linux-kernel - [PATCH v2 3/8] coresight: Protect unregistration with mutex

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Message-Id: <20260126-arm_coresight_refactor_dev_register-v2-3-b5a3c0441c15@arm.com>
Date: Mon, 26 Jan 2026 13:52:03 +0000
From: Leo Yan <leo.yan@....com>
To: Suzuki K Poulose <suzuki.poulose@....com>, 
 Mike Leach <mike.leach@...aro.org>, James Clark <james.clark@...aro.org>, 
 Alexander Shishkin <alexander.shishkin@...ux.intel.com>, 
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
 Mathieu Poirier <mathieu.poirier@...aro.org>, 
 Mao Jinlong <quic_jinlmao@...cinc.com>
Cc: coresight@...ts.linaro.org, linux-arm-kernel@...ts.infradead.org, 
 linux-kernel@...r.kernel.org, Leo Yan <leo.yan@....com>
Subject: [PATCH v2 3/8] coresight: Protect unregistration with mutex

The device registration is protected by CoreSight mutex to ensure the
atomic operations when adding a device onto bus.  One the other hand,
the locking is absent when unregister a device.

Use mutex to ensure atomicity on device unregistration.  During
unregistration, unbinding the associated CTI device is not included in
the locking region, as CTI has its own locking mechanism.

Fixes: 8c1d3f79d9ca ("coresight: core: Fix coresight device probe failure issue")
Signed-off-by: Leo Yan <leo.yan@....com>
---
 drivers/hwtracing/coresight/coresight-core.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c
index 6f21925a4913330a27db5d5836f34f13382339e7..b992ef5de8ddbd535e937c616bd7ab663f097f76 100644
--- a/drivers/hwtracing/coresight/coresight-core.c
+++ b/drivers/hwtracing/coresight/coresight-core.c
@@ -1429,14 +1429,17 @@ EXPORT_SYMBOL_GPL(coresight_register);
 
 void coresight_unregister(struct coresight_device *csdev)
 {
-	etm_perf_del_symlink_sink(csdev);
 	/* Remove references of that device in the topology */
 	if (cti_assoc_ops && cti_assoc_ops->remove)
 		cti_assoc_ops->remove(csdev);
+
+	mutex_lock(&coresight_mutex);
+	etm_perf_del_symlink_sink(csdev);
 	coresight_remove_conns(csdev);
 	coresight_clear_default_sink(csdev);
 	coresight_release_platform_data(csdev, csdev->dev.parent, csdev->pdata);
 	device_unregister(&csdev->dev);
+	mutex_unlock(&coresight_mutex);
 }
 EXPORT_SYMBOL_GPL(coresight_unregister);
 

-- 
2.34.1