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Date: Thu, 16 Aug 2007 12:05:56 +1000
From: Paul Mackerras <paulus@samba.org>
To: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Christoph Lameter <clameter@sgi.com>,
       "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
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Subject: Re: [PATCH 0/24] make atomic_read() behave consistently across all architectures
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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?

Paul.
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