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SubjectRe: [PATCH -tip v8 6/7] tracing: ftrace dynamic ftrace_event_call support

On Thu, 28 May 2009, Masami Hiramatsu wrote:

> Add dynamic ftrace_event_call support to ftrace. Trace engines can adds new
> ftrace_event_call to ftrace on the fly. Each operator functions of the call
> takes a ftrace_event_call data structure as an argument, because these
> functions may be shared among several ftrace_event_calls.
>
> Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Ingo Molnar <mingo@elte.hu>
> Cc: Tom Zanussi <tzanussi@gmail.com>
> Cc: Frederic Weisbecker <fweisbec@gmail.com>
> ---
>
> include/linux/ftrace_event.h | 13 ++++++----
> include/trace/ftrace.h | 22 +++++++++--------
> kernel/trace/trace_events.c | 54 +++++++++++++++++++++++++++++-------------
> kernel/trace/trace_export.c | 27 ++++++++++-----------
> 4 files changed, 69 insertions(+), 47 deletions(-)
>
> diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
> index bbf40f6..e25f3a4 100644
> --- a/include/linux/ftrace_event.h
> +++ b/include/linux/ftrace_event.h
> @@ -108,12 +108,13 @@ struct ftrace_event_call {
> struct dentry *dir;
> struct trace_event *event;
> int enabled;
> - int (*regfunc)(void);
> - void (*unregfunc)(void);
> + int (*regfunc)(struct ftrace_event_call *);
> + void (*unregfunc)(struct ftrace_event_call *);
> int id;
> - int (*raw_init)(void);
> - int (*show_format)(struct trace_seq *s);
> - int (*define_fields)(void);
> + int (*raw_init)(struct ftrace_event_call *);
> + int (*show_format)(struct ftrace_event_call *,
> + struct trace_seq *);
> + int (*define_fields)(struct ftrace_event_call *);
> struct list_head fields;
> int filter_active;
> void *filter;
> @@ -138,6 +139,8 @@ extern int filter_current_check_discard(struct ftrace_event_call *call,
>
> extern int trace_define_field(struct ftrace_event_call *call, char *type,
> char *name, int offset, int size, int is_signed);
> +extern int trace_add_event_call(struct ftrace_event_call *call);
> +extern void trace_remove_event_call(struct ftrace_event_call *call);
>
> #define is_signed_type(type) (((type)(-1)) < 0)
>
> diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
> index b4ec83a..de3ee7c 100644
> --- a/include/trace/ftrace.h
> +++ b/include/trace/ftrace.h
> @@ -229,7 +229,8 @@ ftrace_raw_output_##call(struct trace_iterator *iter, int flags) \
> #undef TRACE_EVENT
> #define TRACE_EVENT(call, proto, args, tstruct, func, print) \
> static int \
> -ftrace_format_##call(struct trace_seq *s) \
> +ftrace_format_##call(struct ftrace_event_call *event_call, \
> + struct trace_seq *s) \
> { \
> struct ftrace_raw_##call field __attribute__((unused)); \
> int ret = 0; \
> @@ -269,10 +270,9 @@ ftrace_format_##call(struct trace_seq *s) \
> #undef TRACE_EVENT
> #define TRACE_EVENT(call, proto, args, tstruct, func, print) \
> int \
> -ftrace_define_fields_##call(void) \
> +ftrace_define_fields_##call(struct ftrace_event_call *event_call) \
> { \
> struct ftrace_raw_##call field; \
> - struct ftrace_event_call *event_call = &event_##call; \
> int ret; \
> \
> __common_field(int, type, 1); \
> @@ -298,7 +298,7 @@ ftrace_define_fields_##call(void) \
> * event_trace_printk(_RET_IP_, "<call>: " <fmt>);
> * }
> *
> - * static int ftrace_reg_event_<call>(void)
> + * static int ftrace_reg_event_<call>(struct ftrace_event_call *dummy)

I would prefer "unused" or similar as a variable name over "dummy".

> * {
> * int ret;
> *
> @@ -309,7 +309,7 @@ ftrace_define_fields_##call(void) \
> * return ret;
> * }
> *
> - * static void ftrace_unreg_event_<call>(void)
> + * static void ftrace_unreg_event_<call>(struct ftrace_event_call *dummy)
> * {
> * unregister_trace_<call>(ftrace_event_<call>);
> * }
> @@ -342,7 +342,7 @@ ftrace_define_fields_##call(void) \
> * trace_current_buffer_unlock_commit(event, irq_flags, pc);
> * }
> *
> - * static int ftrace_raw_reg_event_<call>(void)
> + * static int ftrace_raw_reg_event_<call>(struct ftrace_event_call *dummy)
> * {
> * int ret;
> *
> @@ -353,7 +353,7 @@ ftrace_define_fields_##call(void) \
> * return ret;
> * }
> *
> - * static void ftrace_unreg_event_<call>(void)
> + * static void ftrace_unreg_event_<call>(struct ftrace_event_call *dummy)
> * {
> * unregister_trace_<call>(ftrace_raw_event_<call>);
> * }
> @@ -362,7 +362,7 @@ ftrace_define_fields_##call(void) \
> * .trace = ftrace_raw_output_<call>, <-- stage 2
> * };
> *
> - * static int ftrace_raw_init_event_<call>(void)
> + * static int ftrace_raw_init_event_<call>(struct ftrace_event_call *dummy)
> * {
> * int id;
> *
> @@ -477,7 +477,7 @@ static void ftrace_raw_event_##call(proto) \
> trace_nowake_buffer_unlock_commit(event, irq_flags, pc); \
> } \
> \
> -static int ftrace_raw_reg_event_##call(void) \
> +static int ftrace_raw_reg_event_##call(struct ftrace_event_call *dummy) \
> { \
> int ret; \
> \
> @@ -488,7 +488,7 @@ static int ftrace_raw_reg_event_##call(void) \
> return ret; \
> } \
> \
> -static void ftrace_raw_unreg_event_##call(void) \
> +static void ftrace_raw_unreg_event_##call(struct ftrace_event_call *dummy)\
> { \
> unregister_trace_##call(ftrace_raw_event_##call); \
> } \
> @@ -497,7 +497,7 @@ static struct trace_event ftrace_event_type_##call = { \
> .trace = ftrace_raw_output_##call, \
> }; \
> \
> -static int ftrace_raw_init_event_##call(void) \
> +static int ftrace_raw_init_event_##call(struct ftrace_event_call *dummy)\
> { \
> int id; \
> \
> diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
> index 6c81f9c..5d0a324 100644
> --- a/kernel/trace/trace_events.c
> +++ b/kernel/trace/trace_events.c
> @@ -60,9 +60,7 @@ err:
> }
> EXPORT_SYMBOL_GPL(trace_define_field);
>
> -#ifdef CONFIG_MODULES
> -
> -static void trace_destroy_fields(struct ftrace_event_call *call)
> +void trace_destroy_fields(struct ftrace_event_call *call)
> {
> struct ftrace_event_field *field, *next;
>
> @@ -74,8 +72,6 @@ static void trace_destroy_fields(struct ftrace_event_call *call)
> }
> }
>
> -#endif /* CONFIG_MODULES */
> -
> static void ftrace_event_enable_disable(struct ftrace_event_call *call,
> int enable)
> {
> @@ -84,14 +80,14 @@ static void ftrace_event_enable_disable(struct ftrace_event_call *call,
> if (call->enabled) {
> call->enabled = 0;
> tracing_stop_cmdline_record();
> - call->unregfunc();
> + call->unregfunc(call);
> }
> break;
> case 1:
> if (!call->enabled) {
> call->enabled = 1;
> tracing_start_cmdline_record();
> - call->regfunc();
> + call->regfunc(call);

Cute.

> }
> break;
> }
> @@ -558,7 +554,7 @@ event_format_read(struct file *filp, char __user *ubuf, size_t cnt,
> trace_seq_printf(s, "format:\n");
> trace_write_header(s);
>
> - r = call->show_format(s);
> + r = call->show_format(call, s);
> if (!r) {
> /*
> * ug! The format output is bigger than a PAGE!!
> @@ -905,7 +901,7 @@ event_create_dir(struct ftrace_event_call *call, struct dentry *d_events,
> d_events = event_subsystem_dir(call->system, d_events);
>
> if (call->raw_init) {
> - ret = call->raw_init();
> + ret = call->raw_init(call);
> if (ret < 0) {
> pr_warning("Could not initialize trace point"
> " events/%s\n", call->name);
> @@ -929,7 +925,7 @@ event_create_dir(struct ftrace_event_call *call, struct dentry *d_events,
> id);
>
> if (call->define_fields) {
> - ret = call->define_fields();
> + ret = call->define_fields(call);
> if (ret < 0) {
> pr_warning("Could not initialize trace point"
> " events/%s\n", call->name);
> @@ -949,6 +945,36 @@ event_create_dir(struct ftrace_event_call *call, struct dentry *d_events,
> return 0;
> }
>
> +/* Add an additional event_call dynamically */
> +int trace_add_event_call(struct ftrace_event_call *call)
> +{
> + struct dentry *d_events;
> +
> + if (!call->name)
> + return -EINVAL;
> +
> + d_events = event_trace_events_dir();
> + if (!d_events)
> + return -ENOENT;
> +
> + list_add(&call->list, &ftrace_events);

ftrace_events needs to be protected by the event_mutex.

> + return event_create_dir(call, d_events, &ftrace_event_id_fops,
> + &ftrace_enable_fops, &ftrace_event_filter_fops,
> + &ftrace_event_format_fops);
> +}
> +
> +/* Remove an event_call */
> +void trace_remove_event_call(struct ftrace_event_call *event_call)
> +{
> + ftrace_event_enable_disable(event_call, 0);
> + if (event_call->event)
> + unregister_ftrace_event(event_call->event);
> + debugfs_remove_recursive(event_call->dir);
> + list_del(&event_call->list);

Same here.

> + trace_destroy_fields(event_call);
> + destroy_preds(event_call);
> +}
> +
> #define for_each_event(event, start, end) \
> for (event = start; \
> (unsigned long)event < (unsigned long)end; \
> @@ -1053,13 +1079,7 @@ static void trace_module_remove_events(struct module *mod)
> list_for_each_entry_safe(call, p, &ftrace_events, list) {
> if (call->mod == mod) {
> found = true;
> - ftrace_event_enable_disable(call, 0);
> - if (call->event)
> - unregister_ftrace_event(call->event);
> - debugfs_remove_recursive(call->dir);
> - list_del(&call->list);
> - trace_destroy_fields(call);
> - destroy_preds(call);
> + trace_remove_event_call(call);

We'll need a version that does not take the event_mutex, because it is
held at this point.

-- Steve

> }
> }
>
> diff --git a/kernel/trace/trace_export.c b/kernel/trace/trace_export.c
> index d06cf89..7cee79d 100644
> --- a/kernel/trace/trace_export.c
> +++ b/kernel/trace/trace_export.c
> @@ -60,7 +60,7 @@ extern void __bad_type_size(void);
> #undef TRACE_EVENT_FORMAT
> #define TRACE_EVENT_FORMAT(call, proto, args, fmt, tstruct, tpfmt) \
> static int \
> -ftrace_format_##call(struct trace_seq *s) \
> +ftrace_format_##call(struct ftrace_event_call *dummy, struct trace_seq *s)\
> { \
> struct args field; \
> int ret; \
> @@ -76,7 +76,7 @@ ftrace_format_##call(struct trace_seq *s) \
> #define TRACE_EVENT_FORMAT_NOFILTER(call, proto, args, fmt, tstruct, \
> tpfmt) \
> static int \
> -ftrace_format_##call(struct trace_seq *s) \
> +ftrace_format_##call(struct ftrace_event_call *dummy, struct trace_seq *s)\
> { \
> struct args field; \
> int ret; \
> @@ -115,10 +115,16 @@ ftrace_format_##call(struct trace_seq *s) \
> #define TRACE_FIELD_SPECIAL(type_item, item, len, cmd) \
> cmd;
>
> +static int ftrace_raw_init_event(struct ftrace_event_call *event_call)
> +{
> + INIT_LIST_HEAD(&event_call->fields);
> + init_preds(event_call);
> + return 0;
> +}
> +
> #undef TRACE_EVENT_FORMAT
> #define TRACE_EVENT_FORMAT(call, proto, args, fmt, tstruct, tpfmt) \
> -int ftrace_define_fields_##call(void); \
> -static int ftrace_raw_init_event_##call(void); \
> +int ftrace_define_fields_##call(struct ftrace_event_call *c); \
> \
> struct ftrace_event_call __used \
> __attribute__((__aligned__(4))) \
> @@ -126,16 +132,10 @@ __attribute__((section("_ftrace_events"))) event_##call = { \
> .name = #call, \
> .id = proto, \
> .system = __stringify(TRACE_SYSTEM), \
> - .raw_init = ftrace_raw_init_event_##call, \
> + .raw_init = ftrace_raw_init_event, \
> .show_format = ftrace_format_##call, \
> .define_fields = ftrace_define_fields_##call, \
> -}; \
> -static int ftrace_raw_init_event_##call(void) \
> -{ \
> - INIT_LIST_HEAD(&event_##call.fields); \
> - init_preds(&event_##call); \
> - return 0; \
> -} \
> +};
>
> #undef TRACE_EVENT_FORMAT_NOFILTER
> #define TRACE_EVENT_FORMAT_NOFILTER(call, proto, args, fmt, tstruct, \
> @@ -182,9 +182,8 @@ __attribute__((section("_ftrace_events"))) event_##call = { \
> #undef TRACE_EVENT_FORMAT
> #define TRACE_EVENT_FORMAT(call, proto, args, fmt, tstruct, tpfmt) \
> int \
> -ftrace_define_fields_##call(void) \
> +ftrace_define_fields_##call(struct ftrace_event_call *event_call) \
> { \
> - struct ftrace_event_call *event_call = &event_##call; \
> struct args field; \
> int ret; \
> \
>
>
> --
> Masami Hiramatsu
>
> Software Engineer
> Hitachi Computer Products (America), Inc.
> Software Solutions Division
>
> e-mail: mhiramat@redhat.com
>


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