stm class: Rework policy node fallback

Currently, if no matching policy node can be found for a trace source,
we'll try to use "default" policy node, then, if that doesn't exist,
we'll pick the first node, in order of creation. If that also fails,
we'll allocate M/C range from the beginning of the device's M/C range.

This makes it difficult to know which node (if any) was used in any
particular case.

In order to make things more deterministic, the new order is as follows:
  * if they supply ID string, use that and nothing else,
  * if they are a task, use their task name (comm),
  * use "default", if it exists,
  * return failure, to let them know there is no suitable rule.

This should provide enough convenience with the "default" catch-all node,
while not leaving *everything* to chance. As a side effect, this relaxes
the requirement of using ioctl() for identification with the possibility of
using task names as policy nodes.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Tested-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 0 insertions, 2 deletions

diff --git a/drivers/hwtracing/stm/stm.h b/drivers/hwtracing/stm/stm.h
index 923571adc6f4..e5df08ae59cf 100644
--- a/drivers/hwtracing/stm/stm.h
+++ b/drivers/hwtracing/stm/stm.h
@@ -57,7 +57,6 @@ struct stm_output {
 
 struct stm_file {
 	struct stm_device	*stm;
-	struct stp_policy_node	*policy_node;
 	struct stm_output	output;
 };
 
@@ -71,7 +70,6 @@ struct stm_source_device {
 	struct stm_device __rcu	*link;
 	struct list_head	link_entry;
 	/* one output per stm_source device */
-	struct stp_policy_node	*policy_node;
 	struct stm_output	output;
 };