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[2620:137:e000::1:20]) by mx.google.com with ESMTP id p184-20020a625bc1000000b006293f8330fcsi15896570pfb.322.2023.04.12.06.13.04; Wed, 12 Apr 2023 06:13:17 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=fZEKcEqQ; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230325AbjDLNMs (ORCPT + 99 others); Wed, 12 Apr 2023 09:12:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35100 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230182AbjDLNMl (ORCPT ); Wed, 12 Apr 2023 09:12:41 -0400 Received: from mail-pj1-x1033.google.com (mail-pj1-x1033.google.com [IPv6:2607:f8b0:4864:20::1033]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8BA077DA8 for ; Wed, 12 Apr 2023 06:12:20 -0700 (PDT) Received: by mail-pj1-x1033.google.com with SMTP id v9so16762740pjk.0 for ; Wed, 12 Apr 2023 06:12:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1681305139; x=1683897139; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=D0hP3jv/htpFn6noooEWQxBH2VirSMKKiLKRhrd4CVQ=; b=fZEKcEqQe/+CzECq7x8VyAs7MJhvwLRndGyF7cG0pmc00tX1LdoME0zIIdPDsvy7Rl aVhZ1fvndJuiHUJLvPrvV9tW0Wqk7iU611OxZI7S5DSEIA/D4WVLVLUVyb/J5oVrKbUn KidNfSwDklp1sz5DHvQ3D9yMNEClqJFRhETNQ+FUVCl3Okr+KD9fruNFmdwqIMrQ089S OHybyntxkI3zNcWBWNduFlj5QkLw0LdrnAEUOXTE50k0Y8Wpvc0D7xSRql/zlOXyt6Kf J4uAfDRTWwSNZ0D6He50GQjnF+bW6K0cLqa/eH4l4jTHV1UeAqLoji2F/m69lVeLUfH6 um0A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1681305139; x=1683897139; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=D0hP3jv/htpFn6noooEWQxBH2VirSMKKiLKRhrd4CVQ=; b=MJf7yf1gHGlp2m0bw/F7AZ/qfA7DLQ7Zyuz+Ejm+T5SkrZNDt8pWFTPF6AyGWtL4DI T/8KFzCvfQaJctg8SVr4IsatvsenY1409WKgHdHx3LQwblea4YlISEqlUUBifIhuskqZ YidNfx4IPWFHBaKUAmLZPMvIUyeuhDWHrCNqKR4Q843Dh+KN3b2CdUkakcbusBX7ByVp 5cjg2P1J61WSHGHBFtl1dRj0mw2K2M2TWFtrkbqo3lZeXRunziYUgDFuQEu0GZAJUuWa JIhLVGUQYpEOb9jaDA3Zwkmc/EZGkYewoA/4yexGcstNSjspdosCinX6bfx+Eglcd7fp JgVQ== X-Gm-Message-State: AAQBX9eJ48qSzzYHXhD47uKMozfNy+UvkoCUTfsd3aa1IPER8OaJ2QJa 8k/6wLtw44ZNyg5T5xuYdh3cfbbE7wjwppT7Hu+OeQ== X-Received: by 2002:a17:903:22ca:b0:1a4:f282:91c7 with SMTP id y10-20020a17090322ca00b001a4f28291c7mr4899727plg.6.1681305139610; Wed, 12 Apr 2023 06:12:19 -0700 (PDT) MIME-Version: 1.0 References: <20230404155121.1824126-1-james.clark@arm.com> <20230404155121.1824126-2-james.clark@arm.com> In-Reply-To: <20230404155121.1824126-2-james.clark@arm.com> From: Mike Leach Date: Wed, 12 Apr 2023 14:12:08 +0100 Message-ID: Subject: Re: [PATCH v5 01/13] coresight: Fix loss of connection info when a module is unloaded To: James Clark Cc: coresight@lists.linaro.org, quic_jinlmao@quicinc.com, suzuki.poulose@arm.com, Mathieu Poirier , Leo Yan , Alexander Shishkin , Greg Kroah-Hartman , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 4 Apr 2023 at 16:51, James Clark wrote: > > child_fwnode should be a read only property based on the DT or ACPI. If > it's cleared on the parent device when a child is unloaded, then when > the child is loaded again the connection won't be remade. > > child_dev should be cleared instead which signifies that the connection > should be remade when the child_fwnode registers a new coresight_device. > > Similarly the reference count shouldn't be decremented as long as the > parent device exists. The correct place to drop the reference is in > coresight_release_platform_data() which is already done. > > Reproducible on Juno with the following steps: > > # load all coresight modules. > $ cd /sys/bus/coresight/devices/ > $ echo 1 > tmc_etr0/enable_sink > $ echo 1 > etm0/enable_source > # Works fine ^ > > $ echo 0 > etm0/enable_source > $ rmmod coresight-funnel > $ modprobe coresight-funnel > $ echo 1 > etm0/enable_source > -bash: echo: write error: Invalid argument > > Fixes: 37ea1ffddffa ("coresight: Use fwnode handle instead of device names") > Fixes: 2af89ebacf29 ("coresight: Clear the connection field properly") > Tested-by: Suzuki K Poulose > Signed-off-by: James Clark > --- > drivers/hwtracing/coresight/coresight-core.c | 9 ++------- > 1 file changed, 2 insertions(+), 7 deletions(-) > > diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c > index d3bf82c0de1d..5733294ce5cd 100644 > --- a/drivers/hwtracing/coresight/coresight-core.c > +++ b/drivers/hwtracing/coresight/coresight-core.c > @@ -1419,13 +1419,8 @@ static int coresight_remove_match(struct device *dev, void *data) > if (csdev->dev.fwnode == conn->child_fwnode) { > iterator->orphan = true; > coresight_remove_links(iterator, conn); > - /* > - * Drop the reference to the handle for the remote > - * device acquired in parsing the connections from > - * platform data. > - */ > - fwnode_handle_put(conn->child_fwnode); > - conn->child_fwnode = NULL; > + > + conn->child_dev = NULL; > /* No need to continue */ > break; > } > -- > 2.34.1 > Reviewed-by: Mike Leach -- Mike Leach Principal Engineer, ARM Ltd. Manchester Design Centre. UK