net: Implement read-only protection and COW'ing of metrics.

[mirror_ubuntu-artful-kernel.git] / include / net / dst.h

diff --git a/include/net/dst.h b/include/net/dst.h
index be5a0d4c491d98eb1c2123364a137c5c954a4152..94a8c234ea2a24488443d6f1f4d664da839e9ad4 100644 (file)
--- a/include/net/dst.h
+++ b/include/net/dst.h
@@ -40,24 +40,10 @@ struct dst_entry {
        struct rcu_head         rcu_head;
        struct dst_entry        *child;
        struct net_device       *dev;
-       short                   error;
-       short                   obsolete;
-       int                     flags;
-#define DST_HOST               0x0001
-#define DST_NOXFRM             0x0002
-#define DST_NOPOLICY           0x0004
-#define DST_NOHASH             0x0008
-#define DST_NOCACHE            0x0010
+       struct  dst_ops         *ops;
+       unsigned long           _metrics;
        unsigned long           expires;
-
-       unsigned short          header_len;     /* more space at head required */
-       unsigned short          trailer_len;    /* space to reserve at tail */
-
-       unsigned int            rate_tokens;
-       unsigned long           rate_last;      /* rate limiting for ICMP */
-
        struct dst_entry        *path;
-
        struct neighbour        *neighbour;
        struct hh_cache         *hh;
 #ifdef CONFIG_XFRM
@@ -68,17 +54,16 @@ struct dst_entry {
        int                     (*input)(struct sk_buff*);
        int                     (*output)(struct sk_buff*);
 
-       struct  dst_ops         *ops;
-
-       u32                     _metrics[RTAX_MAX];
-
+       short                   error;
+       short                   obsolete;
+       unsigned short          header_len;     /* more space at head required */
+       unsigned short          trailer_len;    /* space to reserve at tail */
 #ifdef CONFIG_IP_ROUTE_CLASSID
        __u32                   tclassid;
 #else
        __u32                   __pad2;
 #endif
 
-
        /*
         * Align __refcnt to a 64 bytes alignment
         * (L1_CACHE_SIZE would be too much)
@@ -93,6 +78,14 @@ struct dst_entry {
        atomic_t                __refcnt;       /* client references    */
        int                     __use;
        unsigned long           lastuse;
+       unsigned long           rate_last;      /* rate limiting for ICMP */
+       unsigned int            rate_tokens;
+       int                     flags;
+#define DST_HOST               0x0001
+#define DST_NOXFRM             0x0002
+#define DST_NOPOLICY           0x0004
+#define DST_NOHASH             0x0008
+#define DST_NOCACHE            0x0010
        union {
                struct dst_entry        *next;
                struct rtable __rcu     *rt_next;
@@ -103,10 +96,69 @@ struct dst_entry {
 
 #ifdef __KERNEL__
 
+extern u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old);
+
+#define DST_METRICS_READ_ONLY  0x1UL
+#define __DST_METRICS_PTR(Y)   \
+       ((u32 *)((Y) & ~DST_METRICS_READ_ONLY))
+#define DST_METRICS_PTR(X)     __DST_METRICS_PTR((X)->_metrics)
+
+static inline bool dst_metrics_read_only(const struct dst_entry *dst)
+{
+       return dst->_metrics & DST_METRICS_READ_ONLY;
+}
+
+extern void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old);
+
+static inline void dst_destroy_metrics_generic(struct dst_entry *dst)
+{
+       unsigned long val = dst->_metrics;
+       if (!(val & DST_METRICS_READ_ONLY))
+               __dst_destroy_metrics_generic(dst, val);
+}
+
+static inline u32 *dst_metrics_write_ptr(struct dst_entry *dst)
+{
+       unsigned long p = dst->_metrics;
+
+       if (p & DST_METRICS_READ_ONLY)
+               return dst->ops->cow_metrics(dst, p);
+       return __DST_METRICS_PTR(p);
+}
+
+/* This may only be invoked before the entry has reached global
+ * visibility.
+ */
+static inline void dst_init_metrics(struct dst_entry *dst,
+                                   const u32 *src_metrics,
+                                   bool read_only)
+{
+       dst->_metrics = ((unsigned long) src_metrics) |
+               (read_only ? DST_METRICS_READ_ONLY : 0);
+}
+
+static inline void dst_copy_metrics(struct dst_entry *dest, const struct dst_entry *src)
+{
+       u32 *dst_metrics = dst_metrics_write_ptr(dest);
+
+       if (dst_metrics) {
+               u32 *src_metrics = DST_METRICS_PTR(src);
+
+               memcpy(dst_metrics, src_metrics, RTAX_MAX * sizeof(u32));
+       }
+}
+
+static inline u32 *dst_metrics_ptr(struct dst_entry *dst)
+{
+       return DST_METRICS_PTR(dst);
+}
+
 static inline u32
 dst_metric_raw(const struct dst_entry *dst, const int metric)
 {
-       return dst->_metrics[metric-1];
+       u32 *p = DST_METRICS_PTR(dst);
+
+       return p[metric-1];
 }
 
 static inline u32
@@ -131,22 +183,10 @@ dst_metric_advmss(const struct dst_entry *dst)
 
 static inline void dst_metric_set(struct dst_entry *dst, int metric, u32 val)
 {
-       dst->_metrics[metric-1] = val;
-}
-
-static inline void dst_import_metrics(struct dst_entry *dst, const u32 *src_metrics)
-{
-       memcpy(dst->_metrics, src_metrics, RTAX_MAX * sizeof(u32));
-}
+       u32 *p = dst_metrics_write_ptr(dst);
 
-static inline void dst_copy_metrics(struct dst_entry *dest, const struct dst_entry *src)
-{
-       dst_import_metrics(dest, src->_metrics);
-}
-
-static inline u32 *dst_metrics_ptr(struct dst_entry *dst)
-{
-       return dst->_metrics;
+       if (p)
+               p[metric-1] = val;
 }
 
 static inline u32