From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932454AbdBVLiN (ORCPT ); Wed, 22 Feb 2017 06:38:13 -0500 Received: from mail2-relais-roc.national.inria.fr ([192.134.164.83]:29487 "EHLO mail2-relais-roc.national.inria.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932369AbdBVLiF (ORCPT ); Wed, 22 Feb 2017 06:38:05 -0500 X-IronPort-AV: E=Sophos;i="5.35,193,1484002800"; d="scan'208";a="261629012" Date: Wed, 22 Feb 2017 12:36:36 +0100 (CET) From: Julia Lawall X-X-Sender: jll@hadrien To: SIMRAN SINGHAL cc: outreachy-kernel , gregkh@linuxfoundation.org, devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org Subject: Re: [Outreachy kernel] [PATCH v2 2/7] staging: most: Using macro DIV_ROUND_UP In-Reply-To: Message-ID: References: <20170222091015.GA11058@singhal-Inspiron-5558> User-Agent: Alpine 2.20 (DEB 67 2015-01-07) MIME-Version: 1.0 Content-Type: multipart/mixed; BOUNDARY="8323329-151047132-1487763396=:3145" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --8323329-151047132-1487763396=:3145 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT On Wed, 22 Feb 2017, SIMRAN SINGHAL wrote: > > > On Wednesday, February 22, 2017 at 2:57:17 PM UTC+5:30, Julia Lawall wrote: > > @@ -117,7 +118,7 @@ static int alloc_dbr(u16 size) > >                  return DBR_SIZE; /* out of memory */ > > > >          for (i = 0; i < DBR_MAP_SIZE; i++) { > > -                u32 const blocks = (size + DBR_BLOCK_SIZE - > 1) / DBR_BLOCK_SIZE; > > +                u32 const blocks = DIV_ROUND_UP(size, > DBR_BLOCK_SIZE); > >                  u32 mask = ~((~(u32)0) << blocks); > > Totally unrelated to DIV_ROUND_UP, would this code be a > candidate for > GENMASK? > >   > Not sure, what you are trying to say. There was a discussion on the list recently about GENMASK, which allows to create a mask containing a sequence of 1s, like 000011110000. It looks like that is what is being done here, because ~0 is 11111111 and then it ie being shifted left and all the bits inverted. But Joe had another suggestion. One could double check that his suggestion gives the right result. julia > >   > > julia > > > > >                  do { > > @@ -137,7 +138,7 @@ static int alloc_dbr(u16 size) > >  static void free_dbr(int offs, int size) > >  { > >          int block_idx = offs / DBR_BLOCK_SIZE; > > -        u32 const blocks = (size + DBR_BLOCK_SIZE - 1) / > DBR_BLOCK_SIZE; > > +        u32 const blocks = DIV_ROUND_UP(size, > DBR_BLOCK_SIZE); > >          u32 mask = ~((~(u32)0) << blocks); > > > >          mask <<= block_idx % 32; > > -- > > 2.7.4 > > > > -- > > You received this message because you are subscribed to the > Google Groups "outreachy-kernel" group. > > To unsubscribe from this group and stop receiving emails from > it, send an email to outreachy-kern...@googlegroups.com. > > To post to this group, send email to > outreach...@googlegroups.com. > > To view this discussion on the web visithttps://groups.google.com/d/msgid/outreachy-kernel/20170222091015.GA11058%4 > 0singhal-Inspiron-5558. > > For more options, visit https://groups.google.com/d/optout. > > > > -- > You received this message because you are subscribed to the Google Groups > "outreachy-kernel" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to outreachy-kernel+unsubscribe@googlegroups.com. > To post to this group, send email to outreachy-kernel@googlegroups.com. > To view this discussion on the web visithttps://groups.google.com/d/msgid/outreachy-kernel/d1716b00-a408-4f3c-8c17- > 04a70acca4dd%40googlegroups.com. > For more options, visit https://groups.google.com/d/optout. > > --8323329-151047132-1487763396=:3145--