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[Qemu-block] [PATCH 15/18] quorum: use atomics for rewrite_count
From: |
Paolo Bonzini |
Subject: |
[Qemu-block] [PATCH 15/18] quorum: use atomics for rewrite_count |
Date: |
Thu, 6 Aug 2015 15:36:13 +0200 |
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 <address@hidden>
---
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
- [Qemu-block] [PATCH 03/18] qemu-thread: introduce QemuLockCnt, (continued)
- [Qemu-block] [PATCH 03/18] qemu-thread: introduce QemuLockCnt, Paolo Bonzini, 2015/08/06
- [Qemu-block] [PATCH 04/18] aio: make ctx->list_lock a QemuLockCnt, subsuming ctx->walking_bh, Paolo Bonzini, 2015/08/06
- [Qemu-block] [PATCH 06/18] aio-posix: remove walking_handlers, protecting AioHandler list with list_lock, Paolo Bonzini, 2015/08/06
- [Qemu-block] [PATCH 09/18] aio: push aio_context_acquire/release down to dispatching, Paolo Bonzini, 2015/08/06
- [Qemu-block] [PATCH 10/18] async: optimize aio_bh_poll, Paolo Bonzini, 2015/08/06
- [Qemu-block] [PATCH 16/18] quorum: split quorum_fifo_aio_cb from quorum_aio_cb, Paolo Bonzini, 2015/08/06
- [Qemu-block] [PATCH 05/18] aio: tweak walking in dispatch phase, Paolo Bonzini, 2015/08/06
- [Qemu-block] [PATCH 08/18] aio: document locking, Paolo Bonzini, 2015/08/06
- [Qemu-block] [PATCH 14/18] block: explicitly acquire aiocontext in timers that need it, Paolo Bonzini, 2015/08/06
- [Qemu-block] [PATCH 01/18] iothread: release iothread around aio_poll, Paolo Bonzini, 2015/08/06
- [Qemu-block] [PATCH 15/18] quorum: use atomics for rewrite_count,
Paolo Bonzini <=
- [Qemu-block] [PATCH 07/18] aio-win32: remove walking_handlers, protecting AioHandler list with list_lock, Paolo Bonzini, 2015/08/06
- [Qemu-block] [PATCH 18/18] aio: update locking documentation, Paolo Bonzini, 2015/08/06
- [Qemu-block] [PATCH 12/18] block: explicitly acquire aiocontext in callbacks that need it, Paolo Bonzini, 2015/08/06
- [Qemu-block] [PATCH 17/18] block: explicitly acquire aiocontext in aio callbacks that need it, Paolo Bonzini, 2015/08/06
- [Qemu-block] [PATCH 13/18] block: explicitly acquire aiocontext in bottom halves that need it, Paolo Bonzini, 2015/08/06
- [Qemu-block] [PATCH 11/18] qemu-timer: optimize timerlist_run_timers, Paolo Bonzini, 2015/08/06