[PATCH v4 02/10] coresight: etm-perf: Remove workqueue for freeing AUX data

[James Clark]

AUX cleanup is deferred to a workqueue which is never flushed on module
unload. Pending work items can therefore run after coresight-config is
cleaned up or the module text is unloaded.

Since commit 95ff4ca26c49 ("perf/core: Free AUX pages in unmap path"), Perf
core stops AUX transactions and frees the PMU AUX data from the unmap
path in non-atomic context. Release the resources directly from the
free_aux() callback and remove the workqueue.

Fixes: 0bcbf2e30ff2 ("coresight: etm-perf: new PMU driver for ETM tracers")
Signed-off-by: James Clark <james.clark at linaro.org>
---
 drivers/hwtracing/coresight/coresight-etm-perf.c | 14 ++------------
 drivers/hwtracing/coresight/coresight-etm-perf.h |  2 --
 2 files changed, 2 insertions(+), 14 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c
index 09b21a711a87..2323a68584d4 100644
--- a/drivers/hwtracing/coresight/coresight-etm-perf.c
+++ b/drivers/hwtracing/coresight/coresight-etm-perf.c
@@ -18,7 +18,6 @@
 #include <linux/slab.h>
 #include <linux/stringhash.h>
 #include <linux/types.h>
-#include <linux/workqueue.h>
 
 #include "coresight-config.h"
 #include "coresight-etm-perf.h"
@@ -211,13 +210,12 @@ static void free_sink_buffer(struct etm_event_data *event_data)
 	sink_ops(sink)->free_buffer(event_data->snk_config);
 }
 
-static void free_event_data(struct work_struct *work)
+static void etm_free_aux(void *data)
 {
 	int cpu;
 	cpumask_t *mask;
-	struct etm_event_data *event_data;
+	struct etm_event_data *event_data = data;
 
-	event_data = container_of(work, struct etm_event_data, work);
 	mask = &event_data->mask;
 
 	/* Free the sink buffers, if there are any */
@@ -288,13 +286,6 @@ static void *alloc_event_data(int cpu)
 	return event_data;
 }
 
-static void etm_free_aux(void *data)
-{
-	struct etm_event_data *event_data = data;
-
-	schedule_work(&event_data->work);
-}
-
 /*
  * Check if two given sinks are compatible with each other,
  * so that they can use the same sink buffers, when an event
@@ -436,7 +427,6 @@ static void *etm_setup_aux(struct perf_event *event, void **pages,
 	event_data = alloc_event_data(cpu);
 	if (!event_data)
 		return NULL;
-	INIT_WORK(&event_data->work, free_event_data);
 
 	/* First get the selected sink from user space. */
 	sink_hash = ATTR_CFG_GET_FLD(&event->attr, sinkid);
diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.h b/drivers/hwtracing/coresight/coresight-etm-perf.h
index 24d929428633..5e8d985522bd 100644
--- a/drivers/hwtracing/coresight/coresight-etm-perf.h
+++ b/drivers/hwtracing/coresight/coresight-etm-perf.h
@@ -84,7 +84,6 @@ struct etm_filters {
 
 /**
  * struct etm_event_data - Coresight specifics associated to an event
- * @work:		Handle to free allocated memory outside IRQ context.
  * @mask:		Hold the CPU(s) this event was set for.
  * @aux_hwid_done:	Whether a CPU has emitted the TraceID packet or not.
  * @snk_config:		The sink configuration.
@@ -92,7 +91,6 @@ struct etm_filters {
  * @path:		An array of path, each slot for one CPU.
  */
 struct etm_event_data {
-	struct work_struct work;
 	cpumask_t mask;
 	cpumask_t aux_hwid_done;
 	void *snk_config;

-- 
2.43.0