From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:38824 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933692AbeDKTDJ (ORCPT ); Wed, 11 Apr 2018 15:03:09 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mathieu Poirier , Robert Walker , Suzuki K Poulose , Sasha Levin Subject: [PATCH 4.9 230/310] coresight: Fix reference count for software sources Date: Wed, 11 Apr 2018 20:36:09 +0200 Message-Id: <20180411183632.403871237@linuxfoundation.org> In-Reply-To: <20180411183622.305902791@linuxfoundation.org> References: <20180411183622.305902791@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Suzuki K Poulose [ Upstream commit 022aa1a81b778789ee7cf3124595854276a0330d ] For software sources (i.e STM), there could be multiple agents generating the trace data, unlike the ETMs. So we need to properly do the accounting for the active number of users to disable the device when the last user goes away. Right now, the reference counting is broken for sources as we skip the actions when we detect that the source is enabled. This patch fixes the problem by adding the refcounting for software sources, even when they are enabled. Cc: Mathieu Poirier Reported-by: Robert Walker Signed-off-by: Suzuki K Poulose Signed-off-by: Mathieu Poirier Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/hwtracing/coresight/coresight.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) --- a/drivers/hwtracing/coresight/coresight.c +++ b/drivers/hwtracing/coresight/coresight.c @@ -498,6 +498,9 @@ int coresight_enable(struct coresight_de { int cpu, ret = 0; struct list_head *path; + enum coresight_dev_subtype_source subtype; + + subtype = csdev->subtype.source_subtype; mutex_lock(&coresight_mutex); @@ -505,8 +508,16 @@ int coresight_enable(struct coresight_de if (ret) goto out; - if (csdev->enable) + if (csdev->enable) { + /* + * There could be multiple applications driving the software + * source. So keep the refcount for each such user when the + * source is already enabled. + */ + if (subtype == CORESIGHT_DEV_SUBTYPE_SOURCE_SOFTWARE) + atomic_inc(csdev->refcnt); goto out; + } path = coresight_build_path(csdev); if (IS_ERR(path)) { @@ -523,7 +534,7 @@ int coresight_enable(struct coresight_de if (ret) goto err_source; - switch (csdev->subtype.source_subtype) { + switch (subtype) { case CORESIGHT_DEV_SUBTYPE_SOURCE_PROC: /* * When working from sysFS it is important to keep track