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=-6.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_NEOMUTT 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 8D7CDC43387 for ; Thu, 10 Jan 2019 15:28:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5E06A20685 for ; Thu, 10 Jan 2019 15:28:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729688AbfAJP2z (ORCPT ); Thu, 10 Jan 2019 10:28:55 -0500 Received: from mail.bootlin.com ([62.4.15.54]:50459 "EHLO mail.bootlin.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729143AbfAJP2y (ORCPT ); Thu, 10 Jan 2019 10:28:54 -0500 Received: by mail.bootlin.com (Postfix, from userid 110) id 849A3209C2; Thu, 10 Jan 2019 16:28:51 +0100 (CET) Received: from localhost (aaubervilliers-681-1-45-241.w90-88.abo.wanadoo.fr [90.88.163.241]) by mail.bootlin.com (Postfix) with ESMTPSA id 50116209BC; Thu, 10 Jan 2019 16:28:51 +0100 (CET) Date: Thu, 10 Jan 2019 16:28:51 +0100 From: Maxime Ripard To: Chen-Yu Tsai Cc: Linus Walleij , linux-arm-kernel@lists.infradead.org, linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] pinctrl: sunxi: Fix and simplify pin bank regulator handling Message-ID: <20190110152851.g33mgpfgzeatj332@flea> References: <20190110082633.6321-1-wens@csie.org> <20190110082633.6321-2-wens@csie.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="2pnopejneh27lbcz" Content-Disposition: inline In-Reply-To: <20190110082633.6321-2-wens@csie.org> User-Agent: NeoMutt/20180716 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --2pnopejneh27lbcz Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Jan 10, 2019 at 04:26:33PM +0800, Chen-Yu Tsai wrote: > The new per-pin-bank regulator handling code in the sunxi pinctrl driver > has mismatched conditions for enabling and disabling the regulator: it > is enabled each time a pin is requested, but only disabled when the > pin-bank's reference count reaches zero. >=20 > Since we are doing reference counting already, there's no need to enable > the regulator each time a pin is requested. Instead we can just do it > for the first requested pin of each pin-bank. Thus we can reverse the > test and bail out early if it's not the first occurrence. >=20 > Fixes: 9a2a566adb00 ("pinctrl: sunxi: Deal with per-bank regulators") > Signed-off-by: Chen-Yu Tsai Acked-by: Maxime Ripard > I'm getting the feeling that the current code is prone to race > conditions when pinctrl sets are actively switched during runtime, or > gpios are requested and freed from userspace. >=20 > Any ideas? IIRC, I've looked into it when writing that patch and there's an upper mutex that prevents request from being called multiple times at once. Linus might prove me wrong though. Maxime --=20 Maxime Ripard, Bootlin Embedded Linux and Kernel engineering https://bootlin.com --2pnopejneh27lbcz Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQRcEzekXsqa64kGDp7j7w1vZxhRxQUCXDdkswAKCRDj7w1vZxhR xT4RAQDm0VrViQOqnAb+y4lxm/C2Kk6e0f9nii3jW/wt7IavcgEA2l2fHktJKyQS bjMr8bur8Y3On3zKYvDRU+a+LHjdEAc= =+NHo -----END PGP SIGNATURE----- --2pnopejneh27lbcz--