| From: Tom Zanussi <tom.zanussi@linux.intel.com> |
| Date: Tue, 5 Sep 2017 16:57:37 -0500 |
| Subject: [PATCH 25/40] tracing: Add support for dynamic tracepoints |
| |
| 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 <tom.zanussi@linux.intel.com> |
| Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> |
| --- |
| include/linux/tracepoint-defs.h | 1 + |
| kernel/tracepoint.c | 18 +++++++++++++----- |
| 2 files changed, 14 insertions(+), 5 deletions(-) |
| |
| --- 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 |
| --- a/kernel/tracepoint.c |
| +++ b/kernel/tracepoint.c |
| @@ -197,7 +197,9 @@ static int tracepoint_add_func(struct tr |
| 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 tr |
| * 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 |
| |
| 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_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 |