On 07/31/2018 06:07 PM, Mathieu Poirier wrote:
Hello,

On Thu, Jul 26, 2018 at 01:54:40PM +0100, Suzuki K Poulose wrote:
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>
---
  drivers/hwtracing/coresight/coresight-etb10.c | 8 ++++++--
  1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etb10.c 
b/drivers/hwtracing/coresight/coresight-etb10.c
index 306119e..e5808fd 100644
--- a/drivers/hwtracing/coresight/coresight-etb10.c
+++ b/drivers/hwtracing/coresight/coresight-etb10.c
@@ -148,8 +148,12 @@ static int etb_enable(struct coresight_device *csdev, u32 
mode)
                return -EBUSY;
/* Nothing to do, the tracer is already enabled. */
-       if (val == CS_MODE_SYSFS)
-               goto out;
+       if (val == CS_MODE_SYSFS) {
+               if (mode == CS_MODE_SYSFS)
+                       goto out;
+               else
+                       return -EBUSY;
+       }

How about:

         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;


I just find it more readable that way.

Sure, thats fine by me.

Cheers
Suzuki

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