Blame SOURCES/0014-net-virtio-check-head-desc-with-correct-wrap-counter.patch

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From 82b43dd199d5492527b73002d4c3b009a98ca7a0 Mon Sep 17 00:00:00 2001
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From: Jens Freimann <jfreimann@redhat.com>
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Date: Fri, 11 Jan 2019 10:39:28 +0100
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Subject: [PATCH 14/18] net/virtio: check head desc with correct wrap counter
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[ upstream commit a4270ea4ff79b46280dd542f4ab3eb45f8c9685a ]
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In virtio_pq_send_command() we check for a used descriptor
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and wait in an idle loop until it becomes used. We can't use
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vq->used_wrap_counter here to check for the first descriptor
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we made available because the ring could have wrapped. Let's use
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the used_wrap_counter that matches the state of the head descriptor.
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Fixes: ec194c2f1895 ("net/virtio: support packed queue in send command")
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Signed-off-by: Jens Freimann <jfreimann@redhat.com>
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Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
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(cherry picked from commit a4270ea4ff79b46280dd542f4ab3eb45f8c9685a)
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Signed-off-by: Jens Freimann <jfreimann@redhat.com>
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---
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 drivers/net/virtio/virtio_ethdev.c | 11 ++++++-----
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 drivers/net/virtio/virtqueue.h     | 10 ++++++++--
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 2 files changed, 14 insertions(+), 7 deletions(-)
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diff --git a/drivers/net/virtio/virtio_ethdev.c b/drivers/net/virtio/virtio_ethdev.c
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index 53773445b..7bd38a292 100644
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--- a/drivers/net/virtio/virtio_ethdev.c
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+++ b/drivers/net/virtio/virtio_ethdev.c
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@@ -149,7 +149,7 @@ virtio_pq_send_command(struct virtnet_ctl *cvq, struct virtio_pmd_ctrl *ctrl,
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 	int head;
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 	struct vring_packed_desc *desc = vq->ring_packed.desc_packed;
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 	struct virtio_pmd_ctrl *result;
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-	int wrap_counter;
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+	bool avail_wrap_counter, used_wrap_counter;
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 	uint16_t flags;
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 	int sum = 0;
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 	int k;
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@@ -161,7 +161,8 @@ virtio_pq_send_command(struct virtnet_ctl *cvq, struct virtio_pmd_ctrl *ctrl,
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 	 * One RX packet for ACK.
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 	 */
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 	head = vq->vq_avail_idx;
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-	wrap_counter = vq->avail_wrap_counter;
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+	avail_wrap_counter = vq->avail_wrap_counter;
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+	used_wrap_counter = vq->used_wrap_counter;
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 	desc[head].flags = VRING_DESC_F_NEXT;
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 	desc[head].addr = cvq->virtio_net_hdr_mem;
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 	desc[head].len = sizeof(struct virtio_net_ctrl_hdr);
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@@ -199,8 +200,8 @@ virtio_pq_send_command(struct virtnet_ctl *cvq, struct virtio_pmd_ctrl *ctrl,
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 		 VRING_DESC_F_USED(!vq->avail_wrap_counter);
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 	desc[vq->vq_avail_idx].flags = flags;
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 	flags = VRING_DESC_F_NEXT;
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-	flags |= VRING_DESC_F_AVAIL(wrap_counter) |
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-		 VRING_DESC_F_USED(!wrap_counter);
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+	flags |= VRING_DESC_F_AVAIL(avail_wrap_counter) |
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+		 VRING_DESC_F_USED(!avail_wrap_counter);
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 	desc[head].flags = flags;
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 	rte_smp_wmb();
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@@ -216,7 +217,7 @@ virtio_pq_send_command(struct virtnet_ctl *cvq, struct virtio_pmd_ctrl *ctrl,
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 	do {
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 		rte_rmb();
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 		usleep(100);
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-	} while (!desc_is_used(&desc[head], vq));
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+	} while (!__desc_is_used(&desc[head], used_wrap_counter));
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 	/* now get used descriptors */
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 	while (desc_is_used(&desc[vq->vq_used_cons_idx], vq)) {
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diff --git a/drivers/net/virtio/virtqueue.h b/drivers/net/virtio/virtqueue.h
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index b142fd488..75f5782bc 100644
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--- a/drivers/net/virtio/virtqueue.h
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+++ b/drivers/net/virtio/virtqueue.h
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@@ -256,7 +256,7 @@ struct virtio_tx_region {
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 };
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 static inline int
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-desc_is_used(struct vring_packed_desc *desc, struct virtqueue *vq)
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+__desc_is_used(struct vring_packed_desc *desc, bool wrap_counter)
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 {
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 	uint16_t used, avail, flags;
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@@ -264,7 +264,13 @@ desc_is_used(struct vring_packed_desc *desc, struct virtqueue *vq)
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 	used = !!(flags & VRING_DESC_F_USED(1));
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 	avail = !!(flags & VRING_DESC_F_AVAIL(1));
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-	return avail == used && used == vq->used_wrap_counter;
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+	return avail == used && used == wrap_counter;
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+}
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+
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+static inline int
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+desc_is_used(struct vring_packed_desc *desc, struct virtqueue *vq)
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+{
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+	return __desc_is_used(desc, vq->used_wrap_counter);
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 }
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-- 
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2.21.0
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