From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762768AbXGEUxs (ORCPT ); Thu, 5 Jul 2007 16:53:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1761543AbXGEUxd (ORCPT ); Thu, 5 Jul 2007 16:53:33 -0400 Received: from smtp-out001.kontent.com ([81.88.40.215]:38070 "EHLO smtp-out.kontent.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761461AbXGEUxc convert rfc822-to-8bit (ORCPT ); Thu, 5 Jul 2007 16:53:32 -0400 From: Oliver Neukum To: linux-pm@lists.linux-foundation.org Subject: Re: [linux-pm] Re: [PATCH] Remove process freezer from suspend to RAM pathway Date: Thu, 5 Jul 2007 22:53:34 +0200 User-Agent: KMail/1.9.7 Cc: Miklos Szeredi , mjg59@srcf.ucam.org, linux-kernel@vger.kernel.org, pavel@ucw.cz, johannes@sipsolutions.net References: <18059.10554.955290.148535@cargo.ozlabs.ibm.com> <200707052249.45495.oliver@neukum.org> In-Reply-To: <200707052249.45495.oliver@neukum.org> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8BIT Content-Disposition: inline Message-Id: <200707052253.34817.oliver@neukum.org> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Am Donnerstag, 5. Juli 2007 schrieb Oliver Neukum: > Am Donnerstag, 5. Juli 2007 schrieb Miklos Szeredi: > > > > Yes, fuse could handle being frozen there.  However that would only > > > > solve part of the problem: an operation waiting for a reply could be > > > > holding a VFS mutex and some other task may be blocked on that mutex. > > > > > > > > How would you solve freezing those tasks? > > > > > > OK, you made me reach for literatur on theoretical computer science. > > > > > > IMHO the range of actions a fuse server is inherently limited. > > > You must never ever block on a lock one of your clients is holding. In > > > this case the limitation is not influenced by the freezer. > > > > Obviously.  But I wasn't about the server trying to acquire a lock > > held by a client.  I was talking about a client trying to acquire a > > lock held by _another_ client. > > > > If this coincides with the server (or some other task which the server > > is depending on) being frozen before the clients, the freezer has a > > problem. > > True, but that case can only happen if servers are frozen before clients. > You don't need a full dependency graph. A simple set sequence of two > classes of tasks will do. Any replying to myself. A deadlock here is not fatal. You can and will timeout in the freezer and can try again. REegards Oliver