netdev - Re: [PATCH v2 net] tcp: md5: do not use alloc

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Message-Id: <20141025.161109.291627513614647003.davem@davemloft.net>
Date:	Sat, 25 Oct 2014 16:11:09 -0400 (EDT)
From:	David Miller <davem@...emloft.net>
To:	eric.dumazet@...il.com
Cc:	dsahern@...il.com, cdleonard@...il.com, netdev@...r.kernel.org,
	jtoppins@...ulusnetworks.com
Subject: Re: [PATCH v2 net] tcp: md5: do not use alloc_percpu()

From: Eric Dumazet <eric.dumazet@...il.com>
Date: Thu, 23 Oct 2014 12:58:58 -0700

> From: Eric Dumazet <edumazet@...gle.com>
> 
> percpu tcp_md5sig_pool contains memory blobs that ultimately
> go through sg_set_buf().
> 
> -> sg_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf));
> 
> This requires that whole area is in a physically contiguous portion
> of memory. And that @buf is not backed by vmalloc().
> 
> Given that alloc_percpu() can use vmalloc() areas, this does not
> fit the requirements.
> 
> Replace alloc_percpu() by a static DEFINE_PER_CPU() as tcp_md5sig_pool
> is small anyway, there is no gain to dynamically allocate it.
> 
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> Fixes: 765cf9976e93 ("tcp: md5: remove one indirection level in tcp_md5sig_pool")
> Reported-by: Crestez Dan Leonard <cdleonard@...il.com>

Applied and queued up for -stable, thanks Eric.

Longer term we should do a proper shash/ahash conversion of the tcp md5
code, using the rules provided by Herbert Xu.

Thanks.
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