Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932807Ab1DNTBU (ORCPT ); Thu, 14 Apr 2011 15:01:20 -0400 Received: from smtp-out.google.com ([216.239.44.51]:45560 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932232Ab1DNTBS convert rfc822-to-8bit (ORCPT ); Thu, 14 Apr 2011 15:01:18 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=google.com; s=beta; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc:content-type:content-transfer-encoding; b=H89vahQYk4G222rW4cYXfux3WfqVsoafPTVLaNYQreDy/EIxLRQFcd/cbnKzkdpuY5 8fb4VcW5ND8wbTamgVsw== MIME-Version: 1.0 In-Reply-To: <20110413102947.3bf1cc88@lxorguk.ukuu.org.uk> References: <1302641290-30212-1-git-send-email-natg@google.com> <1302641387-30264-1-git-send-email-natg@google.com> <20110413070259.GE4070@infomag.iguana.be> <20110413102947.3bf1cc88@lxorguk.ukuu.org.uk> From: Mike Waychison Date: Thu, 14 Apr 2011 14:00:49 -0500 Message-ID: Subject: Re: [PATCH v5 1/2] Use "request_muxed_region" in it87 watchdog drivers To: Alan Cox Cc: Wim Van Sebroeck , Nat Gurumoorthy , Jean Delvare , Guenter Roeck , lm-sensors@lm-sensors.org, linux-kernel@vger.kernel.org, linux-watchdog@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1870 Lines: 58 On Wed, Apr 13, 2011 at 4:29 AM, Alan Cox wrote: > On Wed, 13 Apr 2011 09:03:00 +0200 > Wim Van Sebroeck wrote: > >> Hi Nat, >> >> > + ? (void) request_muxed_region(REG, 2, NAME); >> >> Why do we need to typecast this? Can't we just use >> + ? ? request_muxed_region(REG, 2, NAME); > > We really ought to use > > ? ? ? ?if () > > in theory the request can fail if someone has hogged the resource and not > muxed it. I'm not clear what the right thing to do in that case is - > given it should never happen I guess log an error and bail out but that's > a rather bigger change and perhaps should be a follow up patch ? > request_muxed_region() is sorta gross: it's essentially acting like a lock, meant to be used for short periods of time, but it can fail if someone else decides it should. Would it make more sense to have drivers that need to use the current request_muxed_region() be able to force a region into a mux-only state at driver init? That would lead to much less contorted code to handle the off-chance that the request_muxed_region() fails. Ie: Driver init: if (!request_muxed_region(base, size, DRV_NAME)) goto cleanup_driver_init_failed; Driver cleanup release_muxed_region(base, size); /* returns void */ And then within drivers: use_muxed_region(base, size); /* sleeps until region is usable -- returns void */ /* Do stuff */ unuse_muxed_region(base, size); /* returns void */ I realize the above example re-uses the 'request_muxed_region()' name, but at least this would be much more consistent with how request_region is used in other drivers. -- 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/