Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758667Ab1E0DiS (ORCPT ); Thu, 26 May 2011 23:38:18 -0400 Received: from mail-pw0-f46.google.com ([209.85.160.46]:40970 "EHLO mail-pw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753096Ab1E0DiR (ORCPT ); Thu, 26 May 2011 23:38:17 -0400 Date: Thu, 26 May 2011 21:38:15 -0600 From: Grant Likely To: Milton Miller Cc: Thomas Gleixner , linux-kernel@vger.kernel.org Subject: Re: [PATCH RFC 4/4] irq: allow a per-allocation upper limit when allocating irqs Message-ID: <20110527033815.GN5032@ponder.secretlab.ca> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1603 Lines: 38 On Wed, May 25, 2011 at 01:34:18AM -0500, Milton Miller wrote: > Allow the option to specify an upper limit to the irq numbers for > each allocation. The limit is non-inclusive, and 0 means no limit > needed by caller. > > Some irq chips can support a relative large and arbitrary range, > but not infinite. For example, they may use the linux irq number > as the msi desciptor data, which for msi is 16 bits. > > Since e7bcecb7b1 (genirq: Make nr_irqs runtime expandable), checking > NR_IRQS or even nr_irqs is not sufficient to enforce such requirements > when sparse irqs are configured. > > Based on an irc discussion, make the limit per call instead of an > arch callback or global setting. > > If the requested count is above the limit, return -ENOMEM as if > nr_irqs could not be expanded, assuming the limit was specified at > a different layer than the count. > > This code does not try to keep the prior semantics of irq_alloc_descs > when irq was non-negative but not equal to from. I believe it was an > implementation artifact instead of a designed feature that one could > specify search starting from 4 and fail if the allocated irq was not > exactly 6, confirming that the intervening irqs were reserved. > > Suggested-by: Thomas Gleixner > Signed-off-by: Milton Miller Looks good to me/ g. -- 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/