From 961045004b774aae7a244fa0435f8a6a2495c234 Mon Sep 17 00:00:00 2001 From: Yunsheng Lin Date: Fri, 18 Jun 2021 20:09:45 +0800 Subject: [PATCH] net: hns3: fix reuse conflict of the rx page In the current rx page reuse handling process, the rx page buffer may have conflict between driver and stack in high-pressure scenario. To fix this problem, we need to check whether the page is only owned by driver at the begin and at the end of a page to make sure there is no reuse conflict between driver and stack when desc_cb->page_offset is rollbacked to zero or increased. Fixes: fa7711b888f2 ("net: hns3: optimize the rx page reuse handling process") Signed-off-by: Yunsheng Lin Signed-off-by: Guangbin Huang Signed-off-by: David S. Miller --- drivers/net/ethernet/hisilicon/hns3/hns3_enet.c | 26 ++++++++++++++++++------- 1 file changed, 19 insertions(+), 7 deletions(-) diff --git a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c index 51bbf5f..cdb5f14 100644 --- a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c +++ b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c @@ -3537,21 +3537,33 @@ static void hns3_nic_reuse_page(struct sk_buff *skb, int i, int size = le16_to_cpu(desc->rx.size); u32 truesize = hns3_buf_size(ring); u32 frag_size = size - pull_len; + bool reused; /* Avoid re-using remote or pfmem page */ if (unlikely(!dev_page_is_reusable(desc_cb->priv))) goto out; - /* Stack is not using and current page_offset is non-zero, we can - * reuse from the zero offset. + reused = hns3_can_reuse_page(desc_cb); + + /* Rx page can be reused when: + * 1. Rx page is only owned by the driver when page_offset + * is zero, which means 0 @ truesize will be used by + * stack after skb_add_rx_frag() is called, and the rest + * of rx page can be reused by driver. + * Or + * 2. Rx page is only owned by the driver when page_offset + * is non-zero, which means page_offset @ truesize will + * be used by stack after skb_add_rx_frag() is called, + * and 0 @ truesize can be reused by driver. */ - if (desc_cb->page_offset && hns3_can_reuse_page(desc_cb)) { - desc_cb->page_offset = 0; - desc_cb->reuse_flag = 1; - } else if (desc_cb->page_offset + truesize * 2 <= - hns3_page_size(ring)) { + if ((!desc_cb->page_offset && reused) || + ((desc_cb->page_offset + truesize + truesize) <= + hns3_page_size(ring) && desc_cb->page_offset)) { desc_cb->page_offset += truesize; desc_cb->reuse_flag = 1; + } else if (desc_cb->page_offset && reused) { + desc_cb->page_offset = 0; + desc_cb->reuse_flag = 1; } else if (frag_size <= ring->rx_copybreak) { void *frag = napi_alloc_frag(frag_size); -- 2.7.4