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Date: Sat, 10 Oct 2020 23:57:54 +0900
From: Masami Hiramatsu <mhiramat@...nel.org>
To: Tom Zanussi <zanussi@...nel.org>
Cc: rostedt@...dmis.org, axelrasmussen@...gle.com, mhiramat@...nel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/5] tracing: Add synthetic event error logging
On Fri, 9 Oct 2020 10:17:10 -0500
Tom Zanussi <zanussi@...nel.org> wrote:
> 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.
Thanks for fixing this. But it seems that the INVALID_TYPE error
position is not correct.
/sys/kernel/debug/tracing # echo "myevent chr arg" >> synthetic_events
sh: write error: Invalid argument
/sys/kernel/debug/tracing # cat error_log
[ 1354.611660] synthetic_events: error: Invalid type
Command: myevent chr arg
^
If the type is invalid, it should point "chr" instead of "arg".
If you add a syntax error testcase as same as kprobe_events, you can
check the error position too.
Thank you,
>
> Signed-off-by: Tom Zanussi <zanussi@...nel.org>
> ---
> kernel/trace/trace_events_synth.c | 114 +++++++++++++++++++++++++++++-
> 1 file changed, 112 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c
> index 8c9d6e464da0..ce4cae5cfd47 100644
> --- a/kernel/trace/trace_events_synth.c
> +++ b/kernel/trace/trace_events_synth.c
> @@ -20,6 +20,53 @@
>
> #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;
> +
> + strncat(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 void synth_err_clear(void)
> +{
> + last_cmd[0] = '\0';
> +}
> +
> 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 +592,10 @@ 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 +622,7 @@ 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 +651,7 @@ 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->name));
> ret = -EINVAL;
> goto free;
> } else if (size == 0) {
> @@ -621,6 +672,7 @@ 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->name));
> ret = -EINVAL;
> goto free;
> }
> @@ -1098,12 +1150,64 @@ 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 cmdstr_append(char *buf, const char *str, int *remaining)
> +{
> + int len = strlen(str);
> +
> + if (len + 1 >= *remaining) {
> + synth_err(SYNTH_ERR_CMD_TOO_LONG, 0);
> + return -EINVAL;
> + }
> +
> + strcat(buf, str);
> + strcat(buf, " ");
> + *remaining -= len + 1;
> +
> + return 0;
> +}
> +
> +static int save_cmdstr(int argc, const char *name, const char **argv)
> +{
> + int i, ret, remaining = MAX_DYNEVENT_CMD_LEN;
> + char *buf;
> +
> + synth_err_clear();
> +
> + buf = kzalloc(MAX_DYNEVENT_CMD_LEN, GFP_KERNEL);
> + if (!buf)
> + return -ENOMEM;
> +
> + ret = cmdstr_append(buf, name, &remaining);
> + if (ret) {
> + kfree(buf);
> + return ret;
> + }
> +
> + for (i = 0; i < argc; i++) {
> + ret = cmdstr_append(buf, argv[i], &remaining);
> + if (ret) {
> + kfree(buf);
> + return ret;
> + }
> + }
> +
> + last_cmd_set(buf);
> +
> + kfree(buf);
> +
> + return ret;
> +}
> +
> 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 +1215,22 @@ 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 +1239,7 @@ 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 +1254,7 @@ 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
>
--
Masami Hiramatsu <mhiramat@...nel.org>
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