diff options
| author |   Eric Dumazet <edumazet@google.com> | 2016-12-03 11:14:51 -0800 |
|---|---|---|
| committer |   David S. Miller <davem@davemloft.net> | 2016-12-05 13:32:22 -0500 |
| commit | 408f0a6c21e124cc4f6c7aa370b38aa47e55428d (patch) | |
| tree | 11a45f9e4e5cfd77e62d1363ad734e6fe753cd91 /net/ipv4 | |
| parent | tcp: tsq: add tsq_flags / tsq_enum (diff) | |
| download | linux-dev-408f0a6c21e124cc4f6c7aa370b38aa47e55428d.tar.xz linux-dev-408f0a6c21e124cc4f6c7aa370b38aa47e55428d.zip | |
tcp: tsq: remove one locked operation in tcp_wfree()
Instead of atomically clear TSQ_THROTTLED and atomically set TSQ_QUEUED
bits, use one cmpxchg() to perform a single locked operation.
Since the following patch will also set TCP_TSQ_DEFERRED here,
this cmpxchg() will make this addition free.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4')
| -rw-r--r-- | net/ipv4/tcp_output.c | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 8f0289b0fb24..4adaf8e1bb63 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -860,6 +860,7 @@ void tcp_wfree(struct sk_buff *skb) { struct sock *sk = skb->sk; struct tcp_sock *tp = tcp_sk(sk); + unsigned long flags, nval, oval; int wmem; /* Keep one reference on sk_wmem_alloc. @@ -877,11 +878,17 @@ void tcp_wfree(struct sk_buff *skb) if (wmem >= SKB_TRUESIZE(1) && this_cpu_ksoftirqd() == current) goto out; - if (test_and_clear_bit(TSQ_THROTTLED, &tp->tsq_flags) && - !test_and_set_bit(TSQ_QUEUED, &tp->tsq_flags)) { - unsigned long flags; + for (oval = READ_ONCE(tp->tsq_flags);; oval = nval) { struct tsq_tasklet *tsq; + if (!(oval & TSQF_THROTTLED) || (oval & TSQF_QUEUED)) + goto out; + + nval = (oval & ~TSQF_THROTTLED) | TSQF_QUEUED; + nval = cmpxchg(&tp->tsq_flags, oval, nval); + if (nval != oval) + continue; + /* queue this socket to tasklet queue */ local_irq_save(flags); tsq = this_cpu_ptr(&tsq_tasklet); |