4.18-stable review patch. If anyone has any objections, please let me know.
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From: Suzuki K Poulose suzuki.poulose@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.poirier@linaro.org Signed-off-by: Suzuki K Poulose suzuki.poulose@arm.com Signed-off-by: Mathieu Poirier mathieu.poirier@linaro.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@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;