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 0EF86C4332F for ; Wed, 9 Mar 2022 02:57:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231558AbiCIC6S (ORCPT ); Tue, 8 Mar 2022 21:58:18 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57260 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231533AbiCIC6R (ORCPT ); Tue, 8 Mar 2022 21:58:17 -0500 Received: from alexa-out-sd-01.qualcomm.com (alexa-out-sd-01.qualcomm.com [199.106.114.38]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 35F23122226; Tue, 8 Mar 2022 18:57:16 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=quicinc.com; i=@quicinc.com; q=dns/txt; s=qcdkim; t=1646794636; x=1678330636; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=/6orijhYB1/V+Qoz6qfONCjhMSnQhyh2RiYXK66WPPc=; b=LHH5ySt5zoPQikci6eCc2m39RLCRjZt4efk7ZgtsvwiF9NIZkiR0wvBU jzl10xyBwIZ5dIHe0s6aLoVCAcCr6MZs6th0je7ESF9V2tTuiT8d5TgSh SWnGaX0Jrz1ctVpmG5r3uTXQF2Vmgt9g8LepAi+EupD2GapVgEhhVk87s Y=; Received: from unknown (HELO ironmsg-SD-alpha.qualcomm.com) ([10.53.140.30]) by alexa-out-sd-01.qualcomm.com with ESMTP; 08 Mar 2022 18:57:15 -0800 X-QCInternal: smtphost Received: from nasanex01c.na.qualcomm.com ([10.47.97.222]) by ironmsg-SD-alpha.qualcomm.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Mar 2022 18:57:15 -0800 Received: from nalasex01a.na.qualcomm.com (10.47.209.196) by nasanex01c.na.qualcomm.com (10.47.97.222) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.15; Tue, 8 Mar 2022 18:57:15 -0800 Received: from [10.239.133.9] (10.80.80.8) by nalasex01a.na.qualcomm.com (10.47.209.196) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.15; Tue, 8 Mar 2022 18:57:11 -0800 Message-ID: <7db54684-2637-ba82-7146-c8a559337933@quicinc.com> Date: Wed, 9 Mar 2022 10:57:08 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.5.1 Subject: Re: [PATCH v2] coresight: core: Fix coresight device probe failure issue Content-Language: en-US To: Suzuki K Poulose , Mathieu Poirier , Mike Leach , Leo Yan , Alexander Shishkin CC: , , , , "Tingwei Zhang" , Yuanfang Zhang , Tao Zhang , Hao Zhang References: <20220304082350.30069-1-quic_jinlmao@quicinc.com> From: Jinlong Mao In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.80.80.8] X-ClientProxiedBy: nasanex01b.na.qualcomm.com (10.46.141.250) To nalasex01a.na.qualcomm.com (10.47.209.196) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Suzuki, On 3/8/2022 9:36 PM, Suzuki K Poulose wrote: > On 08/03/2022 11:56, Suzuki K Poulose wrote: >> Hi Jinlong >> >> On 04/03/2022 08:23, Mao Jinlong wrote: >>> It is possibe that probe failure issue happens when the device >>> and its child_device's probe happens at the same time. >>> In coresight_make_links, has_conns_grp is true for parent, but >>> has_conns_grp is false for child device as has_conns_grp is set >>> to true in coresight_create_conns_sysfs_group. The probe of parent >>> device will fail at this condition. Add has_conns_grp check for >>> child device before make the links and make the process from >>> device_register to connection_create be atomic to avoid this >>> probe failure issue. >>> >>> Suggested-by: Suzuki K Poulose >>> Suggested-by: Mike Leach >>> Signed-off-by: Mao Jinlong >>> --- >>>   drivers/hwtracing/coresight/coresight-core.c | 12 ++++++------ >>>   1 file changed, 6 insertions(+), 6 deletions(-) >>> >>> diff --git a/drivers/hwtracing/coresight/coresight-core.c >>> b/drivers/hwtracing/coresight/coresight-core.c >>> index 88653d1c06a4..b3e3bc59c09b 100644 >>> --- a/drivers/hwtracing/coresight/coresight-core.c >>> +++ b/drivers/hwtracing/coresight/coresight-core.c >>> @@ -1382,7 +1382,7 @@ static int coresight_fixup_device_conns(struct >>> coresight_device *csdev) >>>               continue; >>>           conn->child_dev = >>> coresight_find_csdev_by_fwnode(conn->child_fwnode); >>> -        if (conn->child_dev) { >>> +        if (conn->child_dev && conn->child_dev->has_conns_grp) { >>>               ret = coresight_make_links(csdev, conn, >>>                              conn->child_dev); >>>               if (ret) >>> @@ -1594,7 +1594,8 @@ struct coresight_device >>> *coresight_register(struct coresight_desc *desc) >>>       refcnts = kcalloc(nr_refcnts, sizeof(*refcnts), GFP_KERNEL); >>>       if (!refcnts) { >>>           ret = -ENOMEM; >>> -        goto err_free_csdev; >>> +        kfree(csdev); >>> +        goto err_out; >>>       } >>>       csdev->refcnt = refcnts; >>> @@ -1619,8 +1620,10 @@ struct coresight_device >>> *coresight_register(struct coresight_desc *desc) >>>       csdev->dev.fwnode = fwnode_handle_get(dev_fwnode(desc->dev)); >>>       dev_set_name(&csdev->dev, "%s", desc->name); >>> +    mutex_lock(&coresight_mutex); >>>       ret = device_register(&csdev->dev); >>>       if (ret) { >>> +        mutex_unlock(&coresight_mutex); >>>           put_device(&csdev->dev); >>>           /* >>>            * All resources are free'd explicitly via >>> @@ -1634,6 +1637,7 @@ struct coresight_device >>> *coresight_register(struct coresight_desc *desc) >>>           ret = etm_perf_add_symlink_sink(csdev); >>>           if (ret) { >>> +            mutex_unlock(&coresight_mutex); >>>               device_unregister(&csdev->dev); >>>               /* >>>                * As with the above, all resources are free'd >>> @@ -1645,8 +1649,6 @@ struct coresight_device >>> *coresight_register(struct coresight_desc *desc) >>>           } >>>       } >>> -    mutex_lock(&coresight_mutex); >>> - >>>       ret = coresight_create_conns_sysfs_group(csdev); >>>       if (!ret) >>>           ret = coresight_fixup_device_conns(csdev); >>> @@ -1663,8 +1665,6 @@ struct coresight_device >>> *coresight_register(struct coresight_desc *desc) >>>       return csdev; >>> -err_free_csdev: >>> -    kfree(csdev); >>>   err_out: >>>       /* Cleanup the connection information */ >>>       coresight_release_platform_data(NULL, desc->pdata); >> >> Could we consolidate the unlock sequence to a single point with >> something like this (untested): >> >> >> diff --git a/drivers/hwtracing/coresight/coresight-core.c >> b/drivers/hwtracing/coresight/coresight-core.c >> index af00dca8d1ac..198ee140c6e6 100644 >> --- a/drivers/hwtracing/coresight/coresight-core.c >> +++ b/drivers/hwtracing/coresight/coresight-core.c >> @@ -1571,6 +1571,7 @@ struct coresight_device >> *coresight_register(struct coresight_desc *desc) >>       int nr_refcnts = 1; >>       atomic_t *refcnts = NULL; >>       struct coresight_device *csdev; >> +    bool registered = false; >> >>       csdev = kzalloc(sizeof(*csdev), GFP_KERNEL); >>       if (!csdev) { >> @@ -1591,7 +1592,8 @@ struct coresight_device >> *coresight_register(struct coresight_desc *desc) >>       refcnts = kcalloc(nr_refcnts, sizeof(*refcnts), GFP_KERNEL); >>       if (!refcnts) { >>           ret = -ENOMEM; >> -        goto err_free_csdev; >> +        kfree(csdev); >> +        goto err_out; >>       } >> >>       csdev->refcnt = refcnts; >> @@ -1616,6 +1618,13 @@ struct coresight_device >> *coresight_register(struct coresight_desc *desc) >>       csdev->dev.fwnode = fwnode_handle_get(dev_fwnode(desc->dev)); >>       dev_set_name(&csdev->dev, "%s", desc->name); >> >> +    /* >> +     * Make sure the device registration and the connection fixup >> +     * are synchronised, so that we don't see uninitialised devices >> +     * on the coresight bus while trying to resolve the connections. >> +     */ >> +    mutex_lock(&coresight_mutex); >> + >>       ret = device_register(&csdev->dev); >>       if (ret) { >>           put_device(&csdev->dev); >> @@ -1623,7 +1632,7 @@ struct coresight_device >> *coresight_register(struct coresight_desc *desc) >>            * All resources are free'd explicitly via >>            * coresight_device_release(), triggered from put_device(). >>            */ >> -        goto err_out; >> +        goto out_unlock; >>       } >> >>       if (csdev->type == CORESIGHT_DEV_TYPE_SINK || >> @@ -1638,11 +1647,11 @@ struct coresight_device >> *coresight_register(struct coresight_desc *desc) >>                * from put_device(), which is in turn called from >>                * function device_unregister(). >>                */ >> -            goto err_out; >> +            goto out_unlock; >>           } >>       } >> - >> -    mutex_lock(&coresight_mutex); >> +    /* Device is now registered */ >> +    registered = true; >> >>       ret = coresight_create_conns_sysfs_group(csdev); >>       if (!ret) >> @@ -1652,16 +1661,15 @@ struct coresight_device >> *coresight_register(struct coresight_desc *desc) >>       if (!ret && cti_assoc_ops && cti_assoc_ops->add) >>           cti_assoc_ops->add(csdev); >> >> +out_unlock: >>       mutex_unlock(&coresight_mutex); >> -    if (ret) { >> +    /* Success */ >> +    if (!ret) >> +        return csdev; >> + >> +    /* Unregister the device if needed */ >> +    if (registered) >>           coresight_unregister(csdev); >> -        return ERR_PTR(ret); >> -    } > > Apologies, this should be preserved : > > i.e, >     if (registered) { >         coresight_unregister(csdev); >         return ERR_PTR(ret); >     } I will test with your changes and get back to you later. Thanks Jinlong Mao > > Thanks > Suzuki