Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752874AbZK1KFY (ORCPT ); Sat, 28 Nov 2009 05:05:24 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751391AbZK1KFX (ORCPT ); Sat, 28 Nov 2009 05:05:23 -0500 Received: from ozlabs.org ([203.10.76.45]:57709 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751087AbZK1KFX (ORCPT ); Sat, 28 Nov 2009 05:05:23 -0500 From: Rusty Russell To: Matt Mackall Subject: Re: [PATCH 1/2] hw_random: core updates to allow more efficient drivers Date: Sat, 28 Nov 2009 20:35:26 +1030 User-Agent: KMail/1.12.2 (Linux/2.6.31-15-generic; KDE/4.3.2; i686; ; ) Cc: Ian Molton , linux-kernel@vger.kernel.org References: <1259177252.2858.17.camel@calx> <1259195127-20086-2-git-send-email-ian.molton@collabora.co.uk> <1259197403.2858.88.camel@calx> In-Reply-To: <1259197403.2858.88.camel@calx> MIME-Version: 1.0 Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <200911282035.26847.rusty@rustcorp.com.au> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1187 Lines: 34 On Thu, 26 Nov 2009 11:33:23 am Matt Mackall wrote: > On Thu, 2009-11-26 at 00:25 +0000, Ian Molton wrote: > > #define PFX RNG_MODULE_NAME ": " > > #define RNG_MISCDEV_MINOR 183 /* official */ > > +#define RNG_BUFFSIZE 64 > > How about just: > > static u8 rng_buffer[RNG_BUFFSIZE] __cacheline_aligned; > > And lose all the kmalloc and kfree code? The memory use will be smaller, > even when the buffer isn't needed. And might as well just #defube RNG_BUFFSIZE SMP_CACHE_BYTES (or use SMP_CACHE_BYTES here and sizeof() elsewhere). > > + if (!data_avail) { > > + bytes_read = rng_get_data(current_rng, rng_buffer, > > + RNG_BUFFSIZE, !(filp->f_flags & O_NONBLOCK)); > > No need to pass rng_buffer to the helper as there's only one with global > scope. Naah, I like the separation; it matches the rest of the kernel and means we can get funky with buffer management in 10 years time when we rewrite this again. Thanks, Rusty. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/