From: Björn Töpel Date: Thu, 22 Mar 2018 15:14:33 +0000 (+0100) Subject: i40e: tweak page counting for XDP_REDIRECT X-Git-Tag: v4.17-rc1~148^2~85^2~1 X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=8ce29c679a6ecefb88dc794260f4e91a284eed9a;p=linux.git i40e: tweak page counting for XDP_REDIRECT This commit tweaks the page counting for XDP_REDIRECT to function properly. XDP_REDIRECT support will be added in a future commit. The current page counting scheme assumes that the reference count cannot decrease until the received frame is sent to the upper layers of the networking stack. This assumption does not hold for the XDP_REDIRECT action, since a page (pointed out by xdp_buff) can have its reference count decreased via the xdp_do_redirect call. To work around that, we now start off by a large page count and then don't allow a refcount less than two. Signed-off-by: Björn Töpel Tested-by: Andrew Bowers Signed-off-by: Jeff Kirsher --- diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c b/drivers/net/ethernet/intel/i40e/i40e_txrx.c index 797bcdd3504e..9c338cef8315 100644 --- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c +++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c @@ -1588,9 +1588,8 @@ static bool i40e_alloc_mapped_page(struct i40e_ring *rx_ring, bi->dma = dma; bi->page = page; bi->page_offset = i40e_rx_offset(rx_ring); - - /* initialize pagecnt_bias to 1 representing we fully own page */ - bi->pagecnt_bias = 1; + page_ref_add(page, USHRT_MAX - 1); + bi->pagecnt_bias = USHRT_MAX; return true; } @@ -1956,8 +1955,8 @@ static bool i40e_can_reuse_rx_page(struct i40e_rx_buffer *rx_buffer) * the pagecnt_bias and page count so that we fully restock the * number of references the driver holds. */ - if (unlikely(!pagecnt_bias)) { - page_ref_add(page, USHRT_MAX); + if (unlikely(pagecnt_bias == 1)) { + page_ref_add(page, USHRT_MAX - 1); rx_buffer->pagecnt_bias = USHRT_MAX; }