.com, qemu-block@nongnu.org This is simpler than taking and releasing the AioContext lock. Both quorum_rewrite_aio_cb and quorum_aio_finalize will be called without any lock taken. Signed-off-by: Paolo Bonzini --- block/quorum.c | 11 +++-------- 1 file changed, 3 insertions(+), 8 deletions(-) diff --git a/block/quorum.c b/block/quorum.c index 4e66221..0a42962 100644 --- a/block/quorum.c +++ b/block/quorum.c @@ -250,15 +250,10 @@ static void quorum_rewrite_aio_cb(void *opaque, int ret) { QuorumAIOCB *acb = opaque; - /* one less rewrite to do */ - acb->rewrite_count--; - /* wait until all rewrite callbacks have completed */ - if (acb->rewrite_count) { - return; + if (atomic_fetch_dec(&acb->rewrite_count) == 1) { + quorum_aio_finalize(acb); } - - quorum_aio_finalize(acb); } static BlockAIOCB *read_fifo_child(QuorumAIOCB *acb); @@ -361,7 +356,7 @@ static bool quorum_rewrite_bad_versions(BDRVQuorumState *s, QuorumAIOCB *acb, } /* quorum_rewrite_aio_cb will count down this to zero */ - acb->rewrite_count = count; + atomic_mb_set(&acb->rewrite_count, count); /* now fire the correcting rewrites */ QLIST_FOREACH(version, &acb->votes.vote_list, next) { -- 2.4.3