Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1422826AbaGRSIU (ORCPT ); Fri, 18 Jul 2014 14:08:20 -0400 Received: from smtp.citrix.com ([66.165.176.89]:16605 "EHLO SMTP.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1422791AbaGRSIR (ORCPT ); Fri, 18 Jul 2014 14:08:17 -0400 X-IronPort-AV: E=Sophos;i="5.01,686,1400025600"; d="scan'208";a="153763629" From: Zoltan Kiss To: Wei Liu , Ian Campbell CC: Zoltan Kiss , , , Subject: [PATCH net 1/4 v2] xen-netback: Fix handling frag_list on grant op error path Date: Fri, 18 Jul 2014 19:08:02 +0100 Message-ID: <1405706885-16763-2-git-send-email-zoltan.kiss@citrix.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1405706885-16763-1-git-send-email-zoltan.kiss@citrix.com> References: <1405706885-16763-1-git-send-email-zoltan.kiss@citrix.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.80.2.133] X-DLP: MIA2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The error handling for skb's with frag_list was completely wrong, it caused double unmap attempts to happen if the error was on the first skb. Move it to the right place in the loop. Signed-off-by: Zoltan Kiss Reported-by: Armin Zentai Cc: netdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: xen-devel@lists.xenproject.org --- v2: grammar change in comment diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c index 1844a47..a773f20 100644 --- a/drivers/net/xen-netback/netback.c +++ b/drivers/net/xen-netback/netback.c @@ -1030,10 +1030,16 @@ static int xenvif_tx_check_gop(struct xenvif_queue *queue, { struct gnttab_map_grant_ref *gop_map = *gopp_map; u16 pending_idx = XENVIF_TX_CB(skb)->pending_idx; + /* This always points to the shinfo of the skb being checked, which + * could be either the first or the one on the frag_list + */ struct skb_shared_info *shinfo = skb_shinfo(skb); + /* If this is non-NULL, we are currently checking the frag_list skb, and + * this points to the shinfo of the first one + */ + struct skb_shared_info *first_shinfo = NULL; int nr_frags = shinfo->nr_frags; int i, err; - struct sk_buff *first_skb = NULL; /* Check status of header. */ err = (*gopp_copy)->status; @@ -1086,31 +1092,28 @@ check_frags: xenvif_idx_unmap(queue, pending_idx); } + /* And if we found the error while checking the frag_list, unmap + * the first skb's frags + */ + if (first_shinfo) { + for (j = 0; j < first_shinfo->nr_frags; j++) { + pending_idx = frag_get_pending_idx(&first_shinfo->frags[j]); + xenvif_idx_unmap(queue, pending_idx); + } + } + /* Remember the error: invalidate all subsequent fragments. */ err = newerr; } - if (skb_has_frag_list(skb)) { - first_skb = skb; - skb = shinfo->frag_list; - shinfo = skb_shinfo(skb); + if (skb_has_frag_list(skb) && !first_shinfo) { + first_shinfo = skb_shinfo(skb); + shinfo = skb_shinfo(skb_shinfo(skb)->frag_list); nr_frags = shinfo->nr_frags; goto check_frags; } - /* There was a mapping error in the frag_list skb. We have to unmap - * the first skb's frags - */ - if (first_skb && err) { - int j; - shinfo = skb_shinfo(first_skb); - for (j = 0; j < shinfo->nr_frags; j++) { - pending_idx = frag_get_pending_idx(&shinfo->frags[j]); - xenvif_idx_unmap(queue, pending_idx); - } - } - *gopp_map = gop_map; return err; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/