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| author |   Steven Rostedt (VMware) <rostedt@goodmis.org> | 2021-08-16 23:42:57 -0400 |
|---|---|---|
| committer | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2021-08-18 18:13:47 -0400 |
| commit | 1d18538e6a09265003a0a94ca779d7a6127cb76c (patch) | |
| tree | 79c71bb9a4c4ed5a3848bdbb155b6b1dfe8a08a0 /include/linux/trace_events.h | |
| parent | tracing: Add DYNAMIC flag for dynamic events (diff) | |
| download | linux-dev-1d18538e6a09265003a0a94ca779d7a6127cb76c.tar.xz linux-dev-1d18538e6a09265003a0a94ca779d7a6127cb76c.zip | |
tracing: Have dynamic events have a ref counter
As dynamic events are not created by modules, if something is attached to
one, calling "try_module_get()" on its "mod" field, is not going to keep
the dynamic event from going away.
Since dynamic events do not need the "mod" pointer of the event structure,
make a union out of it in order to save memory (there's one structure for
each of the thousand+ events in the kernel), and have any event with the
DYNAMIC flag set to use a ref counter instead.
Link: https://lore.kernel.org/linux-trace-devel/20210813004448.51c7de69ce432d338f4d226b@kernel.org/
Link: https://lkml.kernel.org/r/20210817035027.174869074@goodmis.org
Suggested-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'include/linux/trace_events.h')
| -rw-r--r-- | include/linux/trace_events.h | 45 |
1 files changed, 44 insertions, 1 deletions
diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h index 53c9dffd87fd..9564c4d9a3b6 100644 --- a/include/linux/trace_events.h +++ b/include/linux/trace_events.h @@ -350,7 +350,14 @@ struct trace_event_call { struct trace_event event; char *print_fmt; struct event_filter *filter; - void *mod; + /* + * Static events can disappear with modules, + * where as dynamic ones need their own ref count. + */ + union { + void *module; + atomic_t refcnt; + }; void *data; /* See the TRACE_EVENT_FL_* flags above */ @@ -366,6 +373,42 @@ struct trace_event_call { #endif }; +#ifdef CONFIG_DYNAMIC_EVENTS +bool trace_event_dyn_try_get_ref(struct trace_event_call *call); +void trace_event_dyn_put_ref(struct trace_event_call *call); +bool trace_event_dyn_busy(struct trace_event_call *call); +#else +static inline bool trace_event_dyn_try_get_ref(struct trace_event_call *call) +{ + /* Without DYNAMIC_EVENTS configured, nothing should be calling this */ + return false; +} +static inline void trace_event_dyn_put_ref(struct trace_event_call *call) +{ +} +static inline bool trace_event_dyn_busy(struct trace_event_call *call) +{ + /* Nothing should call this without DYNAIMIC_EVENTS configured. */ + return true; +} +#endif + +static inline bool trace_event_try_get_ref(struct trace_event_call *call) +{ + if (call->flags & TRACE_EVENT_FL_DYNAMIC) + return trace_event_dyn_try_get_ref(call); + else + return try_module_get(call->module); +} + +static inline void trace_event_put_ref(struct trace_event_call *call) +{ + if (call->flags & TRACE_EVENT_FL_DYNAMIC) + trace_event_dyn_put_ref(call); + else + module_put(call->module); +} + #ifdef CONFIG_PERF_EVENTS static inline bool bpf_prog_array_valid(struct trace_event_call *call) { |