From: Stefan Bader <stefan.bader@canonical•com>
To: Ian Campbell <ian.campbell@citrix•com>
Cc: netdev@vger•kernel.org, xen-devel@lists•xen.org,
Eric Dumazet <edumazet@google•com>,
Konrad Rzeszutek Wilk <konrad@kernel•org>,
ANNIE LI <annie.li@oracle•com>,
Sander Eikelenboom <linux@eikelenboom•it>
Subject: Re: [PATCH] xen/netfront: handle compound page fragments on transmit
Date: Tue, 20 Nov 2012 14:30:54 +0100 [thread overview]
Message-ID: <50AB860E.3090106@canonical.com> (raw)
In-Reply-To: <1353411606-15940-1-git-send-email-ian.campbell@citrix.com>
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Aside from Jans comments about error handling, I tried below patch and it seems
to solve the problem with transfers out of the domU for me (though only shallow
testing done, otoh 5 times is more than getting stuck the first time).
-Stefan
On 20.11.2012 12:40, Ian Campbell wrote:
> An SKB paged fragment can consist of a compound page with order > 0.
> However the netchannel protocol deals only in PAGE_SIZE frames.
>
> Handle this in xennet_make_frags by iterating over the frames which
> make up the page.
>
> This is the netfront equivalent to 6a8ed462f16b for netback.
>
> Signed-off-by: Ian Campbell <ian.campbell@citrix•com>
> Cc: netdev@vger•kernel.org
> Cc: xen-devel@lists•xen.org
> Cc: Eric Dumazet <edumazet@google•com>
> Cc: Konrad Rzeszutek Wilk <konrad@kernel•org>
> Cc: ANNIE LI <annie.li@oracle•com>
> Cc: Sander Eikelenboom <linux@eikelenboom•it>
> Cc: Stefan Bader <stefan.bader@canonical•com>
Tested-by: Stefan Bader <stefan.bader@canonical•com>
> ---
> drivers/net/xen-netfront.c | 58 +++++++++++++++++++++++++++++++++----------
> 1 files changed, 44 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
> index caa0110..a12b99a 100644
> --- a/drivers/net/xen-netfront.c
> +++ b/drivers/net/xen-netfront.c
> @@ -452,24 +452,54 @@ static void xennet_make_frags(struct sk_buff *skb, struct net_device *dev,
> /* Grant backend access to each skb fragment page. */
> for (i = 0; i < frags; i++) {
> skb_frag_t *frag = skb_shinfo(skb)->frags + i;
> + struct page *page = skb_frag_page(frag);
> + unsigned long size = skb_frag_size(frag);
> + unsigned long offset = frag->page_offset;
>
> - tx->flags |= XEN_NETTXF_more_data;
> + /* Data must not cross a page boundary. */
> + BUG_ON(size + offset > PAGE_SIZE<<compound_order(page));
>
> - id = get_id_from_freelist(&np->tx_skb_freelist, np->tx_skbs);
> - np->tx_skbs[id].skb = skb_get(skb);
> - tx = RING_GET_REQUEST(&np->tx, prod++);
> - tx->id = id;
> - ref = gnttab_claim_grant_reference(&np->gref_tx_head);
> - BUG_ON((signed short)ref < 0);
> + /* Skip unused frames from start of page */
> + page += offset >> PAGE_SHIFT;
> + offset &= ~PAGE_MASK;
>
> - mfn = pfn_to_mfn(page_to_pfn(skb_frag_page(frag)));
> - gnttab_grant_foreign_access_ref(ref, np->xbdev->otherend_id,
> - mfn, GNTMAP_readonly);
> + while (size > 0) {
> + unsigned long bytes;
>
> - tx->gref = np->grant_tx_ref[id] = ref;
> - tx->offset = frag->page_offset;
> - tx->size = skb_frag_size(frag);
> - tx->flags = 0;
> + BUG_ON(offset >= PAGE_SIZE);
> +
> + bytes = PAGE_SIZE - offset;
> + if (bytes > size)
> + bytes = size;
> +
> + tx->flags |= XEN_NETTXF_more_data;
> +
> + id = get_id_from_freelist(&np->tx_skb_freelist, np->tx_skbs);
> + np->tx_skbs[id].skb = skb_get(skb);
> + tx = RING_GET_REQUEST(&np->tx, prod++);
> + tx->id = id;
> + ref = gnttab_claim_grant_reference(&np->gref_tx_head);
> + BUG_ON((signed short)ref < 0);
> +
> + mfn = pfn_to_mfn(page_to_pfn(page));
> + gnttab_grant_foreign_access_ref(ref, np->xbdev->otherend_id,
> + mfn, GNTMAP_readonly);
> +
> + tx->gref = np->grant_tx_ref[id] = ref;
> + tx->offset = offset;
> + tx->size = bytes;
> + tx->flags = 0;
> +
> + offset += bytes;
> + size -= bytes;
> +
> + /* Next frame */
> + if (offset == PAGE_SIZE && size) {
> + BUG_ON(!PageCompound(page));
> + page++;
> + offset = 0;
> + }
> + }
> }
>
> np->tx.req_prod_pvt = prod;
>
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next prev parent reply other threads:[~2012-11-20 13:31 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-09 13:47 compound skb frag pages appearing in start_xmit Ian Campbell
2012-10-09 13:54 ` Eric Dumazet
2012-10-09 14:01 ` Eric Dumazet
2012-10-09 14:23 ` Ian Campbell
2012-10-09 14:33 ` Eric Dumazet
2012-10-09 14:54 ` Ian Campbell
2012-10-09 14:17 ` Ian Campbell
2012-10-09 14:27 ` Eric Dumazet
2012-10-09 14:40 ` Ian Campbell
2012-10-09 14:51 ` Eric Dumazet
2012-10-10 10:13 ` [Xen-devel] " Ian Campbell
2012-10-10 12:24 ` Sander Eikelenboom
2012-10-10 12:29 ` [Xen-devel] " Ian Campbell
2012-10-10 13:31 ` Sander Eikelenboom
2012-10-10 13:09 ` Ian Campbell
2012-10-10 14:49 ` Sander Eikelenboom
2012-10-11 8:02 ` Ian Campbell
2012-10-11 10:00 ` Sander Eikelenboom
2012-10-11 10:05 ` Eric Dumazet
2012-10-11 10:14 ` Ian Campbell
2012-10-11 10:20 ` Sander Eikelenboom
2012-11-15 2:31 ` ANNIE LI
2012-11-19 15:43 ` Sander Eikelenboom
2012-11-20 8:30 ` [Xen-devel] " Stefan Bader
2012-11-20 9:21 ` Ian Campbell
2012-11-20 11:36 ` [Xen-devel] " Ian Campbell
2012-11-21 2:42 ` ANNIE LI
2012-11-20 11:40 ` [PATCH] xen/netfront: handle compound page fragments on transmit Ian Campbell
2012-11-20 12:28 ` [Xen-devel] " Jan Beulich
2012-11-20 13:35 ` Ian Campbell
2012-11-20 13:51 ` Jan Beulich
2012-11-20 14:14 ` Ian Campbell
2012-11-20 14:32 ` Jan Beulich
2012-11-20 15:06 ` Ian Campbell
2012-11-20 15:28 ` Eric Dumazet
2012-11-20 15:54 ` Ian Campbell
2012-11-20 15:44 ` Jan Beulich
2012-11-20 16:14 ` Eric Dumazet
2012-11-20 13:30 ` Stefan Bader [this message]
2012-11-20 13:45 ` Sander Eikelenboom
2012-11-20 14:45 ` Eric Dumazet
2012-11-20 15:05 ` Ian Campbell
2012-11-21 2:52 ` ANNIE LI
2012-11-21 11:09 ` Ian Campbell
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