From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36970) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1d3Ymp-0002ym-7S for qemu-devel@nongnu.org; Wed, 26 Apr 2017 22:04:04 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1d3Ymo-0002HF-B6 for qemu-devel@nongnu.org; Wed, 26 Apr 2017 22:04:03 -0400 Date: Thu, 27 Apr 2017 10:03:52 +0800 From: Fam Zheng Message-ID: <20170427020352.GH9205@lemon.lan> References: <20170426033413.17192-1-famz@redhat.com> <20170426033413.17192-3-famz@redhat.com> <20170426093622.GB4538@noname.str.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170426093622.GB4538@noname.str.redhat.com> Subject: Re: [Qemu-devel] [PATCH v15 02/21] block: Define BLK_PERM_MAX List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin Wolf Cc: qemu-devel@nongnu.org, eblake@redhat.com, Max Reitz , qemu-block@nongnu.org On Wed, 04/26 11:36, Kevin Wolf wrote: > Am 26.04.2017 um 05:33 hat Fam Zheng geschrieben: > > This is the order of the largest possible permission. > > > > Signed-off-by: Fam Zheng > > --- > > include/block/block.h | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/include/block/block.h b/include/block/block.h > > index eb0565d..a798f10 100644 > > --- a/include/block/block.h > > +++ b/include/block/block.h > > @@ -224,6 +224,8 @@ enum { > > BLK_PERM_ALL = 0x1f, > > }; > > > > +#define BLK_PERM_MAX (64 - clz64((uint64_t)BLK_PERM_ALL)) > > Contrary to the commit message, this is the number of permission bits in > use (i.e. one more than the largest possible permission). You're using > it correctly, though, because your loop condition is i < BLK_PERM_MAX. > > This could use an updated commit message and a comment at the #define at > least. Ideally a less ambiguous name instead of the commit (because _MAX > seems to imply what the commit message currently says, not what it > really is), but I can't think of one. Good point. Given it another thought, using BLK_PERM_ALL in the loop condition is as easy. I'll drop this patch. Fam