linux-kernel - RE: [PATCH v2] net: sctp: Don't use 64 kilobyte lookup table for four elements

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Message-ID: <063D6719AE5E284EB5DD2968C1650D6D1CBA41B0@AcuExch.aculab.com>
Date:	Mon, 28 Sep 2015 14:12:26 +0000
From:	David Laight <David.Laight@...LAB.COM>
To:	'Neil Horman' <nhorman@...driver.com>,
	Denys Vlasenko <dvlasenk@...hat.com>
CC:	"David S. Miller" <davem@...emloft.net>,
	Vlad Yasevich <vyasevich@...il.com>,
	Marcelo Ricardo Leitner <marcelo.leitner@...il.com>,
	"linux-sctp@...r.kernel.org" <linux-sctp@...r.kernel.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v2] net: sctp: Don't use 64 kilobyte lookup table for
 four elements

From: Neil Horman
> Sent: 28 September 2015 14:51
> On Mon, Sep 28, 2015 at 02:34:04PM +0200, Denys Vlasenko wrote:
> > Seemingly innocuous sctp_trans_state_to_prio_map[] array
> > is way bigger than it looks, since
> > "[SCTP_UNKNOWN] = 2" expands into "[0xffff] = 2" !
> >
> > This patch replaces it with switch() statement.

What about just adding 1 (and masking) before indexing the array?
That might require a static inline function with a local static array.

Or define the array as (say) [16] and just mask the state before using
it as an index?

	David

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