tracing: Add TRACE_CUSTOM_EVENT() macro
authorSteven Rostedt (Google) <rostedt@goodmis.org>
Thu, 3 Mar 2022 22:05:34 +0000 (17:05 -0500)
committerSteven Rostedt (Google) <rostedt@goodmis.org>
Fri, 11 Mar 2022 16:49:24 +0000 (11:49 -0500)
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>
include/linux/trace_events.h
include/trace/define_custom_trace.h [new file with mode: 0644]
include/trace/trace_custom_events.h [new file with mode: 0644]
samples/trace_events/Makefile
samples/trace_events/trace_custom_sched.c
samples/trace_events/trace_custom_sched.h [new file with mode: 0644]

index 70c069a..9b09fd6 100644 (file)
@@ -315,6 +315,7 @@ enum {
        TRACE_EVENT_FL_KPROBE_BIT,
        TRACE_EVENT_FL_UPROBE_BIT,
        TRACE_EVENT_FL_EPROBE_BIT,
+       TRACE_EVENT_FL_CUSTOM_BIT,
 };
 
 /*
@@ -328,6 +329,9 @@ enum {
  *  KPROBE        - Event is a kprobe
  *  UPROBE        - Event is a uprobe
  *  EPROBE        - Event is an event probe
+ *  CUSTOM        - Event is a custom event (to be attached to an exsiting tracepoint)
+ *                   This is set when the custom event has not been attached
+ *                   to a tracepoint yet, then it is cleared when it is.
  */
 enum {
        TRACE_EVENT_FL_FILTERED         = (1 << TRACE_EVENT_FL_FILTERED_BIT),
@@ -339,6 +343,7 @@ enum {
        TRACE_EVENT_FL_KPROBE           = (1 << TRACE_EVENT_FL_KPROBE_BIT),
        TRACE_EVENT_FL_UPROBE           = (1 << TRACE_EVENT_FL_UPROBE_BIT),
        TRACE_EVENT_FL_EPROBE           = (1 << TRACE_EVENT_FL_EPROBE_BIT),
+       TRACE_EVENT_FL_CUSTOM           = (1 << TRACE_EVENT_FL_CUSTOM_BIT),
 };
 
 #define TRACE_EVENT_FL_UKPROBE (TRACE_EVENT_FL_KPROBE | TRACE_EVENT_FL_UPROBE)
@@ -440,7 +445,9 @@ static inline bool bpf_prog_array_valid(struct trace_event_call *call)
 static inline const char *
 trace_event_name(struct trace_event_call *call)
 {
-       if (call->flags & TRACE_EVENT_FL_TRACEPOINT)
+       if (call->flags & TRACE_EVENT_FL_CUSTOM)
+               return call->name;
+       else if (call->flags & TRACE_EVENT_FL_TRACEPOINT)
                return call->tp ? call->tp->name : NULL;
        else
                return call->name;
@@ -901,3 +908,18 @@ perf_trace_buf_submit(void *raw_data, int size, int rctx, u16 type,
 #endif
 
 #endif /* _LINUX_TRACE_EVENT_H */
+
+/*
+ * Note: we keep the TRACE_CUSTOM_EVENT outside the include file ifdef protection.
+ *  This is due to the way trace custom events work. If a file includes two
+ *  trace event headers under one "CREATE_CUSTOM_TRACE_EVENTS" the first include
+ *  will override the TRACE_CUSTOM_EVENT and break the second include.
+ */
+
+#ifndef TRACE_CUSTOM_EVENT
+
+#define DECLARE_CUSTOM_EVENT_CLASS(name, proto, args, tstruct, assign, print)
+#define DEFINE_CUSTOM_EVENT(template, name, proto, args)
+#define TRACE_CUSTOM_EVENT(name, proto, args, struct, assign, print)
+
+#endif /* ifdef TRACE_CUSTOM_EVENT (see note above) */
diff --git a/include/trace/define_custom_trace.h b/include/trace/define_custom_trace.h
new file mode 100644 (file)
index 0000000..5827a4c
--- /dev/null
@@ -0,0 +1,77 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Trace files that want to automate creation of all tracepoints defined
+ * in their file should include this file. The following are macros that the
+ * trace file may define:
+ *
+ * TRACE_SYSTEM defines the system the tracepoint is for
+ *
+ * TRACE_INCLUDE_FILE if the file name is something other than TRACE_SYSTEM.h
+ *     This macro may be defined to tell define_trace.h what file to include.
+ *     Note, leave off the ".h".
+ *
+ * TRACE_INCLUDE_PATH if the path is something other than core kernel include/trace
+ *     then this macro can define the path to use. Note, the path is relative to
+ *     define_trace.h, not the file including it. Full path names for out of tree
+ *     modules must be used.
+ */
+
+#ifdef CREATE_CUSTOM_TRACE_EVENTS
+
+/* Prevent recursion */
+#undef CREATE_CUSTOM_TRACE_EVENTS
+
+#include <linux/stringify.h>
+
+#undef TRACE_CUSTOM_EVENT
+#define TRACE_CUSTOM_EVENT(name, proto, args, tstruct, assign, print)
+
+#undef DEFINE_CUSTOM_EVENT
+#define DEFINE_CUSTOM_EVENT(template, name, proto, args)
+
+#undef TRACE_INCLUDE
+#undef __TRACE_INCLUDE
+
+#ifndef TRACE_INCLUDE_FILE
+# define TRACE_INCLUDE_FILE TRACE_SYSTEM
+# define UNDEF_TRACE_INCLUDE_FILE
+#endif
+
+#ifndef TRACE_INCLUDE_PATH
+# define __TRACE_INCLUDE(system) <trace/events/system.h>
+# define UNDEF_TRACE_INCLUDE_PATH
+#else
+# define __TRACE_INCLUDE(system) __stringify(TRACE_INCLUDE_PATH/system.h)
+#endif
+
+# define TRACE_INCLUDE(system) __TRACE_INCLUDE(system)
+
+/* Let the trace headers be reread */
+#define TRACE_CUSTOM_MULTI_READ
+
+#include TRACE_INCLUDE(TRACE_INCLUDE_FILE)
+
+#ifdef TRACEPOINTS_ENABLED
+#include <trace/trace_custom_events.h>
+#endif
+
+#undef TRACE_CUSTOM_EVENT
+#undef DECLARE_CUSTOM_EVENT_CLASS
+#undef DEFINE_CUSTOM_EVENT
+#undef TRACE_CUSTOM_MULTI_READ
+
+/* Only undef what we defined in this file */
+#ifdef UNDEF_TRACE_INCLUDE_FILE
+# undef TRACE_INCLUDE_FILE
+# undef UNDEF_TRACE_INCLUDE_FILE
+#endif
+
+#ifdef UNDEF_TRACE_INCLUDE_PATH
+# undef TRACE_INCLUDE_PATH
+# undef UNDEF_TRACE_INCLUDE_PATH
+#endif
+
+/* We may be processing more files */
+#define CREATE_CUSTOM_TRACE_POINTS
+
+#endif /* CREATE_CUSTOM_TRACE_POINTS */
diff --git a/include/trace/trace_custom_events.h b/include/trace/trace_custom_events.h
new file mode 100644 (file)
index 0000000..b567c72
--- /dev/null
@@ -0,0 +1,221 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * This is similar to the trace_events.h file, but is to only
+ * create custom trace events to be attached to existing tracepoints.
+ * Where as the TRACE_EVENT() macro (from trace_events.h) will create
+ * both the trace event and the tracepoint it will attach the event to,
+ * TRACE_CUSTOM_EVENT() is to create only a custom version of an existing
+ * trace event (created by TRACE_EVENT() or DEFINE_EVENT()), and will
+ * be placed in the "custom" system.
+ */
+
+#include <linux/trace_events.h>
+
+/* All custom events are placed in the custom group */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM custom
+
+#ifndef TRACE_SYSTEM_VAR
+#define TRACE_SYSTEM_VAR TRACE_SYSTEM
+#endif
+
+/* The init stage creates the system string and enum mappings */
+
+#include "stages/init.h"
+
+#undef TRACE_CUSTOM_EVENT
+#define TRACE_CUSTOM_EVENT(name, proto, args, tstruct, assign, print) \
+       DECLARE_CUSTOM_EVENT_CLASS(name,                              \
+                            PARAMS(proto),                    \
+                            PARAMS(args),                     \
+                            PARAMS(tstruct),                  \
+                            PARAMS(assign),                   \
+                            PARAMS(print));                   \
+       DEFINE_CUSTOM_EVENT(name, name, PARAMS(proto), PARAMS(args));
+
+/* Stage 1 creates the structure of the recorded event layout */
+
+#include "stages/stage1_defines.h"
+
+#undef DECLARE_CUSTOM_EVENT_CLASS
+#define DECLARE_CUSTOM_EVENT_CLASS(name, proto, args, tstruct, assign, print) \
+       struct trace_custom_event_raw_##name {                          \
+               struct trace_entry      ent;                            \
+               tstruct                                                 \
+               char                    __data[];                       \
+       };                                                              \
+                                                                       \
+       static struct trace_event_class custom_event_class_##name;
+
+#undef DEFINE_CUSTOM_EVENT
+#define DEFINE_CUSTOM_EVENT(template, name, proto, args)       \
+       static struct trace_event_call  __used                  \
+       __attribute__((__aligned__(4))) custom_event_##name
+
+#include TRACE_INCLUDE(TRACE_INCLUDE_FILE)
+
+/* Stage 2 creates the custom class */
+
+#include "stages/stage2_defines.h"
+
+#undef DECLARE_CUSTOM_EVENT_CLASS
+#define DECLARE_CUSTOM_EVENT_CLASS(call, proto, args, tstruct, assign, print)  \
+       struct trace_custom_event_data_offsets_##call {                 \
+               tstruct;                                                \
+       };
+
+#undef DEFINE_CUSTOM_EVENT
+#define DEFINE_CUSTOM_EVENT(template, name, proto, args)
+
+#include TRACE_INCLUDE(TRACE_INCLUDE_FILE)
+
+/* Stage 3 create the way to print the custom event */
+
+#include "stages/stage3_defines.h"
+
+#undef DECLARE_CUSTOM_EVENT_CLASS
+#define DECLARE_CUSTOM_EVENT_CLASS(call, proto, args, tstruct, assign, print) \
+static notrace enum print_line_t                                       \
+trace_custom_raw_output_##call(struct trace_iterator *iter, int flags, \
+                       struct trace_event *trace_event)                \
+{                                                                      \
+       struct trace_seq *s = &iter->seq;                               \
+       struct trace_seq __maybe_unused *p = &iter->tmp_seq;            \
+       struct trace_custom_event_raw_##call *field;                    \
+       int ret;                                                        \
+                                                                       \
+       field = (typeof(field))iter->ent;                               \
+                                                                       \
+       ret = trace_raw_output_prep(iter, trace_event);                 \
+       if (ret != TRACE_TYPE_HANDLED)                                  \
+               return ret;                                             \
+                                                                       \
+       trace_event_printf(iter, print);                                \
+                                                                       \
+       return trace_handle_return(s);                                  \
+}                                                                      \
+static struct trace_event_functions trace_custom_event_type_funcs_##call = { \
+       .trace                  = trace_custom_raw_output_##call,       \
+};
+
+#include TRACE_INCLUDE(TRACE_INCLUDE_FILE)
+
+/* Stage 4 creates the offset layout for the fields */
+
+#include "stages/stage4_defines.h"
+
+#undef DECLARE_CUSTOM_EVENT_CLASS
+#define DECLARE_CUSTOM_EVENT_CLASS(call, proto, args, tstruct, func, print)    \
+static struct trace_event_fields trace_custom_event_fields_##call[] = {        \
+       tstruct                                                         \
+       {} };
+
+#include TRACE_INCLUDE(TRACE_INCLUDE_FILE)
+
+/* Stage 5 creates the helper function for dynamic fields */
+
+#include "stages/stage5_defines.h"
+
+#undef DECLARE_CUSTOM_EVENT_CLASS
+#define DECLARE_CUSTOM_EVENT_CLASS(call, proto, args, tstruct, assign, print) \
+static inline notrace int trace_custom_event_get_offsets_##call(       \
+       struct trace_custom_event_data_offsets_##call *__data_offsets, proto) \
+{                                                                      \
+       int __data_size = 0;                                            \
+       int __maybe_unused __item_length;                               \
+       struct trace_custom_event_raw_##call __maybe_unused *entry;     \
+                                                                       \
+       tstruct;                                                        \
+                                                                       \
+       return __data_size;                                             \
+}
+
+#include TRACE_INCLUDE(TRACE_INCLUDE_FILE)
+
+/* Stage 6 creates the probe function that records the event */
+
+#include "stages/stage6_defines.h"
+
+#undef DECLARE_CUSTOM_EVENT_CLASS
+#define DECLARE_CUSTOM_EVENT_CLASS(call, proto, args, tstruct, assign, print) \
+                                                                       \
+static notrace void                                                    \
+trace_custom_event_raw_event_##call(void *__data, proto)               \
+{                                                                      \
+       struct trace_event_file *trace_file = __data;                   \
+       struct trace_custom_event_data_offsets_##call __maybe_unused __data_offsets; \
+       struct trace_event_buffer fbuffer;                              \
+       struct trace_custom_event_raw_##call *entry;                    \
+       int __data_size;                                                \
+                                                                       \
+       if (trace_trigger_soft_disabled(trace_file))                    \
+               return;                                                 \
+                                                                       \
+       __data_size = trace_custom_event_get_offsets_##call(&__data_offsets, args); \
+                                                                       \
+       entry = trace_event_buffer_reserve(&fbuffer, trace_file,        \
+                                sizeof(*entry) + __data_size);         \
+                                                                       \
+       if (!entry)                                                     \
+               return;                                                 \
+                                                                       \
+       tstruct                                                         \
+                                                                       \
+       { assign; }                                                     \
+                                                                       \
+       trace_event_buffer_commit(&fbuffer);                            \
+}
+/*
+ * The ftrace_test_custom_probe is compiled out, it is only here as a build time check
+ * to make sure that if the tracepoint handling changes, the ftrace probe will
+ * fail to compile unless it too is updated.
+ */
+
+#undef DEFINE_CUSTOM_EVENT
+#define DEFINE_CUSTOM_EVENT(template, call, proto, args)               \
+static inline void ftrace_test_custom_probe_##call(void)               \
+{                                                                      \
+       check_trace_callback_type_##call(trace_custom_event_raw_event_##template); \
+}
+
+#include TRACE_INCLUDE(TRACE_INCLUDE_FILE)
+
+/* Stage 7 creates the actual class and event structure for the custom event */
+
+#include "stages/stage7_defines.h"
+
+#undef DECLARE_CUSTOM_EVENT_CLASS
+#define DECLARE_CUSTOM_EVENT_CLASS(call, proto, args, tstruct, assign, print) \
+static char custom_print_fmt_##call[] = print;                                 \
+static struct trace_event_class __used __refdata custom_event_class_##call = { \
+       .system                 = TRACE_SYSTEM_STRING,                  \
+       .fields_array           = trace_custom_event_fields_##call,             \
+       .fields                 = LIST_HEAD_INIT(custom_event_class_##call.fields),\
+       .raw_init               = trace_event_raw_init,                 \
+       .probe                  = trace_custom_event_raw_event_##call,  \
+       .reg                    = trace_event_reg,                      \
+};
+
+#undef DEFINE_CUSTOM_EVENT
+#define DEFINE_CUSTOM_EVENT(template, call, proto, args)               \
+                                                                       \
+static struct trace_event_call __used custom_event_##call = {          \
+       .name                   = #call,                                \
+       .class                  = &custom_event_class_##template,       \
+       .event.funcs            = &trace_custom_event_type_funcs_##template, \
+       .print_fmt              = custom_print_fmt_##template,          \
+       .flags                  = TRACE_EVENT_FL_CUSTOM,                \
+};                                                                     \
+static inline int trace_custom_event_##call##_update(struct tracepoint *tp) \
+{                                                                      \
+       if (tp->name && strcmp(tp->name, #call) == 0) {                 \
+               custom_event_##call.tp = tp;                            \
+               custom_event_##call.flags = TRACE_EVENT_FL_TRACEPOINT;  \
+               return 1;                                               \
+       }                                                               \
+       return 0;                                                       \
+}                                                                      \
+static struct trace_event_call __used                                  \
+__section("_ftrace_events") *__custom_event_##call = &custom_event_##call
+
+#include TRACE_INCLUDE(TRACE_INCLUDE_FILE)
index e98afc4..b3808bb 100644 (file)
@@ -11,7 +11,7 @@
 # Here trace-events-sample.c does the CREATE_TRACE_POINTS.
 #
 CFLAGS_trace-events-sample.o := -I$(src)
+CFLAGS_trace_custom_sched.o := -I$(src)
 
 obj-$(CONFIG_SAMPLE_TRACE_EVENTS) += trace-events-sample.o
-
 obj-$(CONFIG_SAMPLE_TRACE_CUSTOM_EVENTS) += trace_custom_sched.o
index 70a12c3..b99d9ab 100644 (file)
 #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);
diff --git a/samples/trace_events/trace_custom_sched.h b/samples/trace_events/trace_custom_sched.h
new file mode 100644 (file)
index 0000000..a3d14de
--- /dev/null
@@ -0,0 +1,95 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/*
+ * Like the headers that use TRACE_EVENT(), the TRACE_CUSTOM_EVENT()
+ * needs a header that allows for multiple inclusions.
+ *
+ * Test for a unique name (here we have _TRACE_CUSTOM_SCHED_H),
+ * also allowing to continue if TRACE_CUSTOM_MULTI_READ is defined.
+ */
+#if !defined(_TRACE_CUSTOM_SCHED_H) || defined(TRACE_CUSTOM_MULTI_READ)
+#define _TRACE_CUSTOM_SCHED_H
+
+/* Include linux/trace_events.h for initial defines of TRACE_CUSTOM_EVENT() */
+#include <linux/trace_events.h>
+
+/*
+ * TRACE_CUSTOM_EVENT() is just like TRACE_EVENT(). The first parameter
+ * is the event name of an existing event where the TRACE_EVENT has been included
+ * in the C file before including this file.
+ */
+TRACE_CUSTOM_EVENT(sched_switch,
+
+       /*
+        * The TP_PROTO() and TP_ARGS must match the trace event
+        * that the custom event is using.
+        */
+       TP_PROTO(bool preempt,
+                struct task_struct *prev,
+                struct task_struct *next),
+
+       TP_ARGS(preempt, prev, next),
+
+       /*
+        * The next fields are where the customization happens.
+        * The TP_STRUCT__entry() defines what will be recorded
+        * in the ring buffer when the custom event triggers.
+        *
+        * The rest is just like the TRACE_EVENT() macro except that
+        * it uses the custom entry.
+        */
+       TP_STRUCT__entry(
+               __field(        unsigned short,         prev_prio       )
+               __field(        unsigned short,         next_prio       )
+               __field(        pid_t,  next_pid                        )
+       ),
+
+       TP_fast_assign(
+               __entry->prev_prio      = prev->prio;
+               __entry->next_pid       = next->pid;
+               __entry->next_prio      = next->prio;
+       ),
+
+       TP_printk("prev_prio=%d next_pid=%d next_prio=%d",
+                 __entry->prev_prio, __entry->next_pid, __entry->next_prio)
+)
+
+
+TRACE_CUSTOM_EVENT(sched_waking,
+
+       TP_PROTO(struct task_struct *p),
+
+       TP_ARGS(p),
+
+       TP_STRUCT__entry(
+               __field(        pid_t,                  pid     )
+               __field(        unsigned short,         prio    )
+       ),
+
+       TP_fast_assign(
+               __entry->pid    = p->pid;
+               __entry->prio   = p->prio;
+       ),
+
+       TP_printk("pid=%d prio=%d", __entry->pid, __entry->prio)
+)
+#endif
+/*
+ * Just like the headers that create TRACE_EVENTs, the below must
+ * be outside the protection of the above #if block.
+ */
+
+/*
+ * It is required that the Makefile includes:
+ *    CFLAGS_<c_file>.o := -I$(src)
+ */
+#undef TRACE_INCLUDE_PATH
+#undef TRACE_INCLUDE_FILE
+#define TRACE_INCLUDE_PATH .
+
+/*
+ * It is requred that the TRACE_INCLUDE_FILE be the same
+ * as this file without the ".h".
+ */
+#define TRACE_INCLUDE_FILE trace_custom_sched
+#include <trace/define_custom_trace.h>