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bh=HOlY/UHLpbwih8IlglS/FB+polD3t6sdyX3kh+yI1Ao=; b=QtU8xHBYuPcqxiF9oJE/E3l9zMR3dH0r+L8BtEXD0TteUscsI77XY7djySqf4Qz+j0g4d+ RHtvmcgVhDYCuqF/DdvCuItJnM3+zluBRb+1pSNjd4AfnMOgLnNPvGYtL8sQZLxstJIsL4 heBvOyOESuSh5ftWp2d8DsKoDk0PomI= X-MC-Unique: 7bSGIw64N7-c18rE-N0_Fw-1 From: Kevin Wolf To: qemu-block@nongnu.org Cc: kwolf@redhat.com, stefanha@redhat.com, qemu-devel@nongnu.org Subject: [PULL 12/33] virtio-scsi: don't lock AioContext around virtio_queue_aio_attach_host_notifier() Date: Thu, 21 Dec 2023 22:23:17 +0100 Message-ID: <20231221212339.164439-13-kwolf@redhat.com> In-Reply-To: <20231221212339.164439-1-kwolf@redhat.com> References: <20231221212339.164439-1-kwolf@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.8 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.133.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.061, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1703194123751100002 Content-Type: text/plain; charset="utf-8" From: Stefan Hajnoczi virtio_queue_aio_attach_host_notifier() does not require the AioContext lock. Stop taking the lock and add an explicit smp_wmb() because we were relying on the implicit barrier in the AioContext lock before. Signed-off-by: Stefan Hajnoczi Reviewed-by: Eric Blake Reviewed-by: Kevin Wolf Message-ID: <20231204164259.1515217-3-stefanha@redhat.com> Signed-off-by: Kevin Wolf --- hw/scsi/virtio-scsi-dataplane.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) diff --git a/hw/scsi/virtio-scsi-dataplane.c b/hw/scsi/virtio-scsi-dataplan= e.c index 1e684beebe..135e23fe54 100644 --- a/hw/scsi/virtio-scsi-dataplane.c +++ b/hw/scsi/virtio-scsi-dataplane.c @@ -149,23 +149,17 @@ int virtio_scsi_dataplane_start(VirtIODevice *vdev) =20 memory_region_transaction_commit(); =20 - /* - * These fields are visible to the IOThread so we rely on implicit bar= riers - * in aio_context_acquire() on the write side and aio_notify_accept() = on - * the read side. - */ s->dataplane_starting =3D false; s->dataplane_started =3D true; + smp_wmb(); /* paired with aio_notify_accept() */ =20 if (s->bus.drain_count =3D=3D 0) { - aio_context_acquire(s->ctx); virtio_queue_aio_attach_host_notifier(vs->ctrl_vq, s->ctx); virtio_queue_aio_attach_host_notifier_no_poll(vs->event_vq, s->ctx= ); =20 for (i =3D 0; i < vs->conf.num_queues; i++) { virtio_queue_aio_attach_host_notifier(vs->cmd_vqs[i], s->ctx); } - aio_context_release(s->ctx); } return 0; =20 --=20 2.43.0