coresight: add verification process for coresight_etm_get_trace_id

The coresight_etm_get_trace_id function is a global function. The
verification process for 'csdev' is required prior to its usage.

Fixes: c367a89 ("Coresight: Add trace_id function to retrieving the trace ID")
Signed-off-by: Jie Gan <[email protected]>
Signed-off-by: Suzuki K Poulose <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: Jie Gan

drivers/hwtracing/coresight/coresight-core.c

@@ -1616,9 +1616,12 @@ EXPORT_SYMBOL_GPL(coresight_remove_driver);
 int coresight_etm_get_trace_id(struct coresight_device *csdev, enum cs_mode mode,
 			       struct coresight_device *sink)
 {
-	int trace_id;
-	int cpu = source_ops(csdev)->cpu_id(csdev);
+	int cpu, trace_id;
+
+	if (csdev->type != CORESIGHT_DEV_TYPE_SOURCE || !source_ops(csdev)->cpu_id)
+		return -EINVAL;
 
+	cpu = source_ops(csdev)->cpu_id(csdev);
 	switch (mode) {
 	case CS_MODE_SYSFS:
 		trace_id = coresight_trace_id_get_cpu_id(cpu);