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[83.52.55.163]) by smtp.gmail.com with ESMTPSA id f17sm3086742wmq.17.2021.08.26.10.27.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 26 Aug 2021 10:27:13 -0700 (PDT) From: =?utf-8?q?Philippe_Mathieu-Daud=C3=A9?= To: qemu-devel@nongnu.org Subject: [RFC PATCH 3/3] hw/virtio: Have virtqueue_get_avail_bytes() pass caches arg to callees Date: Thu, 26 Aug 2021 19:26:58 +0200 Message-Id: <20210826172658.2116840-4-philmd@redhat.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210826172658.2116840-1-philmd@redhat.com> References: <20210826172658.2116840-1-philmd@redhat.com> MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=philmd@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=170.10.133.124; envelope-from=philmd@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.742, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "Michael S. Tsirkin" , Jason Wang , Cornelia Huck , Stefan Hajnoczi , Paolo Bonzini , =?utf-8?q?Philippe_Mathieu-Daud=C3=A9?= Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" Both virtqueue_packed_get_avail_bytes() and virtqueue_split_get_avail_bytes() access the region cache, but their caller also does. Simplify by having virtqueue_get_avail_bytes calling both with RCU lock held, and passing the caches as argument. Signed-off-by: Philippe Mathieu-Daudé --- RFC because I'm not sure this is safe enough --- hw/virtio/virtio.c | 29 ++++++++++++----------------- 1 file changed, 12 insertions(+), 17 deletions(-) diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index 3a1f6c520cb..8237693a567 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -984,28 +984,23 @@ static int virtqueue_split_read_next_desc(VirtIODevice *vdev, VRingDesc *desc, return VIRTQUEUE_READ_DESC_MORE; } +/* Called within rcu_read_lock(). */ static void virtqueue_split_get_avail_bytes(VirtQueue *vq, unsigned int *in_bytes, unsigned int *out_bytes, - unsigned max_in_bytes, unsigned max_out_bytes) + unsigned max_in_bytes, unsigned max_out_bytes, + VRingMemoryRegionCaches *caches) { VirtIODevice *vdev = vq->vdev; unsigned int max, idx; unsigned int total_bufs, in_total, out_total; - VRingMemoryRegionCaches *caches; MemoryRegionCache indirect_desc_cache = MEMORY_REGION_CACHE_INVALID; int64_t len = 0; int rc; - RCU_READ_LOCK_GUARD(); - idx = vq->last_avail_idx; total_bufs = in_total = out_total = 0; max = vq->vring.num; - caches = vring_get_region_caches(vq); - if (!caches) { - goto err; - } while ((rc = virtqueue_num_heads(vq, idx)) > 0) { MemoryRegionCache *desc_cache = &caches->desc; @@ -1124,32 +1119,28 @@ static int virtqueue_packed_read_next_desc(VirtQueue *vq, return VIRTQUEUE_READ_DESC_MORE; } +/* Called within rcu_read_lock(). */ static void virtqueue_packed_get_avail_bytes(VirtQueue *vq, unsigned int *in_bytes, unsigned int *out_bytes, unsigned max_in_bytes, - unsigned max_out_bytes) + unsigned max_out_bytes, + VRingMemoryRegionCaches *caches) { VirtIODevice *vdev = vq->vdev; unsigned int max, idx; unsigned int total_bufs, in_total, out_total; MemoryRegionCache *desc_cache; - VRingMemoryRegionCaches *caches; MemoryRegionCache indirect_desc_cache = MEMORY_REGION_CACHE_INVALID; int64_t len = 0; VRingPackedDesc desc; bool wrap_counter; - RCU_READ_LOCK_GUARD(); idx = vq->last_avail_idx; wrap_counter = vq->last_avail_wrap_counter; total_bufs = in_total = out_total = 0; max = vq->vring.num; - caches = vring_get_region_caches(vq); - if (!caches) { - goto err; - } for (;;) { unsigned int num_bufs = total_bufs; @@ -1250,6 +1241,8 @@ void virtqueue_get_avail_bytes(VirtQueue *vq, unsigned int *in_bytes, uint16_t desc_size; VRingMemoryRegionCaches *caches; + RCU_READ_LOCK_GUARD(); + if (unlikely(!vq->vring.desc)) { goto err; } @@ -1268,10 +1261,12 @@ void virtqueue_get_avail_bytes(VirtQueue *vq, unsigned int *in_bytes, if (virtio_vdev_has_feature(vq->vdev, VIRTIO_F_RING_PACKED)) { virtqueue_packed_get_avail_bytes(vq, in_bytes, out_bytes, - max_in_bytes, max_out_bytes); + max_in_bytes, max_out_bytes, + caches); } else { virtqueue_split_get_avail_bytes(vq, in_bytes, out_bytes, - max_in_bytes, max_out_bytes); + max_in_bytes, max_out_bytes, + caches); } return;