Date:   Mon, 7 Dec 2020 18:33:22 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Tom Zanussi <zanussi@...nel.org>
Cc:     axelrasmussen@...gle.com, mhiramat@...nel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/5] tracing/dynevent: Delegate parsing to create
 function


Hi Masami,

You had comments on this patch for v2. Is this one fine for you?

-- Steve


On Mon, 26 Oct 2020 10:06:09 -0500
Tom Zanussi <zanussi@...nel.org> wrote:

> From: Masami Hiramatsu <mhiramat@...nel.org>
> 
> Delegate command parsing to each create function so that the
> command syntax can be customized.
> 
> This requires changes to the kprobe/uprobe/synthetic event handling,
> which are also included here.
> 
> Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
> [ zanussi@...nel.org: added synthetic event modifications ]
> Signed-off-by: Tom Zanussi <zanussi@...nel.org>
> ---
>  kernel/trace/trace.c              | 23 ++----------
>  kernel/trace/trace.h              |  3 +-
>  kernel/trace/trace_dynevent.c     | 35 +++++++++++-------
>  kernel/trace/trace_dynevent.h     |  4 +--
>  kernel/trace/trace_events_synth.c | 60 +++++++++++++++++++++++--------
>  kernel/trace/trace_kprobe.c       | 33 +++++++++--------
>  kernel/trace/trace_probe.c        | 17 +++++++++
>  kernel/trace/trace_probe.h        |  1 +
>  kernel/trace/trace_uprobe.c       | 17 +++++----
>  9 files changed, 120 insertions(+), 73 deletions(-)
> 
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index 63c97012ed39..277d97220971 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -9367,30 +9367,11 @@ void ftrace_dump(enum ftrace_dump_mode oops_dump_mode)
>  }
>  EXPORT_SYMBOL_GPL(ftrace_dump);
>  
> -int trace_run_command(const char *buf, int (*createfn)(int, char **))
> -{
> -	char **argv;
> -	int argc, ret;
> -
> -	argc = 0;
> -	ret = 0;
> -	argv = argv_split(GFP_KERNEL, buf, &argc);
> -	if (!argv)
> -		return -ENOMEM;
> -
> -	if (argc)
> -		ret = createfn(argc, argv);
> -
> -	argv_free(argv);
> -
> -	return ret;
> -}
> -
>  #define WRITE_BUFSIZE  4096
>  
>  ssize_t trace_parse_run_command(struct file *file, const char __user *buffer,
>  				size_t count, loff_t *ppos,
> -				int (*createfn)(int, char **))
> +				int (*createfn)(const char *))
>  {
>  	char *kbuf, *buf, *tmp;
>  	int ret = 0;
> @@ -9438,7 +9419,7 @@ ssize_t trace_parse_run_command(struct file *file, const char __user *buffer,
>  			if (tmp)
>  				*tmp = '\0';
>  
> -			ret = trace_run_command(buf, createfn);
> +			ret = createfn(buf);
>  			if (ret)
>  				goto out;
>  			buf += size;
> diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
> index 34e0c4d5a6e7..02d7c487a30b 100644
> --- a/kernel/trace/trace.h
> +++ b/kernel/trace/trace.h
> @@ -1982,10 +1982,9 @@ extern int tracing_set_cpumask(struct trace_array *tr,
>  
>  #define MAX_EVENT_NAME_LEN	64
>  
> -extern int trace_run_command(const char *buf, int (*createfn)(int, char**));
>  extern ssize_t trace_parse_run_command(struct file *file,
>  		const char __user *buffer, size_t count, loff_t *ppos,
> -		int (*createfn)(int, char**));
> +		int (*createfn)(const char *));
>  
>  extern unsigned int err_pos(char *cmd, const char *str);
>  extern void tracing_log_err(struct trace_array *tr,
> diff --git a/kernel/trace/trace_dynevent.c b/kernel/trace/trace_dynevent.c
> index 5fa49cfd2bb6..af83bc5447fe 100644
> --- a/kernel/trace/trace_dynevent.c
> +++ b/kernel/trace/trace_dynevent.c
> @@ -31,23 +31,31 @@ int dyn_event_register(struct dyn_event_operations *ops)
>  	return 0;
>  }
>  
> -int dyn_event_release(int argc, char **argv, struct dyn_event_operations *type)
> +int dyn_event_release(const char *raw_command, struct dyn_event_operations *type)
>  {
>  	struct dyn_event *pos, *n;
>  	char *system = NULL, *event, *p;
> -	int ret = -ENOENT;
> +	int argc, ret = -ENOENT;
> +	char **argv;
> +
> +	argv = argv_split(GFP_KERNEL, raw_command, &argc);
> +	if (!argv)
> +		return -ENOMEM;
>  
>  	if (argv[0][0] == '-') {
> -		if (argv[0][1] != ':')
> -			return -EINVAL;
> +		if (argv[0][1] != ':') {
> +			ret = -EINVAL;
> +			goto out;
> +		}
>  		event = &argv[0][2];
>  	} else {
>  		event = strchr(argv[0], ':');
> -		if (!event)
> -			return -EINVAL;
> +		if (!event) {
> +			ret = -EINVAL;
> +			goto out;
> +		}
>  		event++;
>  	}
> -	argc--; argv++;
>  
>  	p = strchr(event, '/');
>  	if (p) {
> @@ -63,7 +71,7 @@ int dyn_event_release(int argc, char **argv, struct dyn_event_operations *type)
>  		if (type && type != pos->ops)
>  			continue;
>  		if (!pos->ops->match(system, event,
> -				argc, (const char **)argv, pos))
> +				argc - 1, (const char **)argv + 1, pos))
>  			continue;
>  
>  		ret = pos->ops->free(pos);
> @@ -71,21 +79,22 @@ int dyn_event_release(int argc, char **argv, struct dyn_event_operations *type)
>  			break;
>  	}
>  	mutex_unlock(&event_mutex);
> -
> +out:
> +	argv_free(argv);
>  	return ret;
>  }
>  
> -static int create_dyn_event(int argc, char **argv)
> +static int create_dyn_event(const char *raw_command)
>  {
>  	struct dyn_event_operations *ops;
>  	int ret = -ENODEV;
>  
> -	if (argv[0][0] == '-' || argv[0][0] == '!')
> -		return dyn_event_release(argc, argv, NULL);
> +	if (raw_command[0] == '-' || raw_command[0] == '!')
> +		return dyn_event_release(raw_command, NULL);
>  
>  	mutex_lock(&dyn_event_ops_mutex);
>  	list_for_each_entry(ops, &dyn_event_ops_list, list) {
> -		ret = ops->create(argc, (const char **)argv);
> +		ret = ops->create(raw_command);
>  		if (!ret || ret != -ECANCELED)
>  			break;
>  	}
> diff --git a/kernel/trace/trace_dynevent.h b/kernel/trace/trace_dynevent.h
> index d6857a254ede..4f4e03df4cbb 100644
> --- a/kernel/trace/trace_dynevent.h
> +++ b/kernel/trace/trace_dynevent.h
> @@ -39,7 +39,7 @@ struct dyn_event;
>   */
>  struct dyn_event_operations {
>  	struct list_head	list;
> -	int (*create)(int argc, const char *argv[]);
> +	int (*create)(const char *raw_command);
>  	int (*show)(struct seq_file *m, struct dyn_event *ev);
>  	bool (*is_busy)(struct dyn_event *ev);
>  	int (*free)(struct dyn_event *ev);
> @@ -97,7 +97,7 @@ void *dyn_event_seq_start(struct seq_file *m, loff_t *pos);
>  void *dyn_event_seq_next(struct seq_file *m, void *v, loff_t *pos);
>  void dyn_event_seq_stop(struct seq_file *m, void *v);
>  int dyn_events_release_all(struct dyn_event_operations *type);
> -int dyn_event_release(int argc, char **argv, struct dyn_event_operations *type);
> +int dyn_event_release(const char *raw_command, struct dyn_event_operations *type);
>  
>  /*
>   * for_each_dyn_event	-	iterate over the dyn_event list
> diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c
> index bdd427ccdfc5..271811fbf8fb 100644
> --- a/kernel/trace/trace_events_synth.c
> +++ b/kernel/trace/trace_events_synth.c
> @@ -62,7 +62,7 @@ static void synth_err(u8 err_type, u8 err_pos)
>  			err_type, err_pos);
>  }
>  
> -static int create_synth_event(int argc, const char **argv);
> +static int create_synth_event(const char *raw_command);
>  static int synth_event_show(struct seq_file *m, struct dyn_event *ev);
>  static int synth_event_release(struct dyn_event *ev);
>  static bool synth_event_is_busy(struct dyn_event *ev);
> @@ -1385,18 +1385,30 @@ int synth_event_delete(const char *event_name)
>  }
>  EXPORT_SYMBOL_GPL(synth_event_delete);
>  
> -static int create_or_delete_synth_event(int argc, char **argv)
> +static int create_or_delete_synth_event(const char *raw_command)
>  {
> -	const char *name = argv[0];
> -	int ret;
> +	char **argv, *name = NULL;
> +	int argc = 0, ret = 0;
> +
> +	argv = argv_split(GFP_KERNEL, raw_command, &argc);
> +	if (!argv)
> +		return -ENOMEM;
> +
> +	if (!argc)
> +		goto free;
> +
> +	name = argv[0];
>  
>  	/* trace_run_command() ensures argc != 0 */
>  	if (name[0] == '!') {
>  		ret = synth_event_delete(name + 1);
> -		return ret;
> +		goto free;
>  	}
>  
>  	ret = __create_synth_event(argc - 1, name, (const char **)argv + 1);
> +free:
> +	argv_free(argv);
> +
>  	return ret == -ECANCELED ? -EINVAL : ret;
>  }
>  
> @@ -1405,7 +1417,7 @@ static int synth_event_run_command(struct dynevent_cmd *cmd)
>  	struct synth_event *se;
>  	int ret;
>  
> -	ret = trace_run_command(cmd->seq.buffer, create_or_delete_synth_event);
> +	ret = create_or_delete_synth_event(cmd->seq.buffer);
>  	if (ret)
>  		return ret;
>  
> @@ -1941,23 +1953,43 @@ int synth_event_trace_end(struct synth_event_trace_state *trace_state)
>  }
>  EXPORT_SYMBOL_GPL(synth_event_trace_end);
>  
> -static int create_synth_event(int argc, const char **argv)
> +static int create_synth_event(const char *raw_command)
>  {
> -	const char *name = argv[0];
> -	int len;
> +	char **argv, *name;
> +	int len, argc = 0, ret = 0;
> +
> +	argv = argv_split(GFP_KERNEL, raw_command, &argc);
> +	if (!argv) {
> +		ret = -ENOMEM;
> +		return ret;
> +	}
>  
> -	if (name[0] != 's' || name[1] != ':')
> -		return -ECANCELED;
> +	if (!argc)
> +		goto free;
> +
> +	name = argv[0];
> +
> +	if (name[0] != 's' || name[1] != ':') {
> +		ret = -ECANCELED;
> +		goto free;
> +	}
>  	name += 2;
>  
>  	/* This interface accepts group name prefix */
>  	if (strchr(name, '/')) {
>  		len = str_has_prefix(name, SYNTH_SYSTEM "/");
> -		if (len == 0)
> -			return -EINVAL;
> +		if (len == 0) {
> +			ret = -EINVAL;
> +			goto free;
> +		}
>  		name += len;
>  	}
> -	return __create_synth_event(argc - 1, name, argv + 1);
> +
> +	ret = __create_synth_event(argc - 1, name, (const char **)argv + 1);
> +free:
> +	argv_free(argv);
> +
> +	return ret;
>  }
>  
>  static int synth_event_release(struct dyn_event *ev)
> diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
> index b911e9f6d9f5..ddef93e32905 100644
> --- a/kernel/trace/trace_kprobe.c
> +++ b/kernel/trace/trace_kprobe.c
> @@ -34,7 +34,7 @@ static int __init set_kprobe_boot_events(char *str)
>  }
>  __setup("kprobe_event=", set_kprobe_boot_events);
>  
> -static int trace_kprobe_create(int argc, const char **argv);
> +static int trace_kprobe_create(const char *raw_command);
>  static int trace_kprobe_show(struct seq_file *m, struct dyn_event *ev);
>  static int trace_kprobe_release(struct dyn_event *ev);
>  static bool trace_kprobe_is_busy(struct dyn_event *ev);
> @@ -710,7 +710,7 @@ static inline void sanitize_event_name(char *name)
>  			*name = '_';
>  }
>  
> -static int trace_kprobe_create(int argc, const char *argv[])
> +static int __trace_kprobe_create(int argc, const char *argv[])
>  {
>  	/*
>  	 * Argument syntax:
> @@ -907,20 +907,25 @@ static int trace_kprobe_create(int argc, const char *argv[])
>  	goto out;
>  }
>  
> -static int create_or_delete_trace_kprobe(int argc, char **argv)
> +static int trace_kprobe_create(const char *raw_command)
> +{
> +	return trace_probe_create(raw_command, __trace_kprobe_create);
> +}
> +
> +static int create_or_delete_trace_kprobe(const char *raw_command)
>  {
>  	int ret;
>  
> -	if (argv[0][0] == '-')
> -		return dyn_event_release(argc, argv, &trace_kprobe_ops);
> +	if (raw_command[0] == '-')
> +		return dyn_event_release(raw_command, &trace_kprobe_ops);
>  
> -	ret = trace_kprobe_create(argc, (const char **)argv);
> +	ret = trace_kprobe_create(raw_command);
>  	return ret == -ECANCELED ? -EINVAL : ret;
>  }
>  
>  static int trace_kprobe_run_command(struct dynevent_cmd *cmd)
>  {
> -	return trace_run_command(cmd->seq.buffer, create_or_delete_trace_kprobe);
> +	return create_or_delete_trace_kprobe(cmd->seq.buffer);
>  }
>  
>  /**
> @@ -1081,7 +1086,7 @@ int kprobe_event_delete(const char *name)
>  
>  	snprintf(buf, MAX_EVENT_NAME_LEN, "-:%s", name);
>  
> -	return trace_run_command(buf, create_or_delete_trace_kprobe);
> +	return create_or_delete_trace_kprobe(buf);
>  }
>  EXPORT_SYMBOL_GPL(kprobe_event_delete);
>  
> @@ -1884,7 +1889,7 @@ static __init void setup_boot_kprobe_events(void)
>  		if (p)
>  			*p++ = '\0';
>  
> -		ret = trace_run_command(cmd, create_or_delete_trace_kprobe);
> +		ret = create_or_delete_trace_kprobe(cmd);
>  		if (ret)
>  			pr_warn("Failed to add event(%d): %s\n", ret, cmd);
>  		else
> @@ -1982,8 +1987,7 @@ static __init int kprobe_trace_self_tests_init(void)
>  
>  	pr_info("Testing kprobe tracing: ");
>  
> -	ret = trace_run_command("p:testprobe kprobe_trace_selftest_target $stack $stack0 +0($stack)",
> -				create_or_delete_trace_kprobe);
> +	ret = create_or_delete_trace_kprobe("p:testprobe kprobe_trace_selftest_target $stack $stack0 +0($stack)");
>  	if (WARN_ON_ONCE(ret)) {
>  		pr_warn("error on probing function entry.\n");
>  		warn++;
> @@ -2004,8 +2008,7 @@ static __init int kprobe_trace_self_tests_init(void)
>  		}
>  	}
>  
> -	ret = trace_run_command("r:testprobe2 kprobe_trace_selftest_target $retval",
> -				create_or_delete_trace_kprobe);
> +	ret = create_or_delete_trace_kprobe("r:testprobe2 kprobe_trace_selftest_target $retval");
>  	if (WARN_ON_ONCE(ret)) {
>  		pr_warn("error on probing function return.\n");
>  		warn++;
> @@ -2078,13 +2081,13 @@ static __init int kprobe_trace_self_tests_init(void)
>  				trace_probe_event_call(&tk->tp), file);
>  	}
>  
> -	ret = trace_run_command("-:testprobe", create_or_delete_trace_kprobe);
> +	ret = create_or_delete_trace_kprobe("-:testprobe");
>  	if (WARN_ON_ONCE(ret)) {
>  		pr_warn("error on deleting a probe.\n");
>  		warn++;
>  	}
>  
> -	ret = trace_run_command("-:testprobe2", create_or_delete_trace_kprobe);
> +	ret = create_or_delete_trace_kprobe("-:testprobe2");
>  	if (WARN_ON_ONCE(ret)) {
>  		pr_warn("error on deleting a probe.\n");
>  		warn++;
> diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
> index d2867ccc6aca..ec589a4612df 100644
> --- a/kernel/trace/trace_probe.c
> +++ b/kernel/trace/trace_probe.c
> @@ -1134,3 +1134,20 @@ bool trace_probe_match_command_args(struct trace_probe *tp,
>  	}
>  	return true;
>  }
> +
> +int trace_probe_create(const char *raw_command, int (*createfn)(int, const char **))
> +{
> +	int argc = 0, ret = 0;
> +	char **argv;
> +
> +	argv = argv_split(GFP_KERNEL, raw_command, &argc);
> +	if (!argv)
> +		return -ENOMEM;
> +
> +	if (argc)
> +		ret = createfn(argc, (const char **)argv);
> +
> +	argv_free(argv);
> +
> +	return ret;
> +}
> diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
> index 2f703a20c724..7ce4027089ee 100644
> --- a/kernel/trace/trace_probe.h
> +++ b/kernel/trace/trace_probe.h
> @@ -341,6 +341,7 @@ struct event_file_link *trace_probe_get_file_link(struct trace_probe *tp,
>  int trace_probe_compare_arg_type(struct trace_probe *a, struct trace_probe *b);
>  bool trace_probe_match_command_args(struct trace_probe *tp,
>  				    int argc, const char **argv);
> +int trace_probe_create(const char *raw_command, int (*createfn)(int, const char **));
>  
>  #define trace_probe_for_each_link(pos, tp)	\
>  	list_for_each_entry(pos, &(tp)->event->files, list)
> diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
> index 3cf7128e1ad3..e6b56a65f80f 100644
> --- a/kernel/trace/trace_uprobe.c
> +++ b/kernel/trace/trace_uprobe.c
> @@ -34,7 +34,7 @@ struct uprobe_trace_entry_head {
>  #define DATAOF_TRACE_ENTRY(entry, is_return)		\
>  	((void*)(entry) + SIZEOF_TRACE_ENTRY(is_return))
>  
> -static int trace_uprobe_create(int argc, const char **argv);
> +static int trace_uprobe_create(const char *raw_command);
>  static int trace_uprobe_show(struct seq_file *m, struct dyn_event *ev);
>  static int trace_uprobe_release(struct dyn_event *ev);
>  static bool trace_uprobe_is_busy(struct dyn_event *ev);
> @@ -530,7 +530,7 @@ static int register_trace_uprobe(struct trace_uprobe *tu)
>   * Argument syntax:
>   *  - Add uprobe: p|r[:[GRP/]EVENT] PATH:OFFSET[%return][(REF)] [FETCHARGS]
>   */
> -static int trace_uprobe_create(int argc, const char **argv)
> +static int __trace_uprobe_create(int argc, const char **argv)
>  {
>  	struct trace_uprobe *tu;
>  	const char *event = NULL, *group = UPROBE_EVENT_SYSTEM;
> @@ -716,14 +716,19 @@ static int trace_uprobe_create(int argc, const char **argv)
>  	return ret;
>  }
>  
> -static int create_or_delete_trace_uprobe(int argc, char **argv)
> +int trace_uprobe_create(const char *raw_command)
> +{
> +	return trace_probe_create(raw_command, __trace_uprobe_create);
> +}
> +
> +static int create_or_delete_trace_uprobe(const char *raw_command)
>  {
>  	int ret;
>  
> -	if (argv[0][0] == '-')
> -		return dyn_event_release(argc, argv, &trace_uprobe_ops);
> +	if (raw_command[0] == '-')
> +		return dyn_event_release(raw_command, &trace_uprobe_ops);
>  
> -	ret = trace_uprobe_create(argc, (const char **)argv);
> +	ret = trace_uprobe_create(raw_command);
>  	return ret == -ECANCELED ? -EINVAL : ret;
>  }
>  

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