openwrt/target/linux/generic/patches-4.1/656-skb_reduce_truesize-helper.patch
Stijn Tintel 2fc3680dd0 kernel: update kernel 4.1 to version 4.1.34
Refresh patches for all targets supporting 4.1 and not marked broken.
Compile-tested on all targets using 4.1 and not marked broken.

Changes to generic/610-netfilter_match_bypass_default_checks.patch based
on 84d489f64f.
Changes to generic/666-Add-support-for-MAP-E-FMRs-mesh-mode.patch based
on a90ee92337.

Signed-off-by: Stijn Tintel <stijn@linux-ipv6.be>
2016-10-24 20:25:14 +03:00

42 lines
1.2 KiB
Diff

From 4593a806e31119c5bd3faa00c7210ad862d515af Mon Sep 17 00:00:00 2001
From: Dave Taht <dave.taht@bufferbloat.net>
Date: Mon, 31 Dec 2012 10:02:21 -0800
Subject: [PATCH 3/7] skb_reduce_truesize: helper function for shrinking skbs
whenever needed
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(+)
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -2097,6 +2097,24 @@ static inline void pskb_trim_unique(stru
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