Re: [PATCH 0/24] make atomic_read() behave consistently across all architectures

From: Paul Mackerras
Date: Wed Aug 15 2007 - 22:06:41 EST


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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