Based on the following report from Smatch tool, make sure we have a valid drvdata before we dereference it to find the real dev.
The patch 21d26b905c05: "coresight: etm: Clean up device specific data" from May 22, 2019, leads to the following Smatch complaint:
./drivers/hwtracing/coresight/coresight-etm3x.c:460 etm_get_trace_id() warn: variable dereferenced before check 'drvdata' (see line 458)
./drivers/hwtracing/coresight/coresight-etm3x.c 457 int trace_id = -1; 458 struct device *etm_dev = drvdata->csdev->dev.parent; ^^^^^^^^^ New dereference
459 460 if (!drvdata) ^^^^^^^^ Checked too late. Delete the check?
461 goto out; 462
Cc: Mathieu Poirier mathieu.poirier@linaro.org Cc: Dan Carpenter dan.carpenter@oracle.com Signed-off-by: Suzuki K Poulose suzuki.poulose@arm.com --- drivers/hwtracing/coresight/coresight-etm3x.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/hwtracing/coresight/coresight-etm3x.c b/drivers/hwtracing/coresight/coresight-etm3x.c index bed7291..225c298 100644 --- a/drivers/hwtracing/coresight/coresight-etm3x.c +++ b/drivers/hwtracing/coresight/coresight-etm3x.c @@ -455,11 +455,12 @@ int etm_get_trace_id(struct etm_drvdata *drvdata) { unsigned long flags; int trace_id = -1; - struct device *etm_dev = drvdata->csdev->dev.parent; + struct device *etm_dev;
if (!drvdata) goto out;
+ etm_dev = drvdata->csdev->dev.parent; if (!local_read(&drvdata->mode)) return drvdata->traceid;