From: Dave Taht <[email protected]>
On embedded devices in particular, large queues of small packets from the rx
path with a large truesize can exist. Reducing their size can reduce
memory pressure. skb_reduce_truesize is a helper function for doing this,
when needed.
---
include/linux/skbuff.h | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 6a2c34e..2080cb1 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1671,6 +1671,24 @@ static inline void pskb_trim_unique(struct sk_buff *skb,
unsigned int len)
BUG_ON(err);
}
+/*
+ * Caller wants to reduce memory needs before queueing skb
+ * The (expensive) copy should not be be done in fast path.
+ */
+static inline struct sk_buff *skb_reduce_truesize(struct sk_buff *skb)
+{
+ if (skb->truesize > 2 * SKB_TRUESIZE(skb->len)) {
+ struct sk_buff *nskb;
+ nskb = skb_copy_expand(skb, skb_headroom(skb), 0,
+ GFP_ATOMIC | __GFP_NOWARN);
+ if (nskb) {
+ __kfree_skb(skb);
+ skb = nskb;
+ }
+ }
+ return skb;
+}
+
/**
* skb_orphan - orphan a buffer
* @skb: buffer to orphan
--
1.7.9.5
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