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From: David Miller <davem@davemloft.net>
To: arnd@arndb.de
Cc: jhs@mojatatu.com, xiyou.wangcong@gmail.com, jiri@resnulli.us,
	kuba@kernel.org, gnault@redhat.com, vladbu@mellanox.com,
	lucien.xin@gmail.com, pablo@netfilter.org,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] flow_dissector: work around stack frame size warning
Date: Mon, 01 Jun 2020 11:52:22 -0700 (PDT)	[thread overview]
Message-ID: <20200601.115222.628560714795578081.davem@davemloft.net> (raw)
In-Reply-To: <20200529201413.397679-1-arnd@arndb.de>

From: Arnd Bergmann <arnd@arndb.de>
Date: Fri, 29 May 2020 22:13:58 +0200

> The fl_flow_key structure is around 500 bytes, so having two of them
> on the stack in one function now exceeds the warning limit after an
> otherwise correct change:
> 
> net/sched/cls_flower.c:298:12: error: stack frame size of 1056 bytes in function 'fl_classify' [-Werror,-Wframe-larger-than=]
> 
> I suspect the fl_classify function could be reworked to only have one
> of them on the stack and modify it in place, but I could not work out
> how to do that.
> 
> As a somewhat hacky workaround, move one of them into an out-of-line
> function to reduce its scope. This does not necessarily reduce the stack
> usage of the outer function, but at least the second copy is removed
> from the stack during most of it and does not add up to whatever is
> called from there.
> 
> I now see 552 bytes of stack usage for fl_classify(), plus 528 bytes
> for fl_mask_lookup().
> 
> Fixes: 58cff782cc55 ("flow_dissector: Parse multiple MPLS Label Stack Entries")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Applied, thanks.

      parent reply	other threads:[~2020-06-01 18:52 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-29 20:13 [PATCH] flow_dissector: work around stack frame size warning Arnd Bergmann
2020-05-30  4:49 ` Cong Wang
2020-05-30 16:43 ` Guillaume Nault
2020-06-01 18:52 ` David Miller [this message]

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