From 1a998d3e6bc1e44f4c0bc7509bdedef8ed3845ec Mon Sep 17 00:00:00 2001 From: Zoltan Kiss Date: Fri, 18 Jul 2014 19:08:02 +0100 Subject: xen-netback: Fix handling frag_list on grant op error path 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 Signed-off-by: David S. Miller --- drivers/net/xen-netback/netback.c | 37 ++++++++++++++++++++----------------- 1 file changed, 20 insertions(+), 17 deletions(-) (limited to 'drivers/net/xen-netback') diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c index 1844a47636b6..a773f2016bad 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; } -- cgit v1.2.3 From b42cc6e421e7bf74e545483aa34b99d2a2ca6d3a Mon Sep 17 00:00:00 2001 From: Zoltan Kiss Date: Fri, 18 Jul 2014 19:08:03 +0100 Subject: xen-netback: Fix releasing frag_list skbs in error path When the grant operations failed, the skb is freed up eventually, and it tries to release the frags, if there is any. For the main skb nr_frags is set to 0 to avoid this, but on the frag_list it iterates through the frags array, and tries to call put_page on the page pointer which contains garbage at that time. 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 | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'drivers/net/xen-netback') diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c index a773f2016bad..8cbf60d4689e 100644 --- a/drivers/net/xen-netback/netback.c +++ b/drivers/net/xen-netback/netback.c @@ -1521,7 +1521,16 @@ static int xenvif_tx_submit(struct xenvif_queue *queue) /* Check the remap error code. */ if (unlikely(xenvif_tx_check_gop(queue, skb, &gop_map, &gop_copy))) { + /* If there was an error, xenvif_tx_check_gop is + * expected to release all the frags which were mapped, + * so kfree_skb shouldn't do it again + */ skb_shinfo(skb)->nr_frags = 0; + if (skb_has_frag_list(skb)) { + struct sk_buff *nskb = + skb_shinfo(skb)->frag_list; + skb_shinfo(nskb)->nr_frags = 0; + } kfree_skb(skb); continue; } -- cgit v1.2.3 From 1b860da0404a76af8533099ffe0a965490939369 Mon Sep 17 00:00:00 2001 From: Zoltan Kiss Date: Fri, 18 Jul 2014 19:08:04 +0100 Subject: 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(-) (limited to 'drivers/net/xen-netback') 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) -- cgit v1.2.3 From d8cfbfc4660054150ca1b7c501a8edc0771022f9 Mon Sep 17 00:00:00 2001 From: Zoltan Kiss Date: Fri, 18 Jul 2014 19:08:05 +0100 Subject: xen-netback: Fix pointer incrementation to avoid incorrect logging Due to this pointer is increased prematurely, the error log contains rubbish. 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 | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/net/xen-netback') diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c index 6fff911dc134..c65b636bcab9 100644 --- a/drivers/net/xen-netback/netback.c +++ b/drivers/net/xen-netback/netback.c @@ -1045,7 +1045,6 @@ static int xenvif_tx_check_gop(struct xenvif_queue *queue, /* Check status of header. */ err = (*gopp_copy)->status; - (*gopp_copy)++; if (unlikely(err)) { if (net_ratelimit()) netdev_dbg(queue->vif->dev, @@ -1058,6 +1057,7 @@ static int xenvif_tx_check_gop(struct xenvif_queue *queue, xenvif_idx_release(queue, pending_idx, XEN_NETIF_RSP_ERROR); } + (*gopp_copy)++; check_frags: for (i = 0; i < nr_frags; i++, gop_map++) { -- cgit v1.2.3