Commit 87151b86 authored Apr 10, 2012 by Eric Dumazet Committed by David S. Miller Apr 11, 2012

net: allow pskb_expand_head() to get maximum tailroom



Marc Merlin reported many order-1 allocations failures in TX path on its
wireless setup, that dont make any sense with MTU=1500 network, and non
SG capable hardware.

Turns out part of the problem comes from pskb_expand_head() not using
ksize() to get exact head size given by kmalloc(). Doing the same thing
than __alloc_skb() allows more tailroom in skb and can prevent future
reallocations.

As a bonus, struct skb_shared_info becomes cache line aligned.

Reported-by: Marc MERLIN <marc@merlins.org>
Tested-by: Marc MERLIN <marc@merlins.org>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 996304bb

net/core/skbuff.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -952,9 +952,11 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
		goto adjust_others;
		}

		data = kmalloc(size + sizeof(struct skb_shared_info), gfp_mask);
		data = kmalloc(size + SKB_DATA_ALIGN(sizeof(struct skb_shared_info)),
		gfp_mask);
		if (!data)
		goto nodata;
		size = SKB_WITH_OVERHEAD(ksize(data));

		/* Copy only real data... and, alas, header. This should be
		* optimized for the cases when header is void.

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