From mboxrd@z Thu Jan 1 00:00:00 1970 From: linas@austin.ibm.com (Linas Vepstas) Subject: Re: [Cbe-oss-dev] [PATCH 4/10] spidernet: zero out a pointer. Date: Tue, 22 May 2007 18:35:18 -0500 Message-ID: <20070522233517.GU5921@austin.ibm.com> References: <20070516215605.GA4325@austin.ibm.com> <20070516220928.GD4997@austin.ibm.com> <1179358376.4142.4.camel@concordia.ozlabs.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Jeff Garzik , netdev@vger.kernel.org, cbe-oss-dev@ozlabs.org To: Michael Ellerman Return-path: Received: from e3.ny.us.ibm.com ([32.97.182.143]:35311 "EHLO e3.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757285AbXEVXfV (ORCPT ); Tue, 22 May 2007 19:35:21 -0400 Received: from d01relay04.pok.ibm.com (d01relay04.pok.ibm.com [9.56.227.236]) by e3.ny.us.ibm.com (8.13.8/8.13.8) with ESMTP id l4MMXFXT015143 for ; Tue, 22 May 2007 18:33:15 -0400 Received: from d01av04.pok.ibm.com (d01av04.pok.ibm.com [9.56.224.64]) by d01relay04.pok.ibm.com (8.13.8/8.13.8/NCO v8.3) with ESMTP id l4MNZJhl540866 for ; Tue, 22 May 2007 19:35:19 -0400 Received: from d01av04.pok.ibm.com (loopback [127.0.0.1]) by d01av04.pok.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id l4MNZINX004787 for ; Tue, 22 May 2007 19:35:18 -0400 Content-Disposition: inline In-Reply-To: <1179358376.4142.4.camel@concordia.ozlabs.ibm.com> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Thu, May 17, 2007 at 09:32:56AM +1000, Michael Ellerman wrote: > > + hwdescr->buf_addr = 0x0; > > If you're going to be paranoid, shouldn't you do something here to make > sure the value's hit the device? I thought the whole point of paranoia is that its inexplicable. Here's a delusional reply: I didn't see any point to it. 1) a wmb would add overhead 2) the hardware is supposed to be looking at the status flag, anyway, and not misbehaving. 3) there is a wmb when the descr is actually refilled in such a way as to actually mean something to the hardware. All that I really acomplished here is a minor trick to aid in debug printing when looking for something bad. --linas