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Thu, 08 Jun 2017 11:57:03 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PULL v3 09/23] block: access wakeup with atomic ops X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: peter.maydell@linaro.org Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" From: Paolo Bonzini Reviewed-by: Stefan Hajnoczi Signed-off-by: Paolo Bonzini Message-Id: <20170605123908.18777-6-pbonzini@redhat.com> Signed-off-by: Fam Zheng --- 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 d76202b..4a59829 100644 --- a/block/io.c +++ b/block/io.c @@ -501,7 +501,8 @@ static void dummy_bh_cb(void *opaque) =20 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 848b2c0..18c87d2 100644 --- a/block/nfs.c +++ b/block/nfs.c @@ -730,7 +730,9 @@ nfs_get_allocated_file_size_cb(int ret, struct nfs_cont= ext *nfs, void *data, if (task->ret < 0) { error_report("NFS Error: %s", nfs_get_error(nfs)); } - task->complete =3D 1; + + /* Set task->complete before reading bs->wakeup. */ + atomic_mb_set(&task->complete, 1); bdrv_wakeup(task->bs); } =20 diff --git a/block/sheepdog.c b/block/sheepdog.c index a18315a..5ebf5d9 100644 --- a/block/sheepdog.c +++ b/block/sheepdog.c @@ -698,7 +698,8 @@ out: =20 srco->co =3D NULL; srco->ret =3D ret; - srco->finished =3D 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 9b355e9..a4f09df 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -402,7 +402,8 @@ void bdrv_drain_all(void); * block_job_defer_to_main_loop for how to do it). \ */ \ assert(!bs_->wakeup); \ - bs_->wakeup =3D true; \ + /* Set bs->wakeup before evaluating cond. */ \ + atomic_mb_set(&bs_->wakeup, true); \ while (busy_) { \ if ((cond)) { \ waited_ =3D busy_ =3D true; \ @@ -414,7 +415,7 @@ void bdrv_drain_all(void); waited_ |=3D busy_; \ } \ } \ - bs_->wakeup =3D false; \ + atomic_set(&bs_->wakeup, false); \ } \ waited_; }) =20 diff --git a/include/block/block_int.h b/include/block/block_int.h index 39be34a..cf544b7 100644 --- a/include/block/block_int.h +++ b/include/block/block_int.h @@ -604,8 +604,6 @@ struct BlockDriverState { /* Callback before write request is processed */ NotifierWithReturnList before_write_notifiers; =20 - bool wakeup; - /* Offset after the highest byte written to */ uint64_t wr_highest_offset; =20 @@ -636,6 +634,11 @@ struct BlockDriverState { unsigned int in_flight; unsigned int serialising_in_flight; =20 + /* 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; =20 --=20 2.9.4