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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 29D05CCA47E for ; Thu, 16 Jun 2022 15:31:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1377958AbiFPPbQ (ORCPT ); Thu, 16 Jun 2022 11:31:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40394 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237941AbiFPPbG (ORCPT ); Thu, 16 Jun 2022 11:31:06 -0400 Received: from metis.ext.pengutronix.de (metis.ext.pengutronix.de [IPv6:2001:67c:670:201:290:27ff:fe1d:cc33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4576440E6F for ; Thu, 16 Jun 2022 08:31:06 -0700 (PDT) Received: from ptx.hi.pengutronix.de ([2001:67c:670:100:1d::c0]) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1o1rSU-0003NM-3h; Thu, 16 Jun 2022 17:30:58 +0200 Received: from ore by ptx.hi.pengutronix.de with local (Exim 4.92) (envelope-from ) id 1o1rST-00069W-IS; Thu, 16 Jun 2022 17:30:57 +0200 Date: Thu, 16 Jun 2022 17:30:57 +0200 From: Oleksij Rempel To: Andrew Lunn Cc: Vivien Didelot , Florian Fainelli , Vladimir Oltean , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , kernel@pengutronix.de, linux-kernel@vger.kernel.org, netdev@vger.kernel.org Subject: Re: [PATCH net-next v1 1/1] net: dsa: ar9331: fix potential dead lock on mdio access Message-ID: <20220616153057.GB28995@pengutronix.de> References: <20220616112550.877118-1-o.rempel@pengutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: X-Sent-From: Pengutronix Hildesheim X-URL: http://www.pengutronix.de/ X-Accept-Language: de,en X-Accept-Content-Type: text/plain User-Agent: Mutt/1.10.1 (2018-07-13) X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::c0 X-SA-Exim-Mail-From: ore@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 16, 2022 at 03:34:18PM +0200, Andrew Lunn wrote: > > static int ar9331_mdio_read(void *ctx, const void *reg_buf, size_t reg_len, > > @@ -849,6 +849,8 @@ static int ar9331_mdio_read(void *ctx, const void *reg_buf, size_t reg_len, > > return 0; > > } > > > > + mutex_lock_nested(&sbus->mdio_lock, MDIO_MUTEX_NESTED); > > + > > Do you know about mdiobus_read_nested() and > mdiobus_write_nested(). The mv88e6xxx driver uses these. Yes. I need at least 2 master MDIO accesses to implement 1 slave mdio access. So I decided to get lock one time for all needed accesses instead of taking it multiple times. Regards, Oleksij -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |