From nobody Wed Sep 10 11:03:51 2025 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 551F5C6FD18 for ; Tue, 25 Apr 2023 14:36:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234201AbjDYOgZ (ORCPT ); Tue, 25 Apr 2023 10:36:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45086 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233893AbjDYOgT (ORCPT ); Tue, 25 Apr 2023 10:36:19 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 2FB82BB8D for ; Tue, 25 Apr 2023 07:36:18 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id E715FC14; Tue, 25 Apr 2023 07:37:01 -0700 (PDT) Received: from localhost.localdomain (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 616723F587; Tue, 25 Apr 2023 07:36:16 -0700 (PDT) From: James Clark To: coresight@lists.linaro.org, quic_jinlmao@quicinc.com, mike.leach@linaro.org, suzuki.poulose@arm.com Cc: James Clark , Leo Yan , Alexander Shishkin , Greg Kroah-Hartman , Mathieu Poirier , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH v6 01/13] coresight: Fix loss of connection info when a module is unloaded Date: Tue, 25 Apr 2023 15:35:28 +0100 Message-Id: <20230425143542.2305069-2-james.clark@arm.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230425143542.2305069-1-james.clark@arm.com> References: <20230425143542.2305069-1-james.clark@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" 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 Reviewed-by: Mike Leach 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/hwtraci= ng/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 =3D=3D conn->child_fwnode) { iterator->orphan =3D 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 =3D NULL; + + conn->child_dev =3D NULL; /* No need to continue */ break; } --=20 2.34.1