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=-8.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 A38D1C2BA19 for ; Tue, 14 Apr 2020 15:16:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7680C20768 for ; Tue, 14 Apr 2020 15:16:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=mg.codeaurora.org header.i=@mg.codeaurora.org header.b="rUyVQqrg" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2438022AbgDNPQa (ORCPT ); Tue, 14 Apr 2020 11:16:30 -0400 Received: from mail27.static.mailgun.info ([104.130.122.27]:20387 "EHLO mail27.static.mailgun.info" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2407252AbgDNPF4 (ORCPT ); Tue, 14 Apr 2020 11:05:56 -0400 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1586876755; h=Content-Transfer-Encoding: Content-Type: In-Reply-To: MIME-Version: Date: Message-ID: From: References: Cc: To: Subject: Sender; bh=2sHXwJ8AdtS+pVXjlc3JcGuGpLLjSecwst28kNFXaDE=; b=rUyVQqrgk8Ms5DInHRGa59N4XnzEwiTKkrsU+zwJN6aRTddQWF71Ndfh3gLXB5oFMv7dH6X7 FgK78pwxODIrEo7cDHCzvhGpihUrjOWKRdJwlKA3fbebnfYDxLmGB44YRVrPVrrNh0Yg/6tx zKWHwTP5WHwGkuqzNP14NuXGP3Q= X-Mailgun-Sending-Ip: 104.130.122.27 X-Mailgun-Sid: WyI0MWYwYSIsICJsaW51eC1rZXJuZWxAdmdlci5rZXJuZWwub3JnIiwgImJlOWU0YSJd Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by mxa.mailgun.org with ESMTP id 5e95d13b.7fadc8ad0810-smtp-out-n05; Tue, 14 Apr 2020 15:05:31 -0000 (UTC) Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 6422BC44788; Tue, 14 Apr 2020 15:05:31 +0000 (UTC) Received: from [10.111.193.245] (blr-bdr-fw-01_GlobalNAT_AllZones-Outside.qualcomm.com [103.229.18.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: rnayak) by smtp.codeaurora.org (Postfix) with ESMTPSA id EC3EAC494AA; Tue, 14 Apr 2020 15:05:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org EC3EAC494AA Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; spf=none smtp.mailfrom=rnayak@codeaurora.org Subject: Re: [RFC] opp: Fixup release of clock when using set/put clkname To: Viresh Kumar Cc: sboyd@kernel.org, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org References: <1586848508-1320-1-git-send-email-rnayak@codeaurora.org> <20200414071823.jdhkprtkizyeua23@vireshk-i7> From: Rajendra Nayak Message-ID: <83c523d0-e18e-0401-5456-2dbba524ee98@codeaurora.org> Date: Tue, 14 Apr 2020 20:35:26 +0530 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <20200414071823.jdhkprtkizyeua23@vireshk-i7> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/14/2020 12:48 PM, Viresh Kumar wrote: > On 14-04-20, 12:45, Rajendra Nayak wrote: >> Fixup dev_pm_opp_put_clkname() to check for a valid clock pointer >> before it does a clk_put, since its likely that >> _opp_table_kref_release() has already done a clk_put. Also fixup > > kref release is the last thing that happens on the table, it can't get > called after dev_pm_opp_put_clkname(). so in cases where I do have an OPP table for a device in DT and I do dev_pm_opp_set_clkname() dev_pm_opp_of_add_table() and clean it up with a dev_pm_opp_of_remove_table() dev_pm_opp_put_clkname() things seem to work fine as expected. However, given I call these unconditionally in common drivers and on some (old) platforms we really don't have an OPP table (only scale clocks) things get a little tricky. So looks like the ref counting in such cases gets messed up, and we end up with dev_pm_opp_of_remove_table() calling _opp_table_kref_release() and releasing the clock, and then the subsequent call to dev_pm_opp_put_clkname() crashes. >> _opp_table_kref_release() to set the clock pointer to ERR_PTR(-EINVAL) >> after its done doing a clk_put so dev_pm_opp_put_clkname() can then >> catch it. >> >> Signed-off-by: Rajendra Nayak >> --- >> drivers/opp/core.c | 10 +++++++--- >> 1 file changed, 7 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/opp/core.c b/drivers/opp/core.c >> index e4f01e7..6d064a8 100644 >> --- a/drivers/opp/core.c >> +++ b/drivers/opp/core.c >> @@ -1061,8 +1061,10 @@ static void _opp_table_kref_release(struct kref *kref) >> _of_clear_opp_table(opp_table); >> >> /* Release clk */ >> - if (!IS_ERR(opp_table->clk)) >> + if (!IS_ERR(opp_table->clk)) { >> clk_put(opp_table->clk); >> + opp_table->clk = ERR_PTR(-EINVAL); >> + } >> >> WARN_ON(!list_empty(&opp_table->opp_list)); >> >> @@ -1744,8 +1746,10 @@ void dev_pm_opp_put_clkname(struct opp_table *opp_table) >> /* Make sure there are no concurrent readers while updating opp_table */ >> WARN_ON(!list_empty(&opp_table->opp_list)); >> >> - clk_put(opp_table->clk); >> - opp_table->clk = ERR_PTR(-EINVAL); >> + if (!IS_ERR(opp_table->clk)) { >> + clk_put(opp_table->clk); >> + opp_table->clk = ERR_PTR(-EINVAL); >> + } >> >> dev_pm_opp_put_opp_table(opp_table); >> } >> -- >> QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member >> of Code Aurora Forum, hosted by The Linux Foundation > -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation