netdev - Re: [PATCH net] net: avoid possible false sharing in sk_leave_memory

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Date:   Wed, 9 Oct 2019 21:32:09 -0700
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     Eric Dumazet <edumazet@...gle.com>
Cc:     "David S . Miller" <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>,
        Eric Dumazet <eric.dumazet@...il.com>
Subject: Re: [PATCH net] net: avoid possible false sharing in
 sk_leave_memory_pressure()

On Wed,  9 Oct 2019 12:55:53 -0700, Eric Dumazet wrote:
> As mentioned in https://github.com/google/ktsan/wiki/READ_ONCE-and-WRITE_ONCE#it-may-improve-performance
> a C compiler can legally transform :
> 
> if (memory_pressure && *memory_pressure)
>         *memory_pressure = 0;
> 
> to :
> 
> if (memory_pressure)
>         *memory_pressure = 0;
> 
> Fixes: 0604475119de ("tcp: add TCPMemoryPressuresChrono counter")
> Fixes: 180d8cd942ce ("foundations of per-cgroup memory pressure controlling.")
> Fixes: 3ab224be6d69 ("[NET] CORE: Introducing new memory accounting interface.")
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>

Applied, thanks!