linux-kernel - [PATCH v3 20/30] coresight: Cleanup coresight_remove

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Date:   Tue,  7 May 2019 11:52:47 +0100
From:   Suzuki K Poulose <suzuki.poulose@....com>
To:     linux-arm-kernel@...ts.infradead.org
Cc:     linux-kernel@...r.kernel.org, coresight@...ts.linaro.org,
        rjw@...ysocki.net, mathieu.poirier@...aro.org,
        Suzuki K Poulose <suzuki.poulose@....com>
Subject: [PATCH v3 20/30] coresight: Cleanup coresight_remove_conns

When a device is unregistered, we remove all connection
references to it, by searching the connection records of
all devices in the coresight bus, via coresight_remove_conns.
We could avoid searching if this device doesn't have an input
port (e.g, a source). Also document the purpose of the function.

Reviewed-by: Mathieu Poirier <mathieu.poirier@...aro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
---
 drivers/hwtracing/coresight/coresight.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight.c b/drivers/hwtracing/coresight/coresight.c
index 04b5d3c..068bd2f 100644
--- a/drivers/hwtracing/coresight/coresight.c
+++ b/drivers/hwtracing/coresight/coresight.c
@@ -1096,10 +1096,21 @@ static int coresight_remove_match(struct device *dev, void *data)
 	return 0;
 }
 
+/*
+ * coresight_remove_conns - Remove references to this given devices
+ * from the connections of other devices.
+ */
 static void coresight_remove_conns(struct coresight_device *csdev)
 {
-	bus_for_each_dev(&coresight_bustype, NULL,
-			 csdev, coresight_remove_match);
+	/*
+	 * Another device will point to this device only if there is
+	 * an output port connected to this one. i.e, if the device
+	 * doesn't have at least one input port, there is no point
+	 * in searching all the devices.
+	 */
+	if (csdev->nr_inport)
+		bus_for_each_dev(&coresight_bustype, NULL,
+				 csdev, coresight_remove_match);
 }
 
 /**
-- 
2.7.4