Commit 7ee20fd8 authored Feb 02, 2021 by Juergen Gross Committed by Greg Kroah-Hartman Feb 23, 2021

xen/netback: avoid race in xenvif_rx_ring_slots_available()



[ Upstream commit ec7d8e7dd3a59528e305a18e93f1cb98f7faf83b ]

Since commit 23025393dbeb3b8b3 ("xen/netback: use lateeoi irq binding")
xenvif_rx_ring_slots_available() is no longer called only from the rx
queue kernel thread, so it needs to access the rx queue with the
associated queue held.

Reported-by: Igor Druzhinin <igor.druzhinin@citrix.com>
Fixes: 23025393dbeb3b8b3 ("xen/netback: use lateeoi irq binding")
Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Wei Liu <wl@xen.org>
Link: https://lore.kernel.org/r/20210202070938.7863-1-jgross@suse.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent dd07df94

drivers/net/xen-netback/rx.c

+8 −1

Original line number	Diff line number	Diff line
		@@ -38,10 +38,15 @@ static bool xenvif_rx_ring_slots_available(struct xenvif_queue *queue)
		RING_IDX prod, cons;
		struct sk_buff *skb;
		int needed;
		unsigned long flags;

		spin_lock_irqsave(&queue->rx_queue.lock, flags);

		skb = skb_peek(&queue->rx_queue);
		if (!skb)
		if (!skb) {
		spin_unlock_irqrestore(&queue->rx_queue.lock, flags);
		return false;
		}

		needed = DIV_ROUND_UP(skb->len, XEN_PAGE_SIZE);
		if (skb_is_gso(skb))
		@@ -49,6 +54,8 @@ static bool xenvif_rx_ring_slots_available(struct xenvif_queue *queue)
		if (skb->sw_hash)
		needed++;

		spin_unlock_irqrestore(&queue->rx_queue.lock, flags);

		do {
		prod = queue->rx.sring->req_prod;
		cons = queue->rx.req_cons;