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Subject[RFC PATCH v4 19/22] tracing/boot: Add instance node support
Date
Add instance node support to boot-time tracing. User can set
some options and event nodes under instance node.

- ftrace.instance.INSTANCE[...]
Add new INSTANCE instance. Some options and event nodes
are acceptable for instance node.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
Changes in v4:
- Use trace_array_get_by_name() instead of trace_array_create().
- Remove global boot option setting.
---
kernel/trace/trace_boot.c | 43 ++++++++++++++++++++++++++++++++++++++-----
1 file changed, 38 insertions(+), 5 deletions(-)

diff --git a/kernel/trace/trace_boot.c b/kernel/trace/trace_boot.c
index 3054921b0877..f5db30d25b0b 100644
--- a/kernel/trace/trace_boot.c
+++ b/kernel/trace/trace_boot.c
@@ -20,7 +20,7 @@ extern ssize_t tracing_resize_ring_buffer(struct trace_array *tr,
unsigned long size, int cpu_id);

static void __init
-trace_boot_set_ftrace_options(struct trace_array *tr, struct xbc_node *node)
+trace_boot_set_instance_options(struct trace_array *tr, struct xbc_node *node)
{
struct xbc_node *anode;
const char *p;
@@ -242,6 +242,40 @@ trace_boot_enable_tracer(struct trace_array *tr, struct xbc_node *node)
}
}

+static void __init
+trace_boot_init_one_instance(struct trace_array *tr, struct xbc_node *node)
+{
+ trace_boot_set_instance_options(tr, node);
+ trace_boot_init_events(tr, node);
+ trace_boot_enable_events(tr, node);
+ trace_boot_enable_tracer(tr, node);
+}
+
+static void __init
+trace_boot_init_instances(struct xbc_node *node)
+{
+ struct xbc_node *inode;
+ struct trace_array *tr;
+ const char *p;
+
+ node = xbc_node_find_child(node, "instance");
+ if (!node)
+ return;
+
+ xbc_node_for_each_child(node, inode) {
+ p = xbc_node_get_data(inode);
+ if (!p || *p == '\0')
+ continue;
+
+ tr = trace_array_get_by_name(p);
+ if (IS_ERR(tr)) {
+ pr_err("Failed to get trace instance %s\n", p);
+ continue;
+ }
+ trace_boot_init_one_instance(tr, inode);
+ }
+}
+
static int __init trace_boot_init(void)
{
struct xbc_node *trace_node;
@@ -255,10 +289,9 @@ static int __init trace_boot_init(void)
if (!tr)
return 0;

- trace_boot_set_ftrace_options(tr, trace_node);
- trace_boot_init_events(tr, trace_node);
- trace_boot_enable_events(tr, trace_node);
- trace_boot_enable_tracer(tr, trace_node);
+ /* Global trace array is also one instance */
+ trace_boot_init_one_instance(tr, trace_node);
+ trace_boot_init_instances(trace_node);

return 0;
}
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