Messages in this thread | | | Date | Thu, 16 Aug 2007 10:11:05 +0800 | From | Herbert Xu <> | Subject | Re: [PATCH 0/24] make atomic_read() behave consistently across all architectures |
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On Thu, Aug 16, 2007 at 12:05:56PM +1000, Paul Mackerras wrote: > Herbert Xu writes: > > > See sk_stream_mem_schedule in net/core/stream.c: > > > > /* Under limit. */ > > if (atomic_read(sk->sk_prot->memory_allocated) < sk->sk_prot->sysctl_mem[0]) { > > if (*sk->sk_prot->memory_pressure) > > *sk->sk_prot->memory_pressure = 0; > > return 1; > > } > > > > /* Over hard limit. */ > > if (atomic_read(sk->sk_prot->memory_allocated) > sk->sk_prot->sysctl_mem[2]) { > > sk->sk_prot->enter_memory_pressure(); > > goto suppress_allocation; > > } > > > > We don't need to reload sk->sk_prot->memory_allocated here. > > Are you sure? How do you know some other CPU hasn't changed the value > in between?
Yes I'm sure, because we don't care if others have increased the reservation.
Note that even if we did we'd be using barriers so volatile won't do us any good here.
Cheers, -- Visit Openswan at http://www.openswan.org/ Email: Herbert Xu ~{PmV>HI~} <herbert@gondor.apana.org.au> Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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