Wei Liu
2013-May-02 10:43 UTC
[PATCH net-next V2 3/3] xen-netback: better names for thresholds
This patch only changes some names to avoid confusion.
In this patch we have:
MAX_SKB_SLOTS_DEFAULT -> FATAL_SKB_SLOTS_DEFAULT
max_skb_slots -> fatal_skb_slots
#define XEN_NETBK_LEGACY_SLOTS_MAX XEN_NETIF_NR_SLOTS_MIN
The fatal_skb_slots is the threshold to determine whether a packet is
malicious.
XEN_NETBK_LEGACY_SLOTS_MAX is the maximum slots a valid packet can have at
this point. It is defined to be XEN_NETIF_NR_SLOTS_MIN because that''s
guaranteed to be supported by all backends.
Suggested-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
---
drivers/net/xen-netback/netback.c | 49 ++++++++++++++++++++++---------------
1 file changed, 29 insertions(+), 20 deletions(-)
diff --git a/drivers/net/xen-netback/netback.c
b/drivers/net/xen-netback/netback.c
index ce8109f..37984e6 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -51,9 +51,17 @@
* This is the maximum slots a skb can have. If a guest sends a skb
* which exceeds this limit it is considered malicious.
*/
-#define MAX_SKB_SLOTS_DEFAULT 20
-static unsigned int max_skb_slots = MAX_SKB_SLOTS_DEFAULT;
-module_param(max_skb_slots, uint, 0444);
+#define FATAL_SKB_SLOTS_DEFAULT 20
+static unsigned int fatal_skb_slots = FATAL_SKB_SLOTS_DEFAULT;
+module_param(fatal_skb_slots, uint, 0444);
+
+/*
+ * To avoid confusion, we define XEN_NETBK_LEGACY_SLOTS_MAX indicating
+ * the maximum slots a valid packet can use. Now this value is defined
+ * to be XEN_NETIF_NR_SLOTS_MIN, which is supposed to be supported by
+ * all backend.
+ */
+#define XEN_NETBK_LEGACY_SLOTS_MAX XEN_NETIF_NR_SLOTS_MIN
typedef unsigned int pending_ring_idx_t;
#define INVALID_PENDING_RING_IDX (~0U)
@@ -953,25 +961,26 @@ static int netbk_count_requests(struct xenvif *vif,
/* This guest is really using too many slots and
* considered malicious.
*/
- if (unlikely(slots >= max_skb_slots)) {
+ if (unlikely(slots >= fatal_skb_slots)) {
netdev_err(vif->dev,
"Malicious frontend using %d slots, threshold %u\n",
- slots, max_skb_slots);
+ slots, fatal_skb_slots);
netbk_fatal_tx_err(vif);
return -E2BIG;
}
/* Xen network protocol had implicit dependency on
- * MAX_SKB_FRAGS. XEN_NETIF_NR_SLOTS_MIN is set to the
- * historical MAX_SKB_FRAGS value 18 to honor the same
- * behavior as before. Any packet using more than 18
- * slots but less than max_skb_slots slots is dropped
+ * MAX_SKB_FRAGS. XEN_NETBK_LEGACY_SLOTS_MAX is set to
+ * the historical MAX_SKB_FRAGS value 18 to honor the
+ * same behavior as before. Any packet using more than
+ * 18 slots but less than fatal_skb_slots slots is
+ * dropped
*/
- if (!drop_err && slots >= XEN_NETIF_NR_SLOTS_MIN) {
+ if (!drop_err && slots >= XEN_NETBK_LEGACY_SLOTS_MAX) {
if (net_ratelimit())
netdev_dbg(vif->dev,
"Too many slots (%d) exceeding limit (%d), dropping
packet\n",
- slots, XEN_NETIF_NR_SLOTS_MIN);
+ slots, XEN_NETBK_LEGACY_SLOTS_MAX);
drop_err = -E2BIG;
}
@@ -1053,7 +1062,7 @@ static struct gnttab_copy *xen_netbk_get_requests(struct
xen_netbk *netbk,
struct pending_tx_info *first = NULL;
/* At this point shinfo->nr_frags is in fact the number of
- * slots, which can be as large as XEN_NETIF_NR_SLOTS_MIN.
+ * slots, which can be as large as XEN_NETBK_LEGACY_SLOTS_MAX.
*/
nr_slots = shinfo->nr_frags;
@@ -1415,12 +1424,12 @@ static unsigned xen_netbk_tx_build_gops(struct xen_netbk
*netbk)
struct sk_buff *skb;
int ret;
- while ((nr_pending_reqs(netbk) + XEN_NETIF_NR_SLOTS_MIN
+ while ((nr_pending_reqs(netbk) + XEN_NETBK_LEGACY_SLOTS_MAX
< MAX_PENDING_REQS) &&
!list_empty(&netbk->net_schedule_list)) {
struct xenvif *vif;
struct xen_netif_tx_request txreq;
- struct xen_netif_tx_request txfrags[XEN_NETIF_NR_SLOTS_MIN];
+ struct xen_netif_tx_request txfrags[XEN_NETBK_LEGACY_SLOTS_MAX];
struct page *page;
struct xen_netif_extra_info extras[XEN_NETIF_EXTRA_TYPE_MAX-1];
u16 pending_idx;
@@ -1508,7 +1517,7 @@ static unsigned xen_netbk_tx_build_gops(struct xen_netbk
*netbk)
pending_idx = netbk->pending_ring[index];
data_len = (txreq.size > PKT_PROT_LEN &&
- ret < XEN_NETIF_NR_SLOTS_MIN) ?
+ ret < XEN_NETBK_LEGACY_SLOTS_MAX) ?
PKT_PROT_LEN : txreq.size;
skb = alloc_skb(data_len + NET_SKB_PAD + NET_IP_ALIGN,
@@ -1787,7 +1796,7 @@ static inline int rx_work_todo(struct xen_netbk *netbk)
static inline int tx_work_todo(struct xen_netbk *netbk)
{
- if ((nr_pending_reqs(netbk) + XEN_NETIF_NR_SLOTS_MIN
+ if ((nr_pending_reqs(netbk) + XEN_NETBK_LEGACY_SLOTS_MAX
< MAX_PENDING_REQS) &&
!list_empty(&netbk->net_schedule_list))
return 1;
@@ -1872,11 +1881,11 @@ static int __init netback_init(void)
if (!xen_domain())
return -ENODEV;
- if (max_skb_slots < XEN_NETIF_NR_SLOTS_MIN) {
+ if (fatal_skb_slots < XEN_NETBK_LEGACY_SLOTS_MAX) {
printk(KERN_INFO
- "xen-netback: max_skb_slots too small (%d), bump it to
XEN_NETIF_NR_SLOTS_MIN (%d)\n",
- max_skb_slots, XEN_NETIF_NR_SLOTS_MIN);
- max_skb_slots = XEN_NETIF_NR_SLOTS_MIN;
+ "xen-netback: fatal_skb_slots too small (%d), bump it to
XEN_NETBK_LEGACY_SLOTS_MAX (%d)\n",
+ fatal_skb_slots, XEN_NETBK_LEGACY_SLOTS_MAX);
+ fatal_skb_slots = XEN_NETBK_LEGACY_SLOTS_MAX;
}
xen_netbk_group_nr = num_online_cpus();
--
1.7.10.4