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 A38FDC433EF for ; Fri, 1 Jul 2022 08:33:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235942AbiGAIdw (ORCPT ); Fri, 1 Jul 2022 04:33:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39438 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235407AbiGAIdn (ORCPT ); Fri, 1 Jul 2022 04:33:43 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ADA4B677D3; Fri, 1 Jul 2022 01:33:42 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 1E606B82E4F; Fri, 1 Jul 2022 08:33:41 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5A961C341C6; Fri, 1 Jul 2022 08:33:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1656664419; bh=OvGAcIxhYOa5JbVDHlKxCT9h2qhKMwiLkryX0yjrQdM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Yj3f8GKfE/qs0EnDllsntBK0+g/GsTebNwxx69W+K1dpfRPxBQykrYEFzZC+4nHD3 7NrQRNiEHrMW3JHpsebD5zrI18nsjwbTanmZg9VDpUTPPZDA5PxZUUKaGDYTooD3tF XuCgiO7y1g4NBKY01xK9/F7QX1WeyexYqT5Mxnxc= Date: Fri, 1 Jul 2022 10:33:37 +0200 From: Greg Kroah-Hartman To: "Rafael J. Wysocki" Cc: Linux PM , LKML , Ulf Hansson , Peter Wang , Adrian Hunter , Saravana Kannan Subject: Re: [PATCH] PM: runtime: Fix supplier device management during consumer probe Message-ID: References: <4748074.GXAFRqVoOG@kreacher> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4748074.GXAFRqVoOG@kreacher> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 30, 2022 at 09:16:41PM +0200, Rafael J. Wysocki wrote: > From: Rafael J. Wysocki > > Because pm_runtime_get_suppliers() bumps up the rpm_active counter > of each device link to a supplier of the given device in addition > to bumping up the supplier's PM-runtime usage counter, a runtime > suspend of the consumer device may case the latter to go down to 0 > when pm_runtime_put_suppliers() is running on a remote CPU. If that > happens after pm_runtime_put_suppliers() has released power.lock for > the consumer device, and a runtime resume of that device takes place > immediately after it, before pm_runtime_put() is called for the > supplier, that pm_runtime_put() call may cause the supplier to be > suspended even though the consumer is active. > > To prevent that from happening, modify pm_runtime_get_suppliers() to > call pm_runtime_get_sync() for the given device's suppliers without > touching the rpm_active counters of the involved device links > Accordingly, modify pm_runtime_put_suppliers() to call pm_runtime_put() > for the given device's suppliers without looking at the rpm_active > counters of the device links at hand. [This is analogous to what > happened before commit 4c06c4e6cf63 ("driver core: Fix possible > supplier PM-usage counter imbalance").] > > Since pm_runtime_get_suppliers() sets supplier_preactivated for each > device link where the supplier's PM-runtime usage counter has been > incremented and pm_runtime_put_suppliers() calls pm_runtime_put() for > the suppliers whose device links have supplier_preactivated set, the > PM-runtime usage counter is balanced for each supplier and this is > independent of the runtime suspend and resume of the consumer device. > > However, in case a device link with DL_FLAG_PM_RUNTIME set is dropped > during the consumer device probe, so pm_runtime_get_suppliers() bumps > up the supplier's PM-runtime usage counter, but it cannot be dropped by > pm_runtime_put_suppliers(), make device_link_release_fn() take care of > that. > > Fixes: 4c06c4e6cf63 ("driver core: Fix possible supplier PM-usage counter imbalance") > Reported-by: Peter Wang > Signed-off-by: Rafael J. Wysocki > --- > drivers/base/core.c | 10 ++++++++++ > drivers/base/power/runtime.c | 14 +------------- > 2 files changed, 11 insertions(+), 13 deletions(-) Reviewed-by: Greg Kroah-Hartman