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author | Steven Rostedt (Google) <rostedt@goodmis.org> | 2022-03-03 17:05:34 -0500 |
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committer | Steven Rostedt (Google) <rostedt@goodmis.org> | 2022-03-11 11:49:24 -0500 |
commit | 3a73333fb370f7b65de9d94c53df503642bda789 (patch) | |
tree | c3bafc1a059c00507daabd3ba27ea4c3c3a92bd9 /samples/trace_events/trace_custom_sched.c | |
parent | af6b9668e85ffd1502aada8036ccbf4dbd481708 (diff) | |
download | linux-3a73333fb370f7b65de9d94c53df503642bda789.tar.bz2 |
tracing: Add TRACE_CUSTOM_EVENT() macro
To make it really easy to add custom events from modules, add a
TRACE_CUSTOM_EVENT() macro that acts just like the TRACE_EVENT() macro,
but creates a custom event to an already existing tracepoint.
The trace_custom_sched.[ch] has been updated to use this new macro to show
how simple it is.
Link: https://lkml.kernel.org/r/20220303220625.738622494@goodmis.org
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Diffstat (limited to 'samples/trace_events/trace_custom_sched.c')
-rw-r--r-- | samples/trace_events/trace_custom_sched.c | 259 |
1 files changed, 24 insertions, 235 deletions
diff --git a/samples/trace_events/trace_custom_sched.c b/samples/trace_events/trace_custom_sched.c index 70a12c32ff99..b99d9ab7db85 100644 --- a/samples/trace_events/trace_custom_sched.c +++ b/samples/trace_events/trace_custom_sched.c @@ -11,256 +11,45 @@ #include <linux/version.h> #include <linux/module.h> #include <linux/sched.h> -#include <trace/events/sched.h> - -#define THIS_SYSTEM "custom_sched" - -#define SCHED_PRINT_FMT \ - C("prev_prio=%d next_pid=%d next_prio=%d", REC->prev_prio, REC->next_pid, \ - REC->next_prio) - -#define SCHED_WAKING_FMT \ - C("pid=%d prio=%d", REC->pid, REC->prio) - -#undef C -#define C(a, b...) a, b - -static struct trace_event_fields sched_switch_fields[] = { - { - .type = "unsigned short", - .name = "prev_prio", - .size = sizeof(short), - .align = __alignof__(short), - .is_signed = 0, - .filter_type = FILTER_OTHER, - }, - { - .type = "unsigned short", - .name = "next_prio", - .size = sizeof(short), - .align = __alignof__(short), - .is_signed = 0, - .filter_type = FILTER_OTHER, - }, - { - .type = "unsigned int", - .name = "next_prio", - .size = sizeof(int), - .align = __alignof__(int), - .is_signed = 0, - .filter_type = FILTER_OTHER, - }, - {} -}; - -struct sched_event { - struct trace_entry ent; - unsigned short prev_prio; - unsigned short next_prio; - unsigned int next_pid; -}; - -static struct trace_event_fields sched_waking_fields[] = { - { - .type = "unsigned int", - .name = "pid", - .size = sizeof(int), - .align = __alignof__(int), - .is_signed = 0, - .filter_type = FILTER_OTHER, - }, - { - .type = "unsigned short", - .name = "prio", - .size = sizeof(short), - .align = __alignof__(short), - .is_signed = 0, - .filter_type = FILTER_OTHER, - }, - {} -}; - -struct wake_event { - struct trace_entry ent; - unsigned int pid; - unsigned short prio; -}; - -static void sched_switch_probe(void *data, bool preempt, struct task_struct *prev, - struct task_struct *next) -{ - struct trace_event_file *trace_file = data; - struct trace_event_buffer fbuffer; - struct sched_event *entry; - - if (trace_trigger_soft_disabled(trace_file)) - return; - - entry = trace_event_buffer_reserve(&fbuffer, trace_file, - sizeof(*entry)); - - if (!entry) - return; - - entry->prev_prio = prev->prio; - entry->next_prio = next->prio; - entry->next_pid = next->pid; - - trace_event_buffer_commit(&fbuffer); -} - -static struct trace_event_class sched_switch_class = { - .system = THIS_SYSTEM, - .reg = trace_event_reg, - .fields_array = sched_switch_fields, - .fields = LIST_HEAD_INIT(sched_switch_class.fields), - .probe = sched_switch_probe, -}; - -static void sched_waking_probe(void *data, struct task_struct *t) -{ - struct trace_event_file *trace_file = data; - struct trace_event_buffer fbuffer; - struct wake_event *entry; - - if (trace_trigger_soft_disabled(trace_file)) - return; - - entry = trace_event_buffer_reserve(&fbuffer, trace_file, - sizeof(*entry)); - - if (!entry) - return; - - entry->prio = t->prio; - entry->pid = t->pid; - - trace_event_buffer_commit(&fbuffer); -} - -static struct trace_event_class sched_waking_class = { - .system = THIS_SYSTEM, - .reg = trace_event_reg, - .fields_array = sched_waking_fields, - .fields = LIST_HEAD_INIT(sched_waking_class.fields), - .probe = sched_waking_probe, -}; - -static enum print_line_t sched_switch_output(struct trace_iterator *iter, int flags, - struct trace_event *trace_event) -{ - struct trace_seq *s = &iter->seq; - struct sched_event *REC = (struct sched_event *)iter->ent; - int ret; - - ret = trace_raw_output_prep(iter, trace_event); - if (ret != TRACE_TYPE_HANDLED) - return ret; - - trace_seq_printf(s, SCHED_PRINT_FMT); - trace_seq_putc(s, '\n'); - return trace_handle_return(s); -} - -static struct trace_event_functions sched_switch_funcs = { - .trace = sched_switch_output, -}; - -static enum print_line_t sched_waking_output(struct trace_iterator *iter, int flags, - struct trace_event *trace_event) -{ - struct trace_seq *s = &iter->seq; - struct wake_event *REC = (struct wake_event *)iter->ent; - int ret; - - ret = trace_raw_output_prep(iter, trace_event); - if (ret != TRACE_TYPE_HANDLED) - return ret; - - trace_seq_printf(s, SCHED_WAKING_FMT); - trace_seq_putc(s, '\n'); - - return trace_handle_return(s); -} - -static struct trace_event_functions sched_waking_funcs = { - .trace = sched_waking_output, -}; - -#undef C -#define C(a, b...) #a "," __stringify(b) +/* + * Must include the event header that the custom event will attach to, + * from the C file, and not in the custom header file. + */ +#include <trace/events/sched.h> -static struct trace_event_call sched_switch_call = { - .class = &sched_switch_class, - .event = { - .funcs = &sched_switch_funcs, - }, - .print_fmt = SCHED_PRINT_FMT, - .module = THIS_MODULE, - .flags = TRACE_EVENT_FL_TRACEPOINT, -}; +/* Declare CREATE_CUSTOM_TRACE_EVENTS before including custom header */ +#define CREATE_CUSTOM_TRACE_EVENTS -static struct trace_event_call sched_waking_call = { - .class = &sched_waking_class, - .event = { - .funcs = &sched_waking_funcs, - }, - .print_fmt = SCHED_WAKING_FMT, - .module = THIS_MODULE, - .flags = TRACE_EVENT_FL_TRACEPOINT, -}; +#include "trace_custom_sched.h" +/* + * As the trace events are not exported to modules, the use of + * for_each_kernel_tracepoint() is needed to find the trace event + * to attach to. The fct() function below, is a callback that + * will be called for every event. + * + * Helper functions are created by the TRACE_CUSTOM_EVENT() macro + * update the event. Those are of the form: + * + * trace_custom_event_<event>_update() + * + * Where <event> is the event to attach. + */ static void fct(struct tracepoint *tp, void *priv) { - if (tp->name && strcmp(tp->name, "sched_switch") == 0) - sched_switch_call.tp = tp; - else if (tp->name && strcmp(tp->name, "sched_waking") == 0) - sched_waking_call.tp = tp; -} - -static int add_event(struct trace_event_call *call) -{ - int ret; - - ret = register_trace_event(&call->event); - if (WARN_ON(!ret)) - return -ENODEV; - - ret = trace_add_event_call(call); - if (WARN_ON(ret)) - unregister_trace_event(&call->event); - - return ret; + trace_custom_event_sched_switch_update(tp); + trace_custom_event_sched_waking_update(tp); } static int __init trace_sched_init(void) { - int ret; - - check_trace_callback_type_sched_switch(sched_switch_probe); - check_trace_callback_type_sched_waking(sched_waking_probe); - for_each_kernel_tracepoint(fct, NULL); - - ret = add_event(&sched_switch_call); - if (ret) - return ret; - - ret = add_event(&sched_waking_call); - if (ret) - trace_remove_event_call(&sched_switch_call); - - return ret; + return 0; } static void __exit trace_sched_exit(void) { - trace_set_clr_event(THIS_SYSTEM, "sched_switch", 0); - trace_set_clr_event(THIS_SYSTEM, "sched_waking", 0); - - trace_remove_event_call(&sched_switch_call); - trace_remove_event_call(&sched_waking_call); } module_init(trace_sched_init); |