From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42137) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1d8pIR-0001Vh-8W for qemu-devel@nongnu.org; Thu, 11 May 2017 10:42:28 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1d8pIO-0004Ah-JQ for qemu-devel@nongnu.org; Thu, 11 May 2017 10:42:27 -0400 From: Paolo Bonzini Date: Thu, 11 May 2017 16:41:55 +0200 Message-Id: <20170511144208.24075-6-pbonzini@redhat.com> In-Reply-To: <20170511144208.24075-1-pbonzini@redhat.com> References: <20170511144208.24075-1-pbonzini@redhat.com> Subject: [Qemu-devel] [PATCH 05/18] block: access wakeup with atomic ops List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: famz@redhat.com, stefanha@redhat.com, qemu-block@nongnu.org Signed-off-by: Paolo Bonzini --- v1->v2: add comment [Fam] block/io.c | 3 ++- block/nfs.c | 4 +++- block/sheepdog.c | 3 ++- include/block/block.h | 5 +++-- include/block/block_int.h | 7 +++++-- 5 files changed, 15 insertions(+), 7 deletions(-) diff --git a/block/io.c b/block/io.c index 28d2de6d93..dcb2b72f91 100644 --- a/block/io.c +++ b/block/io.c @@ -501,7 +501,8 @@ static void dummy_bh_cb(void *opaque) void bdrv_wakeup(BlockDriverState *bs) { - if (bs->wakeup) { + /* The barrier (or an atomic op) is in the caller. */ + if (atomic_read(&bs->wakeup)) { aio_bh_schedule_oneshot(qemu_get_aio_context(), dummy_bh_cb, NULL); } } diff --git a/block/nfs.c b/block/nfs.c index 6541dec1fc..ec75c6c4ca 100644 --- a/block/nfs.c +++ b/block/nfs.c @@ -736,7 +736,9 @@ nfs_get_allocated_file_size_cb(int ret, struct nfs_context *nfs, void *data, if (task->ret < 0) { error_report("NFS Error: %s", nfs_get_error(nfs)); } - task->complete = 1; + + /* Set task->complete before reading bs->wakeup. */ + atomic_mb_set(&task->complete, 1); bdrv_wakeup(task->bs); } diff --git a/block/sheepdog.c b/block/sheepdog.c index b2a5998188..dad998a2c7 100644 --- a/block/sheepdog.c +++ b/block/sheepdog.c @@ -704,7 +704,8 @@ out: srco->co = NULL; srco->ret = ret; - srco->finished = true; + /* Set srco->finished before reading bs->wakeup. */ + atomic_mb_set(&srco->finished, true); if (srco->bs) { bdrv_wakeup(srco->bs); } diff --git a/include/block/block.h b/include/block/block.h index 144df0ddfb..bad445acd8 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -398,7 +398,8 @@ void bdrv_drain_all(void); * block_job_defer_to_main_loop for how to do it). \ */ \ assert(!bs_->wakeup); \ - bs_->wakeup = true; \ + /* Set bs->wakeup before evaluating cond. */ \ + atomic_mb_set(&bs_->wakeup, true); \ while (busy_) { \ if ((cond)) { \ waited_ = busy_ = true; \ @@ -410,7 +411,7 @@ void bdrv_drain_all(void); waited_ |= busy_; \ } \ } \ - bs_->wakeup = false; \ + atomic_set(&bs_->wakeup, false); \ } \ waited_; }) diff --git a/include/block/block_int.h b/include/block/block_int.h index 8db83c2b2d..0799098060 100644 --- a/include/block/block_int.h +++ b/include/block/block_int.h @@ -590,8 +590,6 @@ struct BlockDriverState { /* Callback before write request is processed */ NotifierWithReturnList before_write_notifiers; - bool wakeup; - /* Offset after the highest byte written to */ uint64_t wr_highest_offset; @@ -622,6 +620,11 @@ struct BlockDriverState { unsigned int in_flight; unsigned int serialising_in_flight; + /* Internal to BDRV_POLL_WHILE and bdrv_wakeup. Accessed with atomic + * ops. + */ + bool wakeup; + /* do we need to tell the quest if we have a volatile write cache? */ int enable_write_cache; -- 2.12.2