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Commit c8753d55 authored by Vijay Subramanian's avatar Vijay Subramanian Committed by David S. Miller
Browse files

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: default avatarVijay Subramanian <subramanian.vijay@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 9fab426d

include/linux/skbuff.h

+4 −3
Original line number Diff line number Diff line
@@ -339,9 +339,10 @@ struct skb_shared_info { 




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 {

net/core/skbuff.c

+4 −4
Original line number Diff line number Diff line
@@ -265,7 +265,7 @@ struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask, 
		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 @@ static void kfree_skbmem(struct sk_buff *skb) 
		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 @@ static void kfree_skbmem(struct sk_buff *skb) 
			/* The clone portion is available for

			 * fast-cloning again.

			 */

			skb->fclone = SKB_FCLONE_UNAVAILABLE;

			skb->fclone = SKB_FCLONE_FREE;

		}

		break;

	}
@@ -874,7 +874,7 @@ struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t gfp_mask) 
		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