[PATCH v2 25/40] tracing: Add support for dynamic tracepoints
From: Tom Zanussi <hidden>
Date: 2017-09-05 21:59:17
Also in:
lkml
Subsystem:
the rest, tracing · Maintainers:
Linus Torvalds, Steven Rostedt, Masami Hiramatsu
The tracepoint infrastructure assumes statically-defined tracepoints and uses static_keys for tracepoint enablement. In order to define tracepoints on the fly, we need to have a dynamic counterpart. Add a 'dynamic' flag to struct tracepoint along with accompanying logic for this purpose. Signed-off-by: Tom Zanussi <redacted> --- include/linux/tracepoint-defs.h | 1 + kernel/tracepoint.c | 18 +++++++++++++----- 2 files changed, 14 insertions(+), 5 deletions(-)
diff --git a/include/linux/tracepoint-defs.h b/include/linux/tracepoint-defs.h
index a031920..bc22d54 100644
--- a/include/linux/tracepoint-defs.h
+++ b/include/linux/tracepoint-defs.h@@ -32,6 +32,7 @@ struct tracepoint { int (*regfunc)(void); void (*unregfunc)(void); struct tracepoint_func __rcu *funcs; + bool dynamic; }; #endif
diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index 685c50a..1c5957f 100644
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c@@ -197,7 +197,9 @@ static int tracepoint_add_func(struct tracepoint *tp, struct tracepoint_func *old, *tp_funcs; int ret; - if (tp->regfunc && !static_key_enabled(&tp->key)) { + if (tp->regfunc && + ((tp->dynamic && !(atomic_read(&tp->key.enabled) > 0)) || + !static_key_enabled(&tp->key))) { ret = tp->regfunc(); if (ret < 0) return ret;
@@ -219,7 +221,9 @@ static int tracepoint_add_func(struct tracepoint *tp, * is used. */ rcu_assign_pointer(tp->funcs, tp_funcs); - if (!static_key_enabled(&tp->key)) + if (tp->dynamic && !(atomic_read(&tp->key.enabled) > 0)) + atomic_inc(&tp->key.enabled); + else if (!tp->dynamic && !static_key_enabled(&tp->key)) static_key_slow_inc(&tp->key); release_probes(old); return 0;
@@ -246,10 +250,14 @@ static int tracepoint_remove_func(struct tracepoint *tp, if (!tp_funcs) { /* Removed last function */ - if (tp->unregfunc && static_key_enabled(&tp->key)) + if (tp->unregfunc && + ((tp->dynamic && (atomic_read(&tp->key.enabled) > 0)) || + static_key_enabled(&tp->key))) tp->unregfunc(); - if (static_key_enabled(&tp->key)) + if (tp->dynamic && (atomic_read(&tp->key.enabled) > 0)) + atomic_dec(&tp->key.enabled); + else if (!tp->dynamic && static_key_enabled(&tp->key)) static_key_slow_dec(&tp->key); } rcu_assign_pointer(tp->funcs, tp_funcs);
@@ -258,7 +266,7 @@ static int tracepoint_remove_func(struct tracepoint *tp, } /** - * tracepoint_probe_register - Connect a probe to a tracepoint + * tracepoint_probe_register_prio - Connect a probe to a tracepoint * @tp: tracepoint * @probe: probe handler * @data: tracepoint data
--
1.9.3