net: dst: remove gc leftovers

Get rid of some obsolete gc-related documentation and macros that were
missed in commit 5b7c9a8ff8 ("net: remove dst gc related code").

CC: Wei Wang <weiwan@google.com>
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Acked-by: Wei Wang <weiwan@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/dst.h

@@ -19,17 +19,6 @@
 #include <net/neighbour.h>
 #include <asm/processor.h>
 
-#define DST_GC_MIN	(HZ/10)
-#define DST_GC_INC	(HZ/2)
-#define DST_GC_MAX	(120*HZ)
-
-/* Each dst_entry has reference count and sits in some parent list(s).
- * When it is removed from parent list, it is "freed" (dst_free).
- * After this it enters dead state (dst->obsolete > 0) and if its refcnt
- * is zero, it can be destroyed immediately, otherwise it is added
- * to gc list and garbage collector periodically checks the refcnt.
- */
-
 struct sk_buff;
 
 struct dst_entry {

net/core/dst.c

@@ -26,23 +26,6 @@
 #include <net/dst.h>
 #include <net/dst_metadata.h>
 
-/*
- * Theory of operations:
- * 1) We use a list, protected by a spinlock, to add
- *    new entries from both BH and non-BH context.
- * 2) In order to keep spinlock held for a small delay,
- *    we use a second list where are stored long lived
- *    entries, that are handled by the garbage collect thread
- *    fired by a workqueue.
- * 3) This list is guarded by a mutex,
- *    so that the gc_task and dst_dev_event() can be synchronized.
- */
-
-/*
- * We want to keep lock & list close together
- * to dirty as few cache lines as possible in __dst_free().
- * As this is not a very strong hint, we dont force an alignment on SMP.
- */
 int dst_discard_out(struct net *net, struct sock *sk, struct sk_buff *skb)
 {
 	kfree_skb(skb);

net/ipv4/route.c

@@ -1176,7 +1176,7 @@ static struct dst_entry *ipv4_dst_check(struct dst_entry *dst, u32 cookie)
 	 *
 	 * When a PMTU/redirect information update invalidates a route,
 	 * this is indicated by setting obsolete to DST_OBSOLETE_KILL or
-	 * DST_OBSOLETE_DEAD by dst_free().
+	 * DST_OBSOLETE_DEAD.
 	 */
 	if (dst->obsolete != DST_OBSOLETE_FORCE_CHK || rt_is_expired(rt))
 		return NULL;