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 <[email protected]>
Reported-by: Armin Zentai <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Signed-off-by: David S. Miller <[email protected]>
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 @@
{
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 @@
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;
}
