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

Saeed Mahameed
2018-11-02T22:07:02Z

On Fri, 2018-11-02 at 14:39 -0700, Eric Dumazet wrote:
>
> 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.
>

hmm, you are right, i was thinking that mlx5e_get_Stats will trigger a
work to update stats and grab the state_lock, but for sw stats this is
not the case it is done in place.

BTW memcpy itself is not thread safe.