[PATCH 19/24] gtrace: Add setup_sysfs_buf callback to setup sysfs sink buffer

[Zane Leung]

Add a setup_sysfs_buf() callback to gtrace_driver and invoke it from
gtrace_enable_sysfs() before the path is started, so the sink can
allocate its sysfs trace buffer outside the spinlock held by the core
start path.

Signed-off-by: Zane Leung <liangzhen@xxxxxxxxxxxxxxxxxx>
---
 drivers/hwtracing/gtrace/gtrace-sysfs.c | 12 ++++++++++++
 include/linux/gtrace.h                  |  2 ++
 2 files changed, 14 insertions(+)

diff --git a/drivers/hwtracing/gtrace/gtrace-sysfs.c b/drivers/hwtracing/gtrace/gtrace-sysfs.c
index 5f4f3fcb56a4..23b0a21ef9c0 100644
--- a/drivers/hwtracing/gtrace/gtrace-sysfs.c
+++ b/drivers/hwtracing/gtrace/gtrace-sysfs.c
@@ -85,6 +85,7 @@ static int gtrace_validate_source_sysfs(struct gtrace_component *comp,
 int gtrace_enable_sysfs(struct gtrace_component *comp)
 {
 	struct gtrace_component *sink;
+	struct gtrace_driver *sinkdrv;
 	struct gtrace_path *path;
 	int ret;
 
@@ -114,6 +115,17 @@ int gtrace_enable_sysfs(struct gtrace_component *comp)
 
 	mutex_lock(&gtrace_mutex);
 
+	if (!sink)
+		sink = gtrace_path_sink(path);
+	sinkdrv = to_gtrace_driver(sink->dev.driver);
+	if (sinkdrv && sinkdrv->setup_sysfs_buf) {
+		ret = sinkdrv->setup_sysfs_buf(sink);
+		if (ret) {
+			gtrace_destroy_path(path);
+			goto out;
+		}
+	}
+
 	ret = gtrace_path_start(path);
 	if (ret)
 		gtrace_destroy_path(path);
diff --git a/include/linux/gtrace.h b/include/linux/gtrace.h
index a3d125882ec9..0957d0490c57 100644
--- a/include/linux/gtrace.h
+++ b/include/linux/gtrace.h
@@ -377,6 +377,7 @@ int gtrace_path_copyto_auxbuf(struct gtrace_path *path,
 /**
  * struct gtrace_driver - Representation of a trace driver.
  * @id_table:      Table to match components handled by the driver.
+ * @setup_sysfs_buf: Callback to setup sink-specific sysfs buffer.
  * @alloc_buf:     Callback to alloc sink-specific buffer.
  * @free_buf:      Callback to free sink-specific buffer.
  * @copyto_auxbuf: Callback to copy data into perf AUX buffer. The driver
@@ -394,6 +395,7 @@ int gtrace_path_copyto_auxbuf(struct gtrace_path *path,
  */
 struct gtrace_driver {
 	const struct gtrace_component_id *id_table;
+	int			(*setup_sysfs_buf)(struct gtrace_component *comp);
 	void			*(*alloc_buf)(struct gtrace_component *comp,
 					     struct perf_event *event, void **pages,
 					     int nr_pages, bool overwrite);
-- 
2.34.1