From: James Clark <james.clark@linaro.org>
Date: Thu, 28 Nov 2024 12:14:14 +0000 (+0000)
Subject: coresight: Drop atomics in connection refcounts
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=5aec7c065fba0c56d6c1ea5d629395210f174be8;p=users%2Fjedix%2Flinux-maple.git

coresight: Drop atomics in connection refcounts

These belong to the device being enabled or disabled and are only ever
used inside the device's spinlock. Remove the atomics to not imply that
there are any other concurrent accesses.

If atomics were necessary I don't think they would have been enough
anyway. There would be nothing to prevent an enable or disable running
concurrently if not for the spinlock.

Signed-off-by: James Clark <james.clark@linaro.org>
Reviewed-by: Yeoreum Yun <yeoreum.yun@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20241128121414.2425119-1-james.clark@linaro.org
---

diff --git a/drivers/hwtracing/coresight/coresight-funnel.c b/drivers/hwtracing/coresight/coresight-funnel.c
index 33efe1acbef75..8faf51469bb8c 100644
--- a/drivers/hwtracing/coresight/coresight-funnel.c
+++ b/drivers/hwtracing/coresight/coresight-funnel.c
@@ -86,14 +86,14 @@ static int funnel_enable(struct coresight_device *csdev,
 	bool first_enable = false;
 
 	spin_lock_irqsave(&drvdata->spinlock, flags);
-	if (atomic_read(&in->dest_refcnt) == 0) {
+	if (in->dest_refcnt == 0) {
 		if (drvdata->base)
 			rc = dynamic_funnel_enable_hw(drvdata, in->dest_port);
 		if (!rc)
 			first_enable = true;
 	}
 	if (!rc)
-		atomic_inc(&in->dest_refcnt);
+		in->dest_refcnt++;
 	spin_unlock_irqrestore(&drvdata->spinlock, flags);
 
 	if (first_enable)
@@ -130,7 +130,7 @@ static void funnel_disable(struct coresight_device *csdev,
 	bool last_disable = false;
 
 	spin_lock_irqsave(&drvdata->spinlock, flags);
-	if (atomic_dec_return(&in->dest_refcnt) == 0) {
+	if (--in->dest_refcnt == 0) {
 		if (drvdata->base)
 			dynamic_funnel_disable_hw(drvdata, in->dest_port);
 		last_disable = true;
diff --git a/drivers/hwtracing/coresight/coresight-replicator.c b/drivers/hwtracing/coresight/coresight-replicator.c
index 0fba87de6d1af..a1181c9048c08 100644
--- a/drivers/hwtracing/coresight/coresight-replicator.c
+++ b/drivers/hwtracing/coresight/coresight-replicator.c
@@ -126,7 +126,7 @@ static int replicator_enable(struct coresight_device *csdev,
 	bool first_enable = false;
 
 	spin_lock_irqsave(&drvdata->spinlock, flags);
-	if (atomic_read(&out->src_refcnt) == 0) {
+	if (out->src_refcnt == 0) {
 		if (drvdata->base)
 			rc = dynamic_replicator_enable(drvdata, in->dest_port,
 						       out->src_port);
@@ -134,7 +134,7 @@ static int replicator_enable(struct coresight_device *csdev,
 			first_enable = true;
 	}
 	if (!rc)
-		atomic_inc(&out->src_refcnt);
+		out->src_refcnt++;
 	spin_unlock_irqrestore(&drvdata->spinlock, flags);
 
 	if (first_enable)
@@ -180,7 +180,7 @@ static void replicator_disable(struct coresight_device *csdev,
 	bool last_disable = false;
 
 	spin_lock_irqsave(&drvdata->spinlock, flags);
-	if (atomic_dec_return(&out->src_refcnt) == 0) {
+	if (--out->src_refcnt == 0) {
 		if (drvdata->base)
 			dynamic_replicator_disable(drvdata, in->dest_port,
 						   out->src_port);
diff --git a/drivers/hwtracing/coresight/coresight-tpda.c b/drivers/hwtracing/coresight/coresight-tpda.c
index bfca103f9f847..4ec676bea1cea 100644
--- a/drivers/hwtracing/coresight/coresight-tpda.c
+++ b/drivers/hwtracing/coresight/coresight-tpda.c
@@ -190,10 +190,10 @@ static int tpda_enable(struct coresight_device *csdev,
 	int ret = 0;
 
 	spin_lock(&drvdata->spinlock);
-	if (atomic_read(&in->dest_refcnt) == 0) {
+	if (in->dest_refcnt == 0) {
 		ret = __tpda_enable(drvdata, in->dest_port);
 		if (!ret) {
-			atomic_inc(&in->dest_refcnt);
+			in->dest_refcnt++;
 			csdev->refcnt++;
 			dev_dbg(drvdata->dev, "TPDA inport %d enabled.\n", in->dest_port);
 		}
@@ -223,7 +223,7 @@ static void tpda_disable(struct coresight_device *csdev,
 	struct tpda_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
 
 	spin_lock(&drvdata->spinlock);
-	if (atomic_dec_return(&in->dest_refcnt) == 0) {
+	if (--in->dest_refcnt == 0) {
 		__tpda_disable(drvdata, in->dest_port);
 		csdev->refcnt--;
 	}
diff --git a/include/linux/coresight.h b/include/linux/coresight.h
index c133425942785..834029cb9ba2c 100644
--- a/include/linux/coresight.h
+++ b/include/linux/coresight.h
@@ -200,8 +200,8 @@ struct coresight_connection {
 	struct coresight_device *dest_dev;
 	struct coresight_sysfs_link *link;
 	struct coresight_device *src_dev;
-	atomic_t src_refcnt;
-	atomic_t dest_refcnt;
+	int src_refcnt;
+	int dest_refcnt;
 };
 
 /**