net: Cleanup skb cloning by adding SKB_FCLONE_FREE
SKB_FCLONE_UNAVAILABLE has overloaded meaning depending on type of skb.
1: If skb is allocated from head_cache, it indicates fclone is not available.
2: If skb is a companion fclone skb (allocated from fclone_cache), it indicates
it is available to be used.
To avoid confusion for case 2 above, this patch replaces
SKB_FCLONE_UNAVAILABLE with SKB_FCLONE_FREE where appropriate. For fclone
companion skbs, this indicates it is free for use.
SKB_FCLONE_UNAVAILABLE will now simply indicate skb is from head_cache and
cannot / will not have a companion fclone.
Signed-off-by: Vijay Subramanian <subramanian.vijay@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 7c5036d..3a5ec76 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -339,9 +339,10 @@
enum {
- SKB_FCLONE_UNAVAILABLE,
- SKB_FCLONE_ORIG,
- SKB_FCLONE_CLONE,
+ SKB_FCLONE_UNAVAILABLE, /* skb has no fclone (from head_cache) */
+ SKB_FCLONE_ORIG, /* orig skb (from fclone_cache) */
+ SKB_FCLONE_CLONE, /* companion fclone skb (from fclone_cache) */
+ SKB_FCLONE_FREE, /* this companion fclone skb is available */
};
enum {
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index a0b312f..28916e4 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -265,7 +265,7 @@
skb->fclone = SKB_FCLONE_ORIG;
atomic_set(&fclones->fclone_ref, 1);
- fclones->skb2.fclone = SKB_FCLONE_UNAVAILABLE;
+ fclones->skb2.fclone = SKB_FCLONE_FREE;
fclones->skb2.pfmemalloc = pfmemalloc;
}
out:
@@ -542,7 +542,7 @@
fclones = container_of(skb, struct sk_buff_fclones, skb2);
/* Warning : We must perform the atomic_dec_and_test() before
- * setting skb->fclone back to SKB_FCLONE_UNAVAILABLE, otherwise
+ * setting skb->fclone back to SKB_FCLONE_FREE, otherwise
* skb_clone() could set clone_ref to 2 before our decrement.
* Anyway, if we are going to free the structure, no need to
* rewrite skb->fclone.
@@ -553,7 +553,7 @@
/* The clone portion is available for
* fast-cloning again.
*/
- skb->fclone = SKB_FCLONE_UNAVAILABLE;
+ skb->fclone = SKB_FCLONE_FREE;
}
break;
}
@@ -874,7 +874,7 @@
return NULL;
if (skb->fclone == SKB_FCLONE_ORIG &&
- n->fclone == SKB_FCLONE_UNAVAILABLE) {
+ n->fclone == SKB_FCLONE_FREE) {
n->fclone = SKB_FCLONE_CLONE;
/* As our fastclone was free, clone_ref must be 1 at this point.
* We could use atomic_inc() here, but it is faster