[PATCH 1/1] tracing/boot: Add ftrace.instance.*.alloc_snapshot option
From: Masami Hiramatsu
Date: Sat Oct 10 2020 - 19:11:35 EST
Add ftrace.instance.*.alloc_snapshot option.
This option has been described in Documentation/trace/boottime-trace.rst
but not implemented yet.
ftrace.[instance.INSTANCE.]alloc_snapshot
Allocate snapshot buffer.
The difference from kernel.alloc_snapshot is that the kernel.alloc_snapshot
will allocate the buffer only for the main instance, but this can allocate
buffer for any new instances.
Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
---
kernel/trace/trace_boot.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/kernel/trace/trace_boot.c b/kernel/trace/trace_boot.c
index 754e3cf2df3a..c22a152ef0b4 100644
--- a/kernel/trace/trace_boot.c
+++ b/kernel/trace/trace_boot.c
@@ -284,6 +284,12 @@ trace_boot_enable_tracer(struct trace_array *tr, struct xbc_node *node)
if (tracing_set_tracer(tr, p) < 0)
pr_err("Failed to set given tracer: %s\n", p);
}
+
+ /* Since tracer can free snapshot buffer, allocate snapshot here.*/
+ if (xbc_node_find_value(node, "alloc_snapshot", NULL)) {
+ if (tracing_alloc_snapshot_instance(tr) < 0)
+ pr_err("Failed to allocate snapshot buffer\n");
+ }
}
static void __init