Re: [PATCH RFC v1 03/15] bnxt: add XDP frame size to driver
From: Andy Gospodarek <andy@greyhouse.net>
Date: 2020-03-20 19:22:10
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bpf
On Tue, Mar 17, 2020 at 06:29:22PM +0100, Jesper Dangaard Brouer wrote:
quoted hunk ↗ jump to hunk
This driver uses full PAGE_SIZE pages when XDP is enabled. Cc: Michael Chan <michael.chan@broadcom.com> Cc: Andy Gospodarek <redacted> Signed-off-by: Jesper Dangaard Brouer <redacted> --- drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c | 1 + 1 file changed, 1 insertion(+)diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c b/drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c index c6f6f2033880..5e3b4a3b69ea 100644 --- a/drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c +++ b/drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c@@ -138,6 +138,7 @@ bool bnxt_rx_xdp(struct bnxt *bp, struct bnxt_rx_ring_info *rxr, u16 cons, xdp_set_data_meta_invalid(&xdp); xdp.data_end = *data_ptr + *len; xdp.rxq = &rxr->xdp_rxq; + xdp.frame_sz = PAGE_SIZE; /* BNXT_RX_PAGE_MODE(bp) when XDP enabled */
So if we want this to be the true size that the packet inside the the DMA buffer could grow to, I _think_ this would need to be: xdp.frame_sz = PAGE_SIZE - XDP_PACKET_HEADROOM; but I also noted that in patch 8 of the series that there is a check against data_end - data_hard_start, so functionally your original patch appears to be correct. If the intent was just to capture the size of the [DMA] buffer available for the datagram, maybe calling this new field 'buf_sz' or similar would be nice as it does not convey anything about the on-wire size like 'frame_sz' does.
orig_data = xdp.data; rcu_read_lock();