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Date: Fri, 22 Jan 2021 22:16:09 +0900
From: Masami Hiramatsu <mhiramat@...nel.org>
To: Tom Zanussi <zanussi@...nel.org>
Cc: rostedt@...dmis.org, axelrasmussen@...gle.com, mhiramat@...nel.org,
dan.carpenter@...cle.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 2/6] tracing: Rework synthetic event command parsing
On Thu, 21 Jan 2021 11:01:05 -0600
Tom Zanussi <zanussi@...nel.org> wrote:
> Now that command parsing has been delegated to the create functions
> and we're no longer constrained by argv_split(), we can modify the
> synthetic event command parser to better match the higher-level
> structure of the synthetic event commands, which is basically an event
> name followed by a set of semicolon-separated fields.
>
> Since we're also now passed the raw command, we can also save it
> directly and can get rid of save_cmdstr().
>
This looks good to me.
Reviewed-by: Masami Hiramatsu <mhiramat@...nel.org>
Thank you,
> Signed-off-by: Tom Zanussi <zanussi@...nel.org>
> ---
> kernel/trace/trace_events_synth.c | 198 +++++++++++++++---------------
> 1 file changed, 98 insertions(+), 100 deletions(-)
>
> diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c
> index b2588a5650c9..a79c17b97add 100644
> --- a/kernel/trace/trace_events_synth.c
> +++ b/kernel/trace/trace_events_synth.c
> @@ -48,7 +48,7 @@ static int errpos(const char *str)
> return err_pos(last_cmd, str);
> }
>
> -static void last_cmd_set(char *str)
> +static void last_cmd_set(const char *str)
> {
> if (!str)
> return;
> @@ -579,18 +579,14 @@ static void free_synth_field(struct synth_field *field)
> kfree(field);
> }
>
> -static struct synth_field *parse_synth_field(int argc, const char **argv,
> - int *consumed)
> +static struct synth_field *parse_synth_field(int argc, char **argv)
> {
> - struct synth_field *field;
> const char *prefix = NULL, *field_type = argv[0], *field_name, *array;
> - int len, ret = -ENOMEM;
> + int len, consumed, ret = -ENOMEM;
> + struct synth_field *field;
> struct seq_buf s;
> ssize_t size;
>
> - if (field_type[0] == ';')
> - field_type++;
> -
> if (!strcmp(field_type, "unsigned")) {
> if (argc < 3) {
> synth_err(SYNTH_ERR_INCOMPLETE_TYPE, errpos(field_type));
> @@ -599,10 +595,20 @@ static struct synth_field *parse_synth_field(int argc, const char **argv,
> prefix = "unsigned ";
> field_type = argv[1];
> field_name = argv[2];
> - *consumed = 3;
> + consumed = 3;
> } else {
> field_name = argv[1];
> - *consumed = 2;
> + consumed = 2;
> + }
> +
> + if (consumed < argc) {
> + synth_err(SYNTH_ERR_INVALID_FIELD, errpos(field_type));
> + return ERR_PTR(-EINVAL);
> + }
> +
> + if (!field_name) {
> + synth_err(SYNTH_ERR_INVALID_FIELD, errpos(field_type));
> + return ERR_PTR(-EINVAL);
> }
>
> field = kzalloc(sizeof(*field), GFP_KERNEL);
> @@ -613,8 +619,6 @@ static struct synth_field *parse_synth_field(int argc, const char **argv,
> array = strchr(field_name, '[');
> if (array)
> len -= strlen(array);
> - else if (field_name[len - 1] == ';')
> - len--;
>
> field->name = kmemdup_nul(field_name, len, GFP_KERNEL);
> if (!field->name)
> @@ -626,8 +630,6 @@ static struct synth_field *parse_synth_field(int argc, const char **argv,
> goto free;
> }
>
> - if (field_type[0] == ';')
> - field_type++;
> len = strlen(field_type) + 1;
>
> if (array)
> @@ -644,11 +646,8 @@ static struct synth_field *parse_synth_field(int argc, const char **argv,
> if (prefix)
> seq_buf_puts(&s, prefix);
> seq_buf_puts(&s, field_type);
> - if (array) {
> + if (array)
> seq_buf_puts(&s, array);
> - if (s.buffer[s.len - 1] == ';')
> - s.len--;
> - }
> if (WARN_ON_ONCE(!seq_buf_buffer_left(&s)))
> goto free;
>
> @@ -1160,46 +1159,12 @@ 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)
> +static int __create_synth_event(const char *name, const char *raw_fields)
> {
> + char **argv, *field_str, *tmp_fields, *saved_fields = NULL;
> struct synth_field *field, *fields[SYNTH_FIELDS_MAX];
> + int i, argc, n_fields = 0, ret = 0;
> 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:
> @@ -1208,13 +1173,14 @@ static int __create_synth_event(int argc, const char *name, const char **argv)
> * where 'field' = type field_name
> */
>
> - if (name[0] == '\0' || argc < 1) {
> + mutex_lock(&event_mutex);
> +
> + if (name[0] == '\0') {
> synth_err(SYNTH_ERR_CMD_INCOMPLETE, 0);
> - return -EINVAL;
> + ret = -EINVAL;
> + goto out;
> }
>
> - mutex_lock(&event_mutex);
> -
> if (!is_good_name(name)) {
> synth_err(SYNTH_ERR_BAD_NAME, errpos(name));
> ret = -EINVAL;
> @@ -1228,26 +1194,41 @@ static int __create_synth_event(int argc, const char *name, const char **argv)
> goto out;
> }
>
> - for (i = 0; i < argc - 1; i++) {
> - if (strcmp(argv[i], ";") == 0)
> - continue;
> - if (n_fields == SYNTH_FIELDS_MAX) {
> - synth_err(SYNTH_ERR_TOO_MANY_FIELDS, 0);
> - ret = -EINVAL;
> + tmp_fields = saved_fields = kstrdup(raw_fields, GFP_KERNEL);
> + if (!tmp_fields) {
> + ret = -ENOMEM;
> + goto out;
> + }
> +
> + while ((field_str = strsep(&tmp_fields, ";")) != NULL) {
> + argv = argv_split(GFP_KERNEL, field_str, &argc);
> + if (!argv) {
> + ret = -ENOMEM;
> goto err;
> }
>
> - field = parse_synth_field(argc - i, &argv[i], &consumed);
> + if (!argc)
> + continue;
> +
> + field = parse_synth_field(argc, argv);
> if (IS_ERR(field)) {
> + argv_free(argv);
> ret = PTR_ERR(field);
> goto err;
> }
> +
> + argv_free(argv);
> +
> fields[n_fields++] = field;
> - i += consumed - 1;
> + if (n_fields == SYNTH_FIELDS_MAX) {
> + synth_err(SYNTH_ERR_TOO_MANY_FIELDS, 0);
> + ret = -EINVAL;
> + goto err;
> + }
> }
>
> - if (i < argc && strcmp(argv[i], ";") != 0) {
> - synth_err(SYNTH_ERR_INVALID_FIELD, errpos(argv[i]));
> + if (n_fields == 0) {
> + synth_err(SYNTH_ERR_CMD_INCOMPLETE, 0);
> ret = -EINVAL;
> goto err;
> }
> @@ -1266,6 +1247,8 @@ static int __create_synth_event(int argc, const char *name, const char **argv)
> out:
> mutex_unlock(&event_mutex);
>
> + kfree(saved_fields);
> +
> return ret;
> err:
> for (i = 0; i < n_fields; i++)
> @@ -1385,29 +1368,38 @@ EXPORT_SYMBOL_GPL(synth_event_delete);
>
> static int create_or_delete_synth_event(const char *raw_command)
> {
> - char **argv, *name = NULL;
> - int argc = 0, ret = 0;
> + char *name = NULL, *fields, *p;
> + int ret = 0;
>
> - argv = argv_split(GFP_KERNEL, raw_command, &argc);
> - if (!argv)
> - return -ENOMEM;
> + raw_command = skip_spaces(raw_command);
> + if (raw_command[0] == '\0')
> + return ret;
> +
> + last_cmd_set(raw_command);
>
> - if (!argc)
> + p = strpbrk(raw_command, " \t");
> + if (!p && raw_command[0] != '!') {
> + synth_err(SYNTH_ERR_CMD_INCOMPLETE, 0);
> + ret = -EINVAL;
> goto free;
> + }
>
> - name = argv[0];
> + name = kmemdup_nul(raw_command, p ? p - raw_command : strlen(raw_command), GFP_KERNEL);
> + if (!name)
> + return -ENOMEM;
>
> - /* trace_run_command() ensures argc != 0 */
> if (name[0] == '!') {
> ret = synth_event_delete(name + 1);
> goto free;
> }
>
> - ret = __create_synth_event(argc - 1, name, (const char **)argv + 1);
> + fields = skip_spaces(p);
> +
> + ret = __create_synth_event(name, fields);
> free:
> - argv_free(argv);
> + kfree(name);
>
> - return ret == -ECANCELED ? -EINVAL : ret;
> + return ret;
> }
>
> static int synth_event_run_command(struct dynevent_cmd *cmd)
> @@ -1953,39 +1945,45 @@ EXPORT_SYMBOL_GPL(synth_event_trace_end);
>
> static int create_synth_event(const char *raw_command)
> {
> - char **argv, *name;
> - int len, argc = 0, ret = 0;
> + char *fields, *p;
> + const char *name;
> + int len, ret = 0;
>
> - argv = argv_split(GFP_KERNEL, raw_command, &argc);
> - if (!argv) {
> - ret = -ENOMEM;
> + raw_command = skip_spaces(raw_command);
> + if (raw_command[0] == '\0')
> return ret;
> - }
>
> - if (!argc)
> - goto free;
> + last_cmd_set(raw_command);
>
> - name = argv[0];
> + p = strpbrk(raw_command, " \t");
> + if (!p)
> + return -EINVAL;
>
> - if (name[0] != 's' || name[1] != ':') {
> - ret = -ECANCELED;
> - goto free;
> - }
> + fields = skip_spaces(p);
> +
> + name = raw_command;
> +
> + if (name[0] != 's' || name[1] != ':')
> + return -ECANCELED;
> name += 2;
>
> /* This interface accepts group name prefix */
> if (strchr(name, '/')) {
> len = str_has_prefix(name, SYNTH_SYSTEM "/");
> - if (len == 0) {
> - ret = -EINVAL;
> - goto free;
> - }
> + if (len == 0)
> + return -EINVAL;
> name += len;
> }
>
> - ret = __create_synth_event(argc - 1, name, (const char **)argv + 1);
> -free:
> - argv_free(argv);
> + len = name - raw_command;
> +
> + name = kmemdup_nul(raw_command + len, p - raw_command - len, GFP_KERNEL);
> + if (!name)
> + return -ENOMEM;
> +
> + ret = __create_synth_event(name, fields);
> +
> + kfree(name);
>
> return ret;
> }
> --
> 2.17.1
>
--
Masami Hiramatsu <mhiramat@...nel.org>
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