Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756111Ab1BIXfv (ORCPT ); Wed, 9 Feb 2011 18:35:51 -0500 Received: from ovro.ovro.caltech.edu ([192.100.16.2]:58997 "EHLO ovro.ovro.caltech.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755920Ab1BIXft (ORCPT ); Wed, 9 Feb 2011 18:35:49 -0500 Date: Wed, 9 Feb 2011 15:35:45 -0800 From: "Ira W. Snyder" To: Dmitry Torokhov Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] misc: add CARMA DATA-FPGA Access Driver Message-ID: <20110209233544.GA5303@ovro.caltech.edu> References: <1297208267-27087-1-git-send-email-iws@ovro.caltech.edu> <1297208267-27087-2-git-send-email-iws@ovro.caltech.edu> <20110209083325.GA7256@core.coreip.homeip.net> <20110209173532.GB21766@ovro.caltech.edu> <20110209182740.GC23867@core.coreip.homeip.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110209182740.GC23867@core.coreip.homeip.net> User-Agent: Mutt/1.5.20 (2009-06-14) X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.2.6 (ovro.ovro.caltech.edu); Wed, 09 Feb 2011 15:35:46 -0800 (PST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1247 Lines: 32 On Wed, Feb 09, 2011 at 10:27:40AM -0800, Dmitry Torokhov wrote: [ snip stuff I've already fixed in the next version ] > > > > The requirement is that the device stay open during reconfiguration. > > This provides for that. Readers just block for as long as the device is > > not producing data. > > OK, you still need to make sure you do not touch free/used buffer while > device is disabled. Also, you need to kick readers if you unbind the > driver, so maybe a new flag priv->exists should be introduced and > checked. > I don't understand what you mean by "kick readers if you unbind the driver". The kernel automatically increases the refcount on a module when a process is using the module. This shows up in the "Used by" column of lsmod's output. The kernel will not let you rmmod a module with a non-zero refcount. You cannot get into the situation where you have rmmod'ed the module and a reader is still blocking in read()/poll(). Thanks for the review. A v6 is coming right up. Ira -- 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/