From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [PATCH] Asynchronous scan support for libata Date: Sat, 08 Sep 2007 19:40:27 +0200 Message-ID: <46E2DE8B.5040708@gmail.com> References: <20070906210505.GF27404@parisc-linux.org> <46E258F3.20805@gmail.com> <20070908171917.GC6809@parisc-linux.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from wa-out-1112.google.com ([209.85.146.176]:44701 "EHLO wa-out-1112.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754281AbXIHRmJ (ORCPT ); Sat, 8 Sep 2007 13:42:09 -0400 Received: by wa-out-1112.google.com with SMTP id v27so948063wah for ; Sat, 08 Sep 2007 10:42:08 -0700 (PDT) In-Reply-To: <20070908171917.GC6809@parisc-linux.org> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Matthew Wilcox Cc: Jeff Garzik , linux-ide@vger.kernel.org Matthew Wilcox wrote: > On Sat, Sep 08, 2007 at 05:10:27PM +0900, Tejun Heo wrote: >> I think it's generally okay although it would need to spend quite some >> time in -mm and we'll need to exclude several drivers which require >> host-wide silence for mode programming (the current code is buggy but >> sequential probing hides it pretty well) till host-wide exclusion is >> implemented. > > Can you tell me a bit more about these drivers? Would it be possible to > convert them to one host/many channels, which would give us the exclusion > we want? IIRC, sata_promise is of this type and there probably are a few old PATA ones. Ports on the host are mostly independent. There's no need for cross-port synchronization for most of the time but configuring transfer mode requires host-wide quiescence. Currently, the planned way to fix the problem is to implement host-wide exclusion mechanism in the error handler (summon EH of all other threads and wait till all of them are parked) and it's on top of the TODO list, so I don't think it will take too long. Thanks. -- tejun