From 1b860da0404a76af8533099ffe0a965490939369 Mon Sep 17 00:00:00 2001 From: Zoltan Kiss Date: Fri, 18 Jul 2014 19:08:04 +0100 Subject: [PATCH] xen-netback: Fix releasing header slot on error path This patch makes this function aware that the first frag and the header might share the same ring slot. That could happen if the first slot is bigger than PKT_PROT_LEN. Due to this the error path might release that slot twice or never, depending on the error scenario. xenvif_idx_release is also removed from xenvif_idx_unmap, and called separately. 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 Signed-off-by: David S. Miller --- drivers/net/xen-netback/netback.c | 38 +++++++++++++++++++++++++++---- 1 file changed, 33 insertions(+), 5 deletions(-) diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c index 8cbf60d4689e..6fff911dc134 100644 --- a/drivers/net/xen-netback/netback.c +++ b/drivers/net/xen-netback/netback.c @@ -1039,6 +1039,8 @@ static int xenvif_tx_check_gop(struct xenvif_queue *queue, */ struct skb_shared_info *first_shinfo = NULL; int nr_frags = shinfo->nr_frags; + const bool sharedslot = nr_frags && + frag_get_pending_idx(&shinfo->frags[0]) == pending_idx; int i, err; /* Check status of header. */ @@ -1051,7 +1053,10 @@ static int xenvif_tx_check_gop(struct xenvif_queue *queue, (*gopp_copy)->status, pending_idx, (*gopp_copy)->source.u.ref); - xenvif_idx_release(queue, pending_idx, XEN_NETIF_RSP_ERROR); + /* The first frag might still have this slot mapped */ + if (!sharedslot) + xenvif_idx_release(queue, pending_idx, + XEN_NETIF_RSP_ERROR); } check_frags: @@ -1068,8 +1073,19 @@ check_frags: pending_idx, gop_map->handle); /* Had a previous error? Invalidate this fragment. */ - if (unlikely(err)) + if (unlikely(err)) { xenvif_idx_unmap(queue, pending_idx); + /* If the mapping of the first frag was OK, but + * the header's copy failed, and they are + * sharing a slot, send an error + */ + if (i == 0 && sharedslot) + xenvif_idx_release(queue, pending_idx, + XEN_NETIF_RSP_ERROR); + else + xenvif_idx_release(queue, pending_idx, + XEN_NETIF_RSP_OKAY); + } continue; } @@ -1081,15 +1097,27 @@ check_frags: gop_map->status, pending_idx, gop_map->ref); + xenvif_idx_release(queue, pending_idx, XEN_NETIF_RSP_ERROR); /* Not the first error? Preceding frags already invalidated. */ if (err) continue; - /* First error: invalidate preceding fragments. */ + + /* First error: if the header haven't shared a slot with the + * first frag, release it as well. + */ + if (!sharedslot) + xenvif_idx_release(queue, + XENVIF_TX_CB(skb)->pending_idx, + XEN_NETIF_RSP_OKAY); + + /* Invalidate preceding fragments of this skb. */ for (j = 0; j < i; j++) { pending_idx = frag_get_pending_idx(&shinfo->frags[j]); xenvif_idx_unmap(queue, pending_idx); + xenvif_idx_release(queue, pending_idx, + XEN_NETIF_RSP_OKAY); } /* And if we found the error while checking the frag_list, unmap @@ -1099,6 +1127,8 @@ check_frags: 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); + xenvif_idx_release(queue, pending_idx, + XEN_NETIF_RSP_OKAY); } } @@ -1834,8 +1864,6 @@ void xenvif_idx_unmap(struct xenvif_queue *queue, u16 pending_idx) tx_unmap_op.status); BUG(); } - - xenvif_idx_release(queue, pending_idx, XEN_NETIF_RSP_OKAY); } static inline int rx_work_todo(struct xenvif_queue *queue) -- 2.20.1