OpenWrt – Blame information for rev 1
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1 | office | 1 | From 4593a806e31119c5bd3faa00c7210ad862d515af Mon Sep 17 00:00:00 2001 |
2 | From: Dave Taht <dave.taht@bufferbloat.net> |
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3 | Date: Mon, 31 Dec 2012 10:02:21 -0800 |
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4 | Subject: [PATCH 3/7] skb_reduce_truesize: helper function for shrinking skbs |
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5 | whenever needed |
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6 | |||
7 | On embedded devices in particular, large queues of small packets from the rx |
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8 | path with a large truesize can exist. Reducing their size can reduce |
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9 | memory pressure. skb_reduce_truesize is a helper function for doing this, |
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10 | when needed. |
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11 | --- |
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12 | include/linux/skbuff.h | 18 ++++++++++++++++++ |
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13 | 1 file changed, 18 insertions(+) |
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14 | |||
15 | --- a/include/linux/skbuff.h |
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16 | +++ b/include/linux/skbuff.h |
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17 | @@ -2069,6 +2069,24 @@ static inline void pskb_trim_unique(stru |
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18 | BUG_ON(err); |
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19 | } |
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20 | |||
21 | +/* |
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22 | + * Caller wants to reduce memory needs before queueing skb |
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23 | + * The (expensive) copy should not be be done in fast path. |
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24 | + */ |
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25 | +static inline struct sk_buff *skb_reduce_truesize(struct sk_buff *skb) |
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26 | +{ |
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27 | + if (skb->truesize > 2 * SKB_TRUESIZE(skb->len)) { |
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28 | + struct sk_buff *nskb; |
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29 | + nskb = skb_copy_expand(skb, skb_headroom(skb), 0, |
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30 | + GFP_ATOMIC | __GFP_NOWARN); |
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31 | + if (nskb) { |
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32 | + __kfree_skb(skb); |
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33 | + skb = nskb; |
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34 | + } |
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35 | + } |
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36 | + return skb; |
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37 | +} |
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38 | + |
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39 | /** |
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40 | * skb_orphan - orphan a buffer |
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41 | * @skb: buffer to orphan |