netdev - Re: [PATCH] lib/rhashtable: reorder some inititalization sequences

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Message-ID: <20180515033719.t2jphtfjofc5v7ag@gondor.apana.org.au>
Date:   Tue, 15 May 2018 11:37:20 +0800
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     David Miller <davem@...emloft.net>
Cc:     dave@...olabs.net, akpm@...ux-foundation.org, tgraf@...g.ch,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        dbueso@...e.de
Subject: Re: [PATCH] lib/rhashtable: reorder some inititalization sequences

On Mon, May 14, 2018 at 10:52:13PM -0400, David Miller wrote:
> From: Davidlohr Bueso <dave@...olabs.net>
> Date: Mon, 14 May 2018 08:13:32 -0700
> 
> > rhashtable_init() allocates memory at the very end of the
> > call, once everything is setup; with the exception of the
> > nelems parameter. However, unless the user is doing something
> > bogus with params for which -EINVAL is returned, memory
> > allocation is the only operation that can trigger the call
> > to fail.
> > 
> > Thus move bucket_table_alloc() up such that we fail back to
> > the caller asap, instead of doing useless checks. This is
> > safe as the the table allocation isn't using the halfly
> > setup 'ht' structure and bucket_table_alloc() call chain only
> > ends up using the ht->nulls_base member in INIT_RHT_NULLS_HEAD.
> > 
> > Also move the locking initialization down to the end.
> > 
> > Signed-off-by: Davidlohr Bueso <dbueso@...e.de>
> 
> The user potentially "doing something bogus" is why the most
> expensive part of the initialization (the memory allocation)
> is done after everything else is validated.
> 
> I think it's best to keep things as-is.

I agree.

Thanks,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt