linux-kernel - Re: [PATCH] net/mlx5e: fix high stack usage

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Date:   Fri, 2 Nov 2018 14:39:11 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Saeed Mahameed <saeedm@...lanox.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "arnd@...db.de" <arnd@...db.de>,
        "leon@...nel.org" <leon@...nel.org>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Moshe Shemesh <moshe@...lanox.com>,
        "linux-rdma@...r.kernel.org" <linux-rdma@...r.kernel.org>,
        Boris Pismenny <borisp@...lanox.com>,
        Tariq Toukan <tariqt@...lanox.com>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        Eran Ben Elisha <eranbe@...lanox.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Ilya Lesokhin <ilyal@...lanox.com>,
        Kamal Heib <kamalh@...lanox.com>
Subject: Re: [PATCH] net/mlx5e: fix high stack usage



On 11/02/2018 02:05 PM, Saeed Mahameed wrote:
 
> temp will be mem copied to priv->stats.sw at the end,
> memcpy(&priv->stats.sw, &s, sizeof(s)); 
> 
> one other way to solve this as suggested by Andrew, is to get rid of
> the temp var and make it point directly to priv->stats.sw 
> 

What about concurrency ?

This temp variable is there to make sure concurrent readers of stats might
not see mangle data (because another 'reader' just did a memset() and is doing the folding)


mlx5e_get_stats() can definitely be run at the same time by multiple threads.