[for-linus][PATCH 5/5] tracing: Consolidate trace() functions

From: Steven Rostedt
Date: Tue Feb 11 2020 - 08:50:02 EST


From: Tom Zanussi <zanussi@xxxxxxxxxx>

Move the checking, buffer reserve and buffer commit code in
synth_event_trace_start/end() into inline functions
__synth_event_trace_start/end() so they can also be used by
synth_event_trace() and synth_event_trace_array(), and then have all
those functions use them.

Also, change synth_event_trace_state.enabled to disabled so it only
needs to be set if the event is disabled, which is not normally the
case.

Link: http://lkml.kernel.org/r/b1f3108d0f450e58192955a300e31d0405ab4149.1581374549.git.zanussi@xxxxxxxxxx

Signed-off-by: Tom Zanussi <zanussi@xxxxxxxxxx>
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
---
include/linux/trace_events.h | 2 +-
kernel/trace/trace_events_hist.c | 220 ++++++++++++-------------------
2 files changed, 87 insertions(+), 135 deletions(-)

diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
index 67f528ecb9e5..21098298b49b 100644
--- a/include/linux/trace_events.h
+++ b/include/linux/trace_events.h
@@ -424,7 +424,7 @@ struct synth_event_trace_state {
struct synth_event *event;
unsigned int cur_field;
unsigned int n_u64;
- bool enabled;
+ bool disabled;
bool add_next;
bool add_name;
};
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 99a02168599b..65b54d6a1422 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -1791,6 +1791,60 @@ void synth_event_cmd_init(struct dynevent_cmd *cmd, char *buf, int maxlen)
}
EXPORT_SYMBOL_GPL(synth_event_cmd_init);

+static inline int
+__synth_event_trace_start(struct trace_event_file *file,
+ struct synth_event_trace_state *trace_state)
+{
+ int entry_size, fields_size = 0;
+ int ret = 0;
+
+ /*
+ * Normal event tracing doesn't get called at all unless the
+ * ENABLED bit is set (which attaches the probe thus allowing
+ * this code to be called, etc). Because this is called
+ * directly by the user, we don't have that but we still need
+ * to honor not logging when disabled. For the the iterated
+ * trace case, we save the enabed state upon start and just
+ * ignore the following data calls.
+ */
+ if (!(file->flags & EVENT_FILE_FL_ENABLED) ||
+ trace_trigger_soft_disabled(file)) {
+ trace_state->disabled = true;
+ ret = -ENOENT;
+ goto out;
+ }
+
+ trace_state->event = file->event_call->data;
+
+ fields_size = trace_state->event->n_u64 * sizeof(u64);
+
+ /*
+ * Avoid ring buffer recursion detection, as this event
+ * is being performed within another event.
+ */
+ trace_state->buffer = file->tr->array_buffer.buffer;
+ ring_buffer_nest_start(trace_state->buffer);
+
+ entry_size = sizeof(*trace_state->entry) + fields_size;
+ trace_state->entry = trace_event_buffer_reserve(&trace_state->fbuffer,
+ file,
+ entry_size);
+ if (!trace_state->entry) {
+ ring_buffer_nest_end(trace_state->buffer);
+ ret = -EINVAL;
+ }
+out:
+ return ret;
+}
+
+static inline void
+__synth_event_trace_end(struct synth_event_trace_state *trace_state)
+{
+ trace_event_buffer_commit(&trace_state->fbuffer);
+
+ ring_buffer_nest_end(trace_state->buffer);
+}
+
/**
* synth_event_trace - Trace a synthetic event
* @file: The trace_event_file representing the synthetic event
@@ -1812,69 +1866,38 @@ EXPORT_SYMBOL_GPL(synth_event_cmd_init);
*/
int synth_event_trace(struct trace_event_file *file, unsigned int n_vals, ...)
{
- struct trace_event_buffer fbuffer;
- struct synth_trace_event *entry;
- struct trace_buffer *buffer;
- struct synth_event *event;
+ struct synth_event_trace_state state;
unsigned int i, n_u64;
- int fields_size = 0;
va_list args;
- int ret = 0;
-
- /*
- * Normal event generation doesn't get called at all unless
- * the ENABLED bit is set (which attaches the probe thus
- * allowing this code to be called, etc). Because this is
- * called directly by the user, we don't have that but we
- * still need to honor not logging when disabled.
- */
- if (!(file->flags & EVENT_FILE_FL_ENABLED) ||
- trace_trigger_soft_disabled(file))
- return 0;
-
- event = file->event_call->data;
-
- if (n_vals != event->n_fields)
- return -EINVAL;
-
- fields_size = event->n_u64 * sizeof(u64);
-
- /*
- * Avoid ring buffer recursion detection, as this event
- * is being performed within another event.
- */
- buffer = file->tr->array_buffer.buffer;
- ring_buffer_nest_start(buffer);
+ int ret;

- entry = trace_event_buffer_reserve(&fbuffer, file,
- sizeof(*entry) + fields_size);
- if (!entry) {
- ret = -EINVAL;
- goto out;
+ ret = __synth_event_trace_start(file, &state);
+ if (ret) {
+ if (ret == -ENOENT)
+ ret = 0; /* just disabled, not really an error */
+ return ret;
}

va_start(args, n_vals);
- for (i = 0, n_u64 = 0; i < event->n_fields; i++) {
+ for (i = 0, n_u64 = 0; i < state.event->n_fields; i++) {
u64 val;

val = va_arg(args, u64);

- if (event->fields[i]->is_string) {
+ if (state.event->fields[i]->is_string) {
char *str_val = (char *)(long)val;
- char *str_field = (char *)&entry->fields[n_u64];
+ char *str_field = (char *)&state.entry->fields[n_u64];

strscpy(str_field, str_val, STR_VAR_LEN_MAX);
n_u64 += STR_VAR_LEN_MAX / sizeof(u64);
} else {
- entry->fields[n_u64] = val;
+ state.entry->fields[n_u64] = val;
n_u64++;
}
}
va_end(args);

- trace_event_buffer_commit(&fbuffer);
-out:
- ring_buffer_nest_end(buffer);
+ __synth_event_trace_end(&state);

return ret;
}
@@ -1901,62 +1924,31 @@ EXPORT_SYMBOL_GPL(synth_event_trace);
int synth_event_trace_array(struct trace_event_file *file, u64 *vals,
unsigned int n_vals)
{
- struct trace_event_buffer fbuffer;
- struct synth_trace_event *entry;
- struct trace_buffer *buffer;
- struct synth_event *event;
+ struct synth_event_trace_state state;
unsigned int i, n_u64;
- int fields_size = 0;
- int ret = 0;
-
- /*
- * Normal event generation doesn't get called at all unless
- * the ENABLED bit is set (which attaches the probe thus
- * allowing this code to be called, etc). Because this is
- * called directly by the user, we don't have that but we
- * still need to honor not logging when disabled.
- */
- if (!(file->flags & EVENT_FILE_FL_ENABLED) ||
- trace_trigger_soft_disabled(file))
- return 0;
-
- event = file->event_call->data;
-
- if (n_vals != event->n_fields)
- return -EINVAL;
-
- fields_size = event->n_u64 * sizeof(u64);
-
- /*
- * Avoid ring buffer recursion detection, as this event
- * is being performed within another event.
- */
- buffer = file->tr->array_buffer.buffer;
- ring_buffer_nest_start(buffer);
+ int ret;

- entry = trace_event_buffer_reserve(&fbuffer, file,
- sizeof(*entry) + fields_size);
- if (!entry) {
- ret = -EINVAL;
- goto out;
+ ret = __synth_event_trace_start(file, &state);
+ if (ret) {
+ if (ret == -ENOENT)
+ ret = 0; /* just disabled, not really an error */
+ return ret;
}

- for (i = 0, n_u64 = 0; i < event->n_fields; i++) {
- if (event->fields[i]->is_string) {
+ for (i = 0, n_u64 = 0; i < state.event->n_fields; i++) {
+ if (state.event->fields[i]->is_string) {
char *str_val = (char *)(long)vals[i];
- char *str_field = (char *)&entry->fields[n_u64];
+ char *str_field = (char *)&state.entry->fields[n_u64];

strscpy(str_field, str_val, STR_VAR_LEN_MAX);
n_u64 += STR_VAR_LEN_MAX / sizeof(u64);
} else {
- entry->fields[n_u64] = vals[i];
+ state.entry->fields[n_u64] = vals[i];
n_u64++;
}
}

- trace_event_buffer_commit(&fbuffer);
-out:
- ring_buffer_nest_end(buffer);
+ __synth_event_trace_end(&state);

return ret;
}
@@ -1993,55 +1985,17 @@ EXPORT_SYMBOL_GPL(synth_event_trace_array);
int synth_event_trace_start(struct trace_event_file *file,
struct synth_event_trace_state *trace_state)
{
- struct synth_trace_event *entry;
- int fields_size = 0;
- int ret = 0;
+ int ret;

- if (!trace_state) {
- ret = -EINVAL;
- goto out;
- }
+ if (!trace_state)
+ return -EINVAL;

memset(trace_state, '\0', sizeof(*trace_state));

- /*
- * Normal event tracing doesn't get called at all unless the
- * ENABLED bit is set (which attaches the probe thus allowing
- * this code to be called, etc). Because this is called
- * directly by the user, we don't have that but we still need
- * to honor not logging when disabled. For the the iterated
- * trace case, we save the enabed state upon start and just
- * ignore the following data calls.
- */
- if (!(file->flags & EVENT_FILE_FL_ENABLED) ||
- trace_trigger_soft_disabled(file)) {
- trace_state->enabled = false;
- goto out;
- }
-
- trace_state->enabled = true;
+ ret = __synth_event_trace_start(file, trace_state);
+ if (ret == -ENOENT)
+ ret = 0; /* just disabled, not really an error */

- trace_state->event = file->event_call->data;
-
- fields_size = trace_state->event->n_u64 * sizeof(u64);
-
- /*
- * Avoid ring buffer recursion detection, as this event
- * is being performed within another event.
- */
- trace_state->buffer = file->tr->array_buffer.buffer;
- ring_buffer_nest_start(trace_state->buffer);
-
- entry = trace_event_buffer_reserve(&trace_state->fbuffer, file,
- sizeof(*entry) + fields_size);
- if (!entry) {
- ring_buffer_nest_end(trace_state->buffer);
- ret = -EINVAL;
- goto out;
- }
-
- trace_state->entry = entry;
-out:
return ret;
}
EXPORT_SYMBOL_GPL(synth_event_trace_start);
@@ -2074,7 +2028,7 @@ static int __synth_event_add_val(const char *field_name, u64 val,
trace_state->add_next = true;
}

- if (!trace_state->enabled)
+ if (trace_state->disabled)
goto out;

event = trace_state->event;
@@ -2209,9 +2163,7 @@ int synth_event_trace_end(struct synth_event_trace_state *trace_state)
if (!trace_state)
return -EINVAL;

- trace_event_buffer_commit(&trace_state->fbuffer);
-
- ring_buffer_nest_end(trace_state->buffer);
+ __synth_event_trace_end(trace_state);

return 0;
}
--
2.24.1