From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 72D13C43441 for ; Mon, 19 Nov 2018 15:28:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3A837206BB for ; Mon, 19 Nov 2018 15:28:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=lunn.ch header.i=@lunn.ch header.b="KIAf2P88" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3A837206BB Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lunn.ch Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729860AbeKTBw3 (ORCPT ); Mon, 19 Nov 2018 20:52:29 -0500 Received: from vps0.lunn.ch ([185.16.172.187]:40609 "EHLO vps0.lunn.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729746AbeKTBw3 (ORCPT ); Mon, 19 Nov 2018 20:52:29 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lunn.ch; s=20171124; h=In-Reply-To:Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date; bh=CgSBa2lOOWltF0vvpytwhnaY/O6GLg6OyNRbAYC/q90=; b=KIAf2P88fbDaFwJsDABF85Rw1tDmNPrYd7zpawDgrgPznldH9ZO70COPXGKsKzKO0Av1VzqBawhQE+uO4GdJl1AtiYli5Di3nZbPxsygOnEP2+rpPrm+dUCWFXblxJJVmHqtwO6ZBGgkGQbqTT0WvDHa3OA1pFal/Lu66pVRcOU=; Received: from andrew by vps0.lunn.ch with local (Exim 4.84_2) (envelope-from ) id 1gOlTS-0007n1-6r; Mon, 19 Nov 2018 16:28:30 +0100 Date: Mon, 19 Nov 2018 16:28:30 +0100 From: Andrew Lunn To: Andreas Schwab Cc: Quentin Schulz , davem@davemloft.net, f.fainelli@gmail.com, allan.nielsen@microchip.com, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, thomas.petazzoni@bootlin.com, alexandre.belloni@bootlin.com, linux-riscv@lists.infradead.org Subject: Re: [PATCH net-next v3 1/6] net: phy: mscc: migrate to phy_select/restore_page functions Message-ID: <20181119152830.GE26852@lunn.ch> References: <20181008100728.24959-1-quentin.schulz@bootlin.com> <20181008100728.24959-2-quentin.schulz@bootlin.com> <20181119151057.GC26852@lunn.ch> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 19, 2018 at 04:13:10PM +0100, Andreas Schwab wrote: > On Nov 19 2018, Andrew Lunn wrote: > > > On Mon, Nov 19, 2018 at 03:57:17PM +0100, Andreas Schwab wrote: > >> On Okt 08 2018, Quentin Schulz wrote: > >> > >> > The Microsemi PHYs have multiple banks of registers (called pages). > >> > Registers can only be accessed from one page, if we need a register from > >> > another page, we need to switch the page and the registers of all other > >> > pages are not accessible anymore. > >> > > >> > Basically, to read register 5 from page 0, 1, 2, etc., you do the same > >> > phy_read(phydev, 5); but you need to set the desired page beforehand. > >> > > >> > In order to guarantee that two concurrent functions do not change the > >> > page, we need to do some locking per page. This can be achieved with the > >> > use of phy_select_page and phy_restore_page functions but phy_write/read > >> > calls in-between those two functions shall be replaced by their > >> > lock-free alternative __phy_write/read. > >> > > >> > Let's migrate this driver to those functions. > >> > >> This has some serious locking problem. > > > > Hi Andreas > > > > Could you be more specific. Are you getting a deadlock? A WARN_ON? > > See the stack trace. That's where it hangs. So you never said it hangs. The stacktrace helps, but a description of what actually happens also helps. And i expect Quentin has booted this code lots of times and not had a hang. So some hits how to reproduce it would also help. Maybe your kernel config? I'm interested because he is using the core mdio locking primitives. If those are broken, i want to know. Thanks Andrew