OpenWrt – Blame information for rev 2
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Rev | Author | Line No. | Line |
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1 | office | 1 | From 408f0a6c21e124cc4f6c7aa370b38aa47e55428d Mon Sep 17 00:00:00 2001 |
2 | From: Eric Dumazet <edumazet@google.com> |
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3 | Date: Sat, 3 Dec 2016 11:14:51 -0800 |
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4 | Subject: [PATCH 02/10] tcp: tsq: remove one locked operation in tcp_wfree() |
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5 | |||
6 | Instead of atomically clear TSQ_THROTTLED and atomically set TSQ_QUEUED |
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7 | bits, use one cmpxchg() to perform a single locked operation. |
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8 | |||
9 | Since the following patch will also set TCP_TSQ_DEFERRED here, |
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10 | this cmpxchg() will make this addition free. |
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11 | |||
12 | Signed-off-by: Eric Dumazet <edumazet@google.com> |
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13 | Signed-off-by: David S. Miller <davem@davemloft.net> |
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14 | --- |
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15 | net/ipv4/tcp_output.c | 13 ++++++++++--- |
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16 | 1 file changed, 10 insertions(+), 3 deletions(-) |
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17 | |||
18 | --- a/net/ipv4/tcp_output.c |
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19 | +++ b/net/ipv4/tcp_output.c |
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20 | @@ -865,6 +865,7 @@ void tcp_wfree(struct sk_buff *skb) |
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21 | { |
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22 | struct sock *sk = skb->sk; |
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23 | struct tcp_sock *tp = tcp_sk(sk); |
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24 | + unsigned long flags, nval, oval; |
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25 | int wmem; |
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26 | |||
27 | /* Keep one reference on sk_wmem_alloc. |
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28 | @@ -882,11 +883,17 @@ void tcp_wfree(struct sk_buff *skb) |
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29 | if (wmem >= SKB_TRUESIZE(1) && this_cpu_ksoftirqd() == current) |
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30 | goto out; |
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31 | |||
32 | - if (test_and_clear_bit(TSQ_THROTTLED, &tp->tsq_flags) && |
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33 | - !test_and_set_bit(TSQ_QUEUED, &tp->tsq_flags)) { |
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34 | - unsigned long flags; |
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35 | + for (oval = READ_ONCE(tp->tsq_flags);; oval = nval) { |
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36 | struct tsq_tasklet *tsq; |
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37 | |||
38 | + if (!(oval & TSQF_THROTTLED) || (oval & TSQF_QUEUED)) |
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39 | + goto out; |
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40 | + |
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41 | + nval = (oval & ~TSQF_THROTTLED) | TSQF_QUEUED; |
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42 | + nval = cmpxchg(&tp->tsq_flags, oval, nval); |
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43 | + if (nval != oval) |
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44 | + continue; |
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45 | + |
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46 | /* queue this socket to tasklet queue */ |
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47 | local_irq_save(flags); |
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48 | tsq = this_cpu_ptr(&tsq_tasklet); |