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Subject[PATCH v3 4/7] tracing: Add synthetic event error logging
Date
Add support for synthetic event error logging, which entails adding a
logging function for it, a way to save the synthetic event command,
and a set of specific synthetic event parse error strings and
handling.

[ <rostedt@goodmis.org>: wrote save_cmdstr() seq_buf implementation. ]
Signed-off-by: Tom Zanussi <zanussi@kernel.org>
---
kernel/trace/trace_events_synth.c | 92 ++++++++++++++++++++++++++++++-
1 file changed, 90 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c
index 8c9d6e464da0..7efe39be6576 100644
--- a/kernel/trace/trace_events_synth.c
+++ b/kernel/trace/trace_events_synth.c
@@ -20,6 +20,48 @@

#include "trace_synth.h"

+#undef ERRORS
+#define ERRORS \
+ C(BAD_NAME, "Illegal name"), \
+ C(CMD_INCOMPLETE, "Incomplete command"), \
+ C(EVENT_EXISTS, "Event already exists"), \
+ C(TOO_MANY_FIELDS, "Too many fields"), \
+ C(INCOMPLETE_TYPE, "Incomplete type"), \
+ C(INVALID_TYPE, "Invalid type"), \
+ C(INVALID_FIELD, "Invalid field"), \
+ C(CMD_TOO_LONG, "Command too long"),
+
+#undef C
+#define C(a, b) SYNTH_ERR_##a
+
+enum { ERRORS };
+
+#undef C
+#define C(a, b) b
+
+static const char *err_text[] = { ERRORS };
+
+static char last_cmd[MAX_FILTER_STR_VAL];
+
+static int errpos(const char *str)
+{
+ return err_pos(last_cmd, str);
+}
+
+static void last_cmd_set(char *str)
+{
+ if (!str)
+ return;
+
+ strncpy(last_cmd, str, MAX_FILTER_STR_VAL - 1);
+}
+
+static void synth_err(u8 err_type, u8 err_pos)
+{
+ tracing_log_err(NULL, "synthetic_events", last_cmd, err_text,
+ err_type, err_pos);
+}
+
static int create_synth_event(int argc, const char **argv);
static int synth_event_show(struct seq_file *m, struct dyn_event *ev);
static int synth_event_release(struct dyn_event *ev);
@@ -545,8 +587,10 @@ static struct synth_field *parse_synth_field(int argc, const char **argv,
field_type++;

if (!strcmp(field_type, "unsigned")) {
- if (argc < 3)
+ if (argc < 3) {
+ synth_err(SYNTH_ERR_INCOMPLETE_TYPE, errpos(field_type));
return ERR_PTR(-EINVAL);
+ }
prefix = "unsigned ";
field_type = argv[1];
field_name = argv[2];
@@ -573,6 +617,7 @@ static struct synth_field *parse_synth_field(int argc, const char **argv,
goto free;
}
if (!is_good_name(field->name)) {
+ synth_err(SYNTH_ERR_BAD_NAME, errpos(field_name));
ret = -EINVAL;
goto free;
}
@@ -601,6 +646,7 @@ static struct synth_field *parse_synth_field(int argc, const char **argv,

size = synth_field_size(field->type);
if (size < 0) {
+ synth_err(SYNTH_ERR_INVALID_TYPE, errpos(field_type));
ret = -EINVAL;
goto free;
} else if (size == 0) {
@@ -621,6 +667,7 @@ static struct synth_field *parse_synth_field(int argc, const char **argv,
field->is_dynamic = true;
size = sizeof(u64);
} else {
+ synth_err(SYNTH_ERR_INVALID_TYPE, errpos(field_type));
ret = -EINVAL;
goto free;
}
@@ -1098,12 +1145,47 @@ int synth_event_gen_cmd_array_start(struct dynevent_cmd *cmd, const char *name,
}
EXPORT_SYMBOL_GPL(synth_event_gen_cmd_array_start);

+static int save_cmdstr(int argc, const char *name, const char **argv)
+{
+ struct seq_buf s;
+ char *buf;
+ int i;
+
+ buf = kzalloc(MAX_DYNEVENT_CMD_LEN, GFP_KERNEL);
+ if (!buf)
+ return -ENOMEM;
+
+ seq_buf_init(&s, buf, MAX_DYNEVENT_CMD_LEN);
+
+ seq_buf_puts(&s, name);
+
+ for (i = 0; i < argc; i++) {
+ seq_buf_putc(&s, ' ');
+ seq_buf_puts(&s, argv[i]);
+ }
+
+ if (!seq_buf_buffer_left(&s)) {
+ synth_err(SYNTH_ERR_CMD_TOO_LONG, 0);
+ kfree(buf);
+ return -EINVAL;
+ }
+ buf[s.len] = 0;
+ last_cmd_set(buf);
+
+ kfree(buf);
+ return 0;
+}
+
static int __create_synth_event(int argc, const char *name, const char **argv)
{
struct synth_field *field, *fields[SYNTH_FIELDS_MAX];
struct synth_event *event = NULL;
int i, consumed = 0, n_fields = 0, ret = 0;

+ ret = save_cmdstr(argc, name, argv);
+ if (ret)
+ return ret;
+
/*
* Argument syntax:
* - Add synthetic event: <event_name> field[;field] ...
@@ -1111,18 +1193,22 @@ static int __create_synth_event(int argc, const char *name, const char **argv)
* where 'field' = type field_name
*/

- if (name[0] == '\0' || argc < 1)
+ if (name[0] == '\0' || argc < 1) {
+ synth_err(SYNTH_ERR_CMD_INCOMPLETE, 0);
return -EINVAL;
+ }

mutex_lock(&event_mutex);

if (!is_good_name(name)) {
+ synth_err(SYNTH_ERR_BAD_NAME, errpos(name));
ret = -EINVAL;
goto out;
}

event = find_synth_event(name);
if (event) {
+ synth_err(SYNTH_ERR_EVENT_EXISTS, errpos(name));
ret = -EEXIST;
goto out;
}
@@ -1131,6 +1217,7 @@ static int __create_synth_event(int argc, const char *name, const char **argv)
if (strcmp(argv[i], ";") == 0)
continue;
if (n_fields == SYNTH_FIELDS_MAX) {
+ synth_err(SYNTH_ERR_TOO_MANY_FIELDS, 0);
ret = -EINVAL;
goto err;
}
@@ -1145,6 +1232,7 @@ static int __create_synth_event(int argc, const char *name, const char **argv)
}

if (i < argc && strcmp(argv[i], ";") != 0) {
+ synth_err(SYNTH_ERR_INVALID_FIELD, errpos(argv[i]));
ret = -EINVAL;
goto err;
}
--
2.17.1
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