4.18-stable review patch. If anyone has any objections, please let me know.
------------------
From: Suzuki K Poulose <suzuki.poul...@arm.com>
[ Upstream commit 987d1e8dcd370d96029a3d76a0031b043c4a69ae ]
If the ETB is already enabled in sysfs mode, the ETB reports
success even if a perf mode is requested. Fix this by checking
the requested mode.
Cc: Mathieu Poirier <mathieu.poir...@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poul...@arm.com>
Signed-off-by: Mathieu Poirier <mathieu.poir...@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Signed-off-by: Sasha Levin <sas...@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
drivers/hwtracing/coresight/coresight-etb10.c | 4 ++++
1 file changed, 4 insertions(+)
--- a/drivers/hwtracing/coresight/coresight-etb10.c
+++ b/drivers/hwtracing/coresight/coresight-etb10.c
@@ -147,6 +147,10 @@ static int etb_enable(struct coresight_d
if (val == CS_MODE_PERF)
return -EBUSY;
+ /* Don't let perf disturb sysFS sessions */
+ if (val == CS_MODE_SYSFS && mode == CS_MODE_PERF)
+ return -EBUSY;
+
/* Nothing to do, the tracer is already enabled. */
if (val == CS_MODE_SYSFS)
goto out;
