linux-kernel - [PATCH 2/4] coresight: catu: add locking to catu enable/disable functions

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Message-ID: <20250418055820.3689408-3-hejunhao3@huawei.com>
Date: Fri, 18 Apr 2025 13:58:18 +0800
From: Junhao He <hejunhao3@...wei.com>
To: <suzuki.poulose@....com>, <james.clark@....com>,
	<anshuman.khandual@....com>, <mike.leach@...aro.org>, <leo.yan@....com>
CC: <coresight@...ts.linaro.org>, <linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>, <linuxarm@...wei.com>,
	<jonathan.cameron@...wei.com>, <yangyicong@...wei.com>,
	<hejunhao3@...wei.com>
Subject: [PATCH 2/4] coresight: catu: add locking to catu enable/disable functions

In the function coresight_enable_path(), all adjacent helper components
along the path are enabled first. Without proper locking, a race
condition may occur between concurrent sysfs and perf calls to these
functions, potentially leading to incorrectly obtained settings or
misconfigured CATU control-enable flags.

Requires spinlock in catu_enable()/catu_disable() to:
- Serialize sysfs/perf concurrent accesses
- Prevent corruption of CATU control-enable flags

Signed-off-by: Junhao He <hejunhao3@...wei.com>
---
 drivers/hwtracing/coresight/coresight-catu.c | 6 ++++++
 drivers/hwtracing/coresight/coresight-catu.h | 1 +
 2 files changed, 7 insertions(+)

diff --git a/drivers/hwtracing/coresight/coresight-catu.c b/drivers/hwtracing/coresight/coresight-catu.c
index 275cc0d9f505..54ce13254d7c 100644
--- a/drivers/hwtracing/coresight/coresight-catu.c
+++ b/drivers/hwtracing/coresight/coresight-catu.c
@@ -461,6 +461,8 @@ static int catu_enable(struct coresight_device *csdev, enum cs_mode mode,
 	int rc;
 	struct catu_drvdata *catu_drvdata = csdev_to_catu_drvdata(csdev);
 
+	guard(spinlock_irqsave)(&catu_drvdata->spinlock);
+
 	CS_UNLOCK(catu_drvdata->base);
 	rc = catu_enable_hw(catu_drvdata, mode, data);
 	CS_LOCK(catu_drvdata->base);
@@ -489,6 +491,8 @@ static int catu_disable(struct coresight_device *csdev, void *__unused)
 	int rc;
 	struct catu_drvdata *catu_drvdata = csdev_to_catu_drvdata(csdev);
 
+	guard(spinlock_irqsave)(&catu_drvdata->spinlock);
+
 	CS_UNLOCK(catu_drvdata->base);
 	rc = catu_disable_hw(catu_drvdata);
 	CS_LOCK(catu_drvdata->base);
@@ -523,6 +527,8 @@ static int __catu_probe(struct device *dev, struct resource *res)
 		goto out;
 	}
 
+	spin_lock_init(&drvdata->spinlock);
+
 	/* Setup dma mask for the device */
 	dma_mask = readl_relaxed(base + CORESIGHT_DEVID) & 0x3f;
 	switch (dma_mask) {
diff --git a/drivers/hwtracing/coresight/coresight-catu.h b/drivers/hwtracing/coresight/coresight-catu.h
index 141feac1c14b..eb7c9189b066 100644
--- a/drivers/hwtracing/coresight/coresight-catu.h
+++ b/drivers/hwtracing/coresight/coresight-catu.h
@@ -64,6 +64,7 @@ struct catu_drvdata {
 	struct clk *pclk;
 	void __iomem *base;
 	struct coresight_device *csdev;
+	spinlock_t spinlock;
 	int irq;
 };
 
-- 
2.33.0