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=-11.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 0A103C433DF for ; Sat, 25 Jul 2020 10:17:34 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id C404A206D7 for ; Sat, 25 Jul 2020 10:17:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="0xW1QtGC"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=mg.codeaurora.org header.i=@mg.codeaurora.org header.b="t79nmD2U" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C404A206D7 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=Ax/hYsrVw9Iq4jZOIG+ucmcqu6WlRP2RUT3xDGCQzOQ=; b=0xW1QtGC7L2XGWxBKgF0CPDNr NRZNRgem2IUZYOwEMPxNs3R5Y/U2hzBWV8ONWr1yU7WAKn//ZATRH1WuHwyntaWdkcyahkRlKAj33 jt5oTDet5N4foLyEwpajEMyvYBXCe/Xh/UNGCjViv87Fr4vXrDYxZJzGwwQWtcRQxw/dcyKAkXRvD XpuKqAuPfjzz/ipAqyX+Up5ZI3St1iEqQbu8lVMItZKM0gn8NKEE1/RAwT/EfYEv0gJmGh3MuvJmc yc0aaDJiISkSZ1x2MqoHREmYQN8h0YzbzbDOHLE+H8cpBoIbGXtcvs+0p2SvECidM0a/TEVEWLpZk 4jrsHFZTw==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jzHDd-0006zx-V6; Sat, 25 Jul 2020 10:15:53 +0000 Received: from m43-7.mailgun.net ([69.72.43.7]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jzHDY-0006zb-Pk for linux-arm-kernel@lists.infradead.org; Sat, 25 Jul 2020 10:15:52 +0000 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1595672151; h=In-Reply-To: Content-Type: MIME-Version: References: Message-ID: Subject: Cc: To: From: Date: Sender; bh=NIEwslEsEryWaVqNqa23oEbcbuibdTYQIaKIe4XSOuo=; b=t79nmD2UQlCw/V0IlkwH1h8BeBkat0VKpm/wvQTn3eRAElb5cyA1nPS9+YD2kUPdMhTZH9c1 3SbWOsyavM3OfjaNg2FV++xrZaR2BfOA/RnX078qP4yi4VAAgGXvbxRtbezBMhHNSqj8QO9Q ZHWcO7C5H/RCMyPN6XQxXkI4FXk= X-Mailgun-Sending-Ip: 69.72.43.7 X-Mailgun-Sid: WyJiYzAxZiIsICJsaW51eC1hcm0ta2VybmVsQGxpc3RzLmluZnJhZGVhZC5vcmciLCAiYmU5ZTRhIl0= Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n13.prod.us-east-1.postgun.com with SMTP id 5f1c03eafcbecb3df1492c0d (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Sat, 25 Jul 2020 10:05:30 GMT Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 36C31C43395; Sat, 25 Jul 2020 10:05:29 +0000 (UTC) Received: from codeaurora.org (unknown [180.166.53.21]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: tingwei) by smtp.codeaurora.org (Postfix) with ESMTPSA id DD6C4C433C9; Sat, 25 Jul 2020 10:05:24 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org DD6C4C433C9 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=tingweiz@codeaurora.org Date: Sat, 25 Jul 2020 18:05:16 +0800 From: Tingwei Zhang To: Mike Leach Subject: Re: [PATCH v4 06/20] coresight: add try_get_module() in coresight_grab_device() Message-ID: <20200725100516.GA18120@codeaurora.org> References: <20200723042802.22511-1-tingwei@codeaurora.org> <20200723042802.22511-7-tingwei@codeaurora.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200725_061551_677403_69EBD099 X-CRM114-Status: GOOD ( 33.09 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: tsoni@codeaurora.org, Sai Prakash Ranjan , Kim Phillips , Mathieu Poirier , Suzuki K Poulose , Alexander Shishkin , Greg Kroah-Hartman , Coresight ML , Randy Dunlap , Mian Yousaf Kaukab , Russell King , Mao Jinlong , Tingwei Zhang , Leo Yan , linux-arm-kernel Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Mike, Thu, Jul 23, 2020 at 06:55:47PM +0800, Mike Leach wrote: > Hi Tingwei, > > On Thu, 23 Jul 2020 at 05:28, Tingwei Zhang > wrote: > > > > When coresight device is in an active session, driver module of > > that device should not be removed. Use try_get_module() in > > coresight_grab_device() to prevent module to be unloaded. > > > > Signed-off-by: Tingwei Zhang > > --- > > drivers/hwtracing/coresight/coresight.c | 27 +++++++++++++++++++++---- > > 1 file changed, 23 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/hwtracing/coresight/coresight.c > b/drivers/hwtracing/coresight/coresight.c > > index b7151c5f81b1..17bc76ea86ae 100644 > > --- a/drivers/hwtracing/coresight/coresight.c > > +++ b/drivers/hwtracing/coresight/coresight.c > > @@ -640,7 +640,7 @@ struct coresight_device > *coresight_get_sink_by_id(u32 id) > > * don't appear on the trace path, they should be handled along with > the > > * the master device. > > */ > > -static void coresight_grab_device(struct coresight_device *csdev) > > +static int coresight_grab_device(struct coresight_device *csdev) > > { > > int i; > > > > @@ -648,10 +648,25 @@ static void coresight_grab_device(struct > coresight_device *csdev) > > struct coresight_device *child; > > > > child = csdev->pdata->conns[i].child_dev; > > - if (child && child->type == CORESIGHT_DEV_TYPE_HELPER) > > + if (child && child->type == CORESIGHT_DEV_TYPE_HELPER) { > > + if > (!try_module_get(child->dev.parent->driver->owner)) > > + goto err; > > pm_runtime_get_sync(child->dev.parent); > > + } > > } > > + if (!try_module_get(csdev->dev.parent->driver->owner)) > > + goto err; > > pm_runtime_get_sync(csdev->dev.parent); > > + return 0; > > +err: > > + for (i--; i >= 0; i--) { > > + struct coresight_device *child; > > + > > + child = csdev->pdata->conns[i].child_dev; > > + if (child && child->type == CORESIGHT_DEV_TYPE_HELPER) > > + pm_runtime_put(child->dev.parent); > > + } > > + return -ENODEV; > > } > > > > /* > > @@ -663,12 +678,15 @@ static void coresight_drop_device(struct > coresight_device *csdev) > > int i; > > > > pm_runtime_put(csdev->dev.parent); > > + module_put(csdev->dev.parent->driver->owner); > > for (i = 0; i < csdev->pdata->nr_outport; i++) { > > struct coresight_device *child; > > > > child = csdev->pdata->conns[i].child_dev; > > - if (child && child->type == CORESIGHT_DEV_TYPE_HELPER) > > + if (child && child->type == CORESIGHT_DEV_TYPE_HELPER) { > > pm_runtime_put(child->dev.parent); > > + module_put(child->dev.parent->driver->owner); > > + } > > } > > } > > > > @@ -721,7 +739,8 @@ static int _coresight_build_path(struct > coresight_device *csdev, > > if (!node) > > return -ENOMEM; > > > > - coresight_grab_device(csdev); > > + if (coresight_grab_device(csdev)) > > + return -ENODEV; > > node->csdev = csdev; > > list_add(&node->link, path); > > > > -- > > The Qualcomm Innovation Center, Inc. is a member of the Code Aurora > Forum, > > a Linux Foundation Collaborative Project > > > > The CTI devices are associated with other coresight components using > csdev->ect_dev; These are not handled in the main linear trace path as > these have a star topology interlinking all components. > However, when a component has an associated ect_dev then is enabled at > the same time as the other component is enabled. > > So a module_get/put will be needed for this association to prevent the > CTI being removed while a trace session is active. > I suggest in coresight.c : coresight_control_assoc_ectdev() > In module unload process, devices of that module will be removed. In this case, cti_remove() is called on all cti device when unloading cti module. All cti connections is cleaned at that time. csdev->ect_dev is set to NULL. coresight_control_assoc_ectdev() will return since since ect_csdev is NULL. I think we are safe without holding module reference since cti driver has done a pretty good job on clean up. Let me know if you still think we need hold the module reference. Thanks, Tingwei > Regards > > Mike > > > -- > Mike Leach > Principal Engineer, ARM Ltd. > Manchester Design Centre. UK > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel