[PATCH 0/4] tracing: Updates to dynamic event API

[PATCH 0/4] tracing: Updates to dynamic event API

[Tom Zanussi]

Hi Steve,

This patchset adds some updates to the 'tracing: Add support for
in-kernel dynamic event API', on top of ftrace/core, addressing the
comments from v4 of that:

  - Consolidate the very similar functions
    synth_event_add_val/next_val() and inline find_synth_field(), as
    suggested by Steve

  - Replace the command-building code in dynevent_cmd with equivalent
    seq_buf functionality, as suggested by Steve

  - Move the check_arg callbacks from the arg objects and explicitly
    pass them to the add functions, as suggested by Masami

  - Get rid of a useless bit of code in dynevent_add_arg_pair() as
    suggested by Masami

With these changes the dynamic event test modules work fine and the
trigger selftests all pass.

Thanks,

Tom


The following changes since commit d380dcde9a07ca5de4805dee11f58a98ec0ad6ff:

  tracing: Fix now invalid var_ref_vals assumption in trace action (2020-01-31 12:59:26 -0500)

are available in the git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/zanussi/linux-trace.git ftrace/synth-event-gen-updates-v1

Tom Zanussi (4):
  tracing: Consolidate some synth_event_trace code
  tracing: Remove check_arg() callbacks from dynevent args
  tracing: Remove useless code in dynevent_arg_pair_add()
  tracing: Use seq_buf for building dynevent_cmd string

 include/linux/trace_events.h     |   4 +-
 kernel/trace/trace_dynevent.c    | 110 ++++++++++-----------------
 kernel/trace/trace_dynevent.h    |  11 ++-
 kernel/trace/trace_events_hist.c | 157 ++++++++++++++++-----------------------
 kernel/trace/trace_kprobe.c      |  12 +--
 5 files changed, 118 insertions(+), 176 deletions(-)

-- 
2.14.1

[PATCH 1/4] tracing: Consolidate some synth_event_trace code

[Tom Zanussi]

The synth_event trace code contains some almost identical functions
and some small functions that are called only once - consolidate the
common code into single functions and fold in the small functions to
simplify the code overall.

Signed-off-by: Tom Zanussi <zanussi@kernel.org>
---
 kernel/trace/trace_events_hist.c | 139 ++++++++++++++++-----------------------
 1 file changed, 56 insertions(+), 83 deletions(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 5b4e04780411..772bd3d7c29f 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -2053,24 +2053,72 @@ int synth_event_trace_start(struct trace_event_file *file,
 }
 EXPORT_SYMBOL_GPL(synth_event_trace_start);
 
-static int save_synth_val(struct synth_field *field, u64 val,
+int __synth_event_add_val(const char *field_name, u64 val,
 			  struct synth_event_trace_state *trace_state)
 {
-	struct synth_trace_event *entry = trace_state->entry;
+	struct synth_field *field = NULL;
+	struct synth_trace_event *entry;
+	struct synth_event *event;
+	int i, ret = 0;
+
+	if (!trace_state) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	/* can't mix add_next_synth_val() with add_synth_val() */
+	if (field_name) {
+		if (trace_state->add_next) {
+			ret = -EINVAL;
+			goto out;
+		}
+		trace_state->add_name = true;
+	} else {
+		if (trace_state->add_name) {
+			ret = -EINVAL;
+			goto out;
+		}
+		trace_state->add_next = true;
+	}
+
+	if (!trace_state->enabled)
+		goto out;
+
+	event = trace_state->event;
+	if (trace_state->add_name) {
+		for (i = 0; i < event->n_fields; i++) {
+			field = event->fields[i];
+			if (strcmp(field->name, field_name) == 0)
+				break;
+		}
+		if (!field) {
+			ret = -EINVAL;
+			goto out;
+		}
+	} else {
+		if (trace_state->cur_field >= event->n_fields) {
+			ret = -EINVAL;
+			goto out;
+		}
+		field = event->fields[trace_state->cur_field++];
+	}
 
+	entry = trace_state->entry;
 	if (field->is_string) {
 		char *str_val = (char *)(long)val;
 		char *str_field;
 
-		if (!str_val)
-			return -EINVAL;
+		if (!str_val) {
+			ret = -EINVAL;
+			goto out;
+		}
 
 		str_field = (char *)&entry->fields[field->offset];
 		strscpy(str_field, str_val, STR_VAR_LEN_MAX);
 	} else
 		entry->fields[field->offset] = val;
-
-	return 0;
+ out:
+	return ret;
 }
 
 /**
@@ -2104,54 +2152,10 @@ static int save_synth_val(struct synth_field *field, u64 val,
 int synth_event_add_next_val(u64 val,
 			     struct synth_event_trace_state *trace_state)
 {
-	struct synth_field *field;
-	struct synth_event *event;
-	int ret = 0;
-
-	if (!trace_state) {
-		ret = -EINVAL;
-		goto out;
-	}
-
-	/* can't mix add_next_synth_val() with add_synth_val() */
-	if (trace_state->add_name) {
-		ret = -EINVAL;
-		goto out;
-	}
-	trace_state->add_next = true;
-
-	if (!trace_state->enabled)
-		goto out;
-
-	event = trace_state->event;
-
-	if (trace_state->cur_field >= event->n_fields) {
-		ret = -EINVAL;
-		goto out;
-	}
-
-	field = event->fields[trace_state->cur_field++];
-	ret = save_synth_val(field, val, trace_state);
- out:
-	return ret;
+	return __synth_event_add_val(NULL, val, trace_state);
 }
 EXPORT_SYMBOL_GPL(synth_event_add_next_val);
 
-static struct synth_field *find_synth_field(struct synth_event *event,
-					    const char *field_name)
-{
-	struct synth_field *field = NULL;
-	unsigned int i;
-
-	for (i = 0; i < event->n_fields; i++) {
-		field = event->fields[i];
-		if (strcmp(field->name, field_name) == 0)
-			return field;
-	}
-
-	return NULL;
-}
-
 /**
  * synth_event_add_val - Add a named field's value to an open synth trace
  * @field_name: The name of the synthetic event field value to set
@@ -2183,38 +2187,7 @@ static struct synth_field *find_synth_field(struct synth_event *event,
 int synth_event_add_val(const char *field_name, u64 val,
 			struct synth_event_trace_state *trace_state)
 {
-	struct synth_trace_event *entry;
-	struct synth_event *event;
-	struct synth_field *field;
-	int ret = 0;
-
-	if (!trace_state) {
-		ret = -EINVAL;
-		goto out;
-	}
-
-	/* can't mix add_next_synth_val() with add_synth_val() */
-	if (trace_state->add_next) {
-		ret = -EINVAL;
-		goto out;
-	}
-	trace_state->add_name = true;
-
-	if (!trace_state->enabled)
-		goto out;
-
-	event = trace_state->event;
-	entry = trace_state->entry;
-
-	field = find_synth_field(event, field_name);
-	if (!field) {
-		ret = -EINVAL;
-		goto out;
-	}
-
-	ret = save_synth_val(field, val, trace_state);
- out:
-	return ret;
+	return __synth_event_add_val(field_name, val, trace_state);
 }
 EXPORT_SYMBOL_GPL(synth_event_add_val);
 
-- 
2.14.1

Re: [PATCH 1/4] tracing: Consolidate some synth_event_trace code

[Steven Rostedt]

On Fri, 31 Jan 2020 15:55:31 -0600
Tom Zanussi <zanussi@kernel.org> wrote:

> +++ b/kernel/trace/trace_events_hist.c
> @@ -2053,24 +2053,72 @@ int synth_event_trace_start(struct trace_event_file *file,
>  }
>  EXPORT_SYMBOL_GPL(synth_event_trace_start);
>  
> -static int save_synth_val(struct synth_field *field, u64 val,
> +int __synth_event_add_val(const char *field_name, u64 val,

Hmm, shouldn't __synth_event_add_val() still be static?

-- Steve

>  			  struct synth_event_trace_state *trace_state)
>  {
> -	struct synth_trace_event *entry = trace_state->entry;
> +	struct synth_field *field = NULL;
> +	struct synth_trace_event *entry;
> +	struct synth_event *event;
> +	int i, ret = 0;
> +

Re: [PATCH 1/4] tracing: Consolidate some synth_event_trace code

[Tom Zanussi]

Hi Steve,

On Fri, 2020-01-31 at 17:43 -0500, Steven Rostedt wrote:
> On Fri, 31 Jan 2020 15:55:31 -0600
> Tom Zanussi <zanussi@kernel.org> wrote:
> 
> > +++ b/kernel/trace/trace_events_hist.c
> > @@ -2053,24 +2053,72 @@ int synth_event_trace_start(struct
> > trace_event_file *file,
> >  }
> >  EXPORT_SYMBOL_GPL(synth_event_trace_start);
> >  
> > -static int save_synth_val(struct synth_field *field, u64 val,
> > +int __synth_event_add_val(const char *field_name, u64 val,
> 
> Hmm, shouldn't __synth_event_add_val() still be static?
> 

It's a new function, but yeah, it should be static.

Tom

> -- Steve
> 
> >  			  struct synth_event_trace_state
> > *trace_state)
> >  {
> > -	struct synth_trace_event *entry = trace_state->entry;
> > +	struct synth_field *field = NULL;
> > +	struct synth_trace_event *entry;
> > +	struct synth_event *event;
> > +	int i, ret = 0;
> > +

Re: [PATCH 1/4] tracing: Consolidate some synth_event_trace code

[Tom Zanussi]

On Fri, 2020-01-31 at 17:43 -0500, Steven Rostedt wrote:
> On Fri, 31 Jan 2020 15:55:31 -0600
> Tom Zanussi <zanussi@kernel.org> wrote:
> 
> > +++ b/kernel/trace/trace_events_hist.c
> > @@ -2053,24 +2053,72 @@ int synth_event_trace_start(struct
> > trace_event_file *file,
> >  }
> >  EXPORT_SYMBOL_GPL(synth_event_trace_start);
> >  
> > -static int save_synth_val(struct synth_field *field, u64 val,
> > +int __synth_event_add_val(const char *field_name, u64 val,
> 
> Hmm, shouldn't __synth_event_add_val() still be static?
> 
> -- Steve
> 
> >  			  struct synth_event_trace_state
> > *trace_state)
> >  {
> > -	struct synth_trace_event *entry = trace_state->entry;
> > +	struct synth_field *field = NULL;
> > +	struct synth_trace_event *entry;
> > +	struct synth_event *event;
> > +	int i, ret = 0;
> > +

Here's the patch with __synth_event_add_val() made static.  Let me know
if you want me to just do a v2 of this series..

Thanks,

Tom

[PATCH] tracing: Consolidate some synth_event_trace code

The synth_event trace code contains some almost identical functions
and some small functions that are called only once - consolidate the
common code into single functions and fold in the small functions to
simplify the code overall.

Signed-off-by: Tom Zanussi <zanussi@kernel.org>
---
 kernel/trace/trace_events_hist.c | 141 ++++++++++++++++-----------------------
 1 file changed, 57 insertions(+), 84 deletions(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 5b4e04780411..42058a1b5146 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -2053,24 +2053,72 @@ int synth_event_trace_start(struct trace_event_file *file,
 }
 EXPORT_SYMBOL_GPL(synth_event_trace_start);
 
-static int save_synth_val(struct synth_field *field, u64 val,
-			  struct synth_event_trace_state *trace_state)
+static int __synth_event_add_val(const char *field_name, u64 val,
+				 struct synth_event_trace_state *trace_state)
 {
-	struct synth_trace_event *entry = trace_state->entry;
+	struct synth_field *field = NULL;
+	struct synth_trace_event *entry;
+	struct synth_event *event;
+	int i, ret = 0;
+
+	if (!trace_state) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	/* can't mix add_next_synth_val() with add_synth_val() */
+	if (field_name) {
+		if (trace_state->add_next) {
+			ret = -EINVAL;
+			goto out;
+		}
+		trace_state->add_name = true;
+	} else {
+		if (trace_state->add_name) {
+			ret = -EINVAL;
+			goto out;
+		}
+		trace_state->add_next = true;
+	}
+
+	if (!trace_state->enabled)
+		goto out;
+
+	event = trace_state->event;
+	if (trace_state->add_name) {
+		for (i = 0; i < event->n_fields; i++) {
+			field = event->fields[i];
+			if (strcmp(field->name, field_name) == 0)
+				break;
+		}
+		if (!field) {
+			ret = -EINVAL;
+			goto out;
+		}
+	} else {
+		if (trace_state->cur_field >= event->n_fields) {
+			ret = -EINVAL;
+			goto out;
+		}
+		field = event->fields[trace_state->cur_field++];
+	}
 
+	entry = trace_state->entry;
 	if (field->is_string) {
 		char *str_val = (char *)(long)val;
 		char *str_field;
 
-		if (!str_val)
-			return -EINVAL;
+		if (!str_val) {
+			ret = -EINVAL;
+			goto out;
+		}
 
 		str_field = (char *)&entry->fields[field->offset];
 		strscpy(str_field, str_val, STR_VAR_LEN_MAX);
 	} else
 		entry->fields[field->offset] = val;
-
-	return 0;
+ out:
+	return ret;
 }
 
 /**
@@ -2104,54 +2152,10 @@ static int save_synth_val(struct synth_field *field, u64 val,
 int synth_event_add_next_val(u64 val,
 			     struct synth_event_trace_state *trace_state)
 {
-	struct synth_field *field;
-	struct synth_event *event;
-	int ret = 0;
-
-	if (!trace_state) {
-		ret = -EINVAL;
-		goto out;
-	}
-
-	/* can't mix add_next_synth_val() with add_synth_val() */
-	if (trace_state->add_name) {
-		ret = -EINVAL;
-		goto out;
-	}
-	trace_state->add_next = true;
-
-	if (!trace_state->enabled)
-		goto out;
-
-	event = trace_state->event;
-
-	if (trace_state->cur_field >= event->n_fields) {
-		ret = -EINVAL;
-		goto out;
-	}
-
-	field = event->fields[trace_state->cur_field++];
-	ret = save_synth_val(field, val, trace_state);
- out:
-	return ret;
+	return __synth_event_add_val(NULL, val, trace_state);
 }
 EXPORT_SYMBOL_GPL(synth_event_add_next_val);
 
-static struct synth_field *find_synth_field(struct synth_event *event,
-					    const char *field_name)
-{
-	struct synth_field *field = NULL;
-	unsigned int i;
-
-	for (i = 0; i < event->n_fields; i++) {
-		field = event->fields[i];
-		if (strcmp(field->name, field_name) == 0)
-			return field;
-	}
-
-	return NULL;
-}
-
 /**
  * synth_event_add_val - Add a named field's value to an open synth trace
  * @field_name: The name of the synthetic event field value to set
@@ -2183,38 +2187,7 @@ static struct synth_field *find_synth_field(struct synth_event *event,
 int synth_event_add_val(const char *field_name, u64 val,
 			struct synth_event_trace_state *trace_state)
 {
-	struct synth_trace_event *entry;
-	struct synth_event *event;
-	struct synth_field *field;
-	int ret = 0;
-
-	if (!trace_state) {
-		ret = -EINVAL;
-		goto out;
-	}
-
-	/* can't mix add_next_synth_val() with add_synth_val() */
-	if (trace_state->add_next) {
-		ret = -EINVAL;
-		goto out;
-	}
-	trace_state->add_name = true;
-
-	if (!trace_state->enabled)
-		goto out;
-
-	event = trace_state->event;
-	entry = trace_state->entry;
-
-	field = find_synth_field(event, field_name);
-	if (!field) {
-		ret = -EINVAL;
-		goto out;
-	}
-
-	ret = save_synth_val(field, val, trace_state);
- out:
-	return ret;
+	return __synth_event_add_val(field_name, val, trace_state);
 }
 EXPORT_SYMBOL_GPL(synth_event_add_val);
 
-- 
2.14.1

Re: [PATCH 1/4] tracing: Consolidate some synth_event_trace code

[Steven Rostedt]

On Fri, 31 Jan 2020 17:00:32 -0600
Tom Zanussi <zanussi@kernel.org> wrote:
> 
> Here's the patch with __synth_event_add_val() made static.  Let me know
> if you want me to just do a v2 of this series..
> 

No, I'll just pull this in over the other one and start testing it.

Thanks a lot for getting this done today!

-- Steve

[PATCH 2/4] tracing: Remove check_arg() callbacks from dynevent args

[Tom Zanussi]

It's kind of strange to have check_arg() callbacks as part of the arg
objects themselves; it makes more sense to just pass these in when the
args are added instead.

Remove the check_arg() callbacks from those objects which also means
removing the check_arg() args from the init functions, adding them to
the add functions and fixing up existing callers.

Signed-off-by: Tom Zanussi <zanussi@kernel.org>
---
 kernel/trace/trace_dynevent.c    | 62 ++++++++++++++++++----------------------
 kernel/trace/trace_dynevent.h    | 11 ++++---
 kernel/trace/trace_events_hist.c | 16 +++++------
 kernel/trace/trace_kprobe.c      | 10 +++----
 4 files changed, 46 insertions(+), 53 deletions(-)

diff --git a/kernel/trace/trace_dynevent.c b/kernel/trace/trace_dynevent.c
index 6ffdbc4fda53..f9cfcdc9d1f3 100644
--- a/kernel/trace/trace_dynevent.c
+++ b/kernel/trace/trace_dynevent.c
@@ -228,27 +228,30 @@ fs_initcall(init_dynamic_event);
  * dynevent_arg_add - Add an arg to a dynevent_cmd
  * @cmd: A pointer to the dynevent_cmd struct representing the new event cmd
  * @arg: The argument to append to the current cmd
+ * @check_arg: An (optional) pointer to a function checking arg sanity
  *
  * Append an argument to a dynevent_cmd.  The argument string will be
  * appended to the current cmd string, followed by a separator, if
- * applicable.  Before the argument is added, the check_arg()
- * function, if defined, is called.
+ * applicable.  Before the argument is added, the @check_arg function,
+ * if present, will be used to check the sanity of the current arg
+ * string.
  *
- * The cmd string, separator, and check_arg() function should be set
- * using the dynevent_arg_init() before any arguments are added using
- * this function.
+ * The cmd string and separator should be set using the
+ * dynevent_arg_init() before any arguments are added using this
+ * function.
  *
  * Return: 0 if successful, error otherwise.
  */
 int dynevent_arg_add(struct dynevent_cmd *cmd,
-		     struct dynevent_arg *arg)
+		     struct dynevent_arg *arg,
+		     dynevent_check_arg_fn_t check_arg)
 {
 	int ret = 0;
 	int delta;
 	char *q;
 
-	if (arg->check_arg) {
-		ret = arg->check_arg(arg);
+	if (check_arg) {
+		ret = check_arg(arg);
 		if (ret)
 			return ret;
 	}
@@ -269,6 +272,7 @@ int dynevent_arg_add(struct dynevent_cmd *cmd,
  * dynevent_arg_pair_add - Add an arg pair to a dynevent_cmd
  * @cmd: A pointer to the dynevent_cmd struct representing the new event cmd
  * @arg_pair: The argument pair to append to the current cmd
+ * @check_arg: An (optional) pointer to a function checking arg sanity
  *
  * Append an argument pair to a dynevent_cmd.  An argument pair
  * consists of a left-hand-side argument and a right-hand-side
@@ -278,24 +282,26 @@ int dynevent_arg_add(struct dynevent_cmd *cmd,
  *
  * The lhs argument string will be appended to the current cmd string,
  * followed by an operator, if applicable, followd by the rhs string,
- * followed finally by a separator, if applicable.  Before anything is
- * added, the check_arg() function, if defined, is called.
+ * followed finally by a separator, if applicable.  Before the
+ * argument is added, the @check_arg function, if present, will be
+ * used to check the sanity of the current arg strings.
  *
- * The cmd strings, operator, separator, and check_arg() function
- * should be set using the dynevent_arg_pair_init() before any arguments
- * are added using this function.
+ * The cmd strings, operator, and separator should be set using the
+ * dynevent_arg_pair_init() before any arguments are added using this
+ * function.
  *
  * Return: 0 if successful, error otherwise.
  */
 int dynevent_arg_pair_add(struct dynevent_cmd *cmd,
-			  struct dynevent_arg_pair *arg_pair)
+			  struct dynevent_arg_pair *arg_pair,
+			  dynevent_check_arg_fn_t check_arg)
 {
 	int ret = 0;
 	int delta;
 	char *q;
 
-	if (arg_pair->check_arg) {
-		ret = arg_pair->check_arg(arg_pair);
+	if (check_arg) {
+		ret = check_arg(arg_pair);
 		if (ret)
 			return ret;
 	}
@@ -385,20 +391,16 @@ void dynevent_cmd_init(struct dynevent_cmd *cmd, char *buf, int maxlen,
 /**
  * dynevent_arg_init - Initialize a dynevent_arg object
  * @arg: A pointer to the dynevent_arg struct representing the arg
- * @check_arg: An (optional) pointer to a function checking arg sanity
  * @separator: An (optional) separator, appended after adding the arg
  *
  * Initialize a dynevent_arg object.  A dynevent_arg represents an
  * object used to append single arguments to the current command
- * string.  The @check_arg function, if present, will be used to check
- * the sanity of the current arg string (which is directly set by the
- * caller).  After the arg string is successfully appended to the
+ * string.  After the arg string is successfully appended to the
  * command string, the optional @separator is appended.  If no
  * separator was specified when initializing the arg, a space will be
  * appended.
  */
 void dynevent_arg_init(struct dynevent_arg *arg,
-		       dynevent_check_arg_fn_t check_arg,
 		       char separator)
 {
 	memset(arg, '\0', sizeof(*arg));
@@ -406,14 +408,11 @@ void dynevent_arg_init(struct dynevent_arg *arg,
 	if (!separator)
 		separator = ' ';
 	arg->separator = separator;
-
-	arg->check_arg = check_arg;
 }
 
 /**
  * dynevent_arg_pair_init - Initialize a dynevent_arg_pair object
  * @arg_pair: A pointer to the dynevent_arg_pair struct representing the arg
- * @check_arg: An (optional) pointer to a function checking arg sanity
  * @operator: An (optional) operator, appended after adding the first arg
  * @separator: An (optional) separator, appended after adding the second arg
  *
@@ -422,16 +421,13 @@ void dynevent_arg_init(struct dynevent_arg *arg,
  * variable_name;' or 'x+y' to the current command string.  An
  * argument pair consists of a left-hand-side argument and a
  * right-hand-side argument separated by an operator, which can be
- * whitespace, all followed by a separator, if applicable. The
- * @check_arg function, if present, will be used to check the sanity
- * of the current arg strings (which is directly set by the caller).
- * After the first arg string is successfully appended to the command
- * string, the optional @operator is appended, followed by the second
- * arg and and optional @separator.  If no separator was specified
- * when initializing the arg, a space will be appended.
+ * whitespace, all followed by a separator, if applicable.  After the
+ * first arg string is successfully appended to the command string,
+ * the optional @operator is appended, followed by the second arg and
+ * and optional @separator.  If no separator was specified when
+ * initializing the arg, a space will be appended.
  */
 void dynevent_arg_pair_init(struct dynevent_arg_pair *arg_pair,
-			    dynevent_check_arg_fn_t check_arg,
 			    char operator, char separator)
 {
 	memset(arg_pair, '\0', sizeof(*arg_pair));
@@ -443,8 +439,6 @@ void dynevent_arg_pair_init(struct dynevent_arg_pair *arg_pair,
 	if (!separator)
 		separator = ' ';
 	arg_pair->separator = separator;
-
-	arg_pair->check_arg = check_arg;
 }
 
 /**
diff --git a/kernel/trace/trace_dynevent.h b/kernel/trace/trace_dynevent.h
index b593fc34c5b1..d6857a254ede 100644
--- a/kernel/trace/trace_dynevent.h
+++ b/kernel/trace/trace_dynevent.h
@@ -126,28 +126,27 @@ typedef int (*dynevent_check_arg_fn_t)(void *data);
 struct dynevent_arg {
 	const char		*str;
 	char			separator; /* e.g. ';', ',', or nothing */
-	dynevent_check_arg_fn_t	check_arg;
 };
 
 extern void dynevent_arg_init(struct dynevent_arg *arg,
-			      dynevent_check_arg_fn_t check_arg,
 			      char separator);
 extern int dynevent_arg_add(struct dynevent_cmd *cmd,
-			    struct dynevent_arg *arg);
+			    struct dynevent_arg *arg,
+			    dynevent_check_arg_fn_t check_arg);
 
 struct dynevent_arg_pair {
 	const char		*lhs;
 	const char		*rhs;
 	char			operator; /* e.g. '=' or nothing */
 	char			separator; /* e.g. ';', ',', or nothing */
-	dynevent_check_arg_fn_t	check_arg;
 };
 
 extern void dynevent_arg_pair_init(struct dynevent_arg_pair *arg_pair,
-				   dynevent_check_arg_fn_t check_arg,
 				   char operator, char separator);
+
 extern int dynevent_arg_pair_add(struct dynevent_cmd *cmd,
-				 struct dynevent_arg_pair *arg_pair);
+				 struct dynevent_arg_pair *arg_pair,
+				 dynevent_check_arg_fn_t check_arg);
 extern int dynevent_str_add(struct dynevent_cmd *cmd, const char *str);
 
 #endif
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 772bd3d7c29f..a566f5d290c1 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -1334,12 +1334,12 @@ int synth_event_add_field(struct dynevent_cmd *cmd, const char *type,
 	if (!type || !name)
 		return -EINVAL;
 
-	dynevent_arg_pair_init(&arg_pair, synth_event_check_arg_fn, 0, ';');
+	dynevent_arg_pair_init(&arg_pair, 0, ';');
 
 	arg_pair.lhs = type;
 	arg_pair.rhs = name;
 
-	ret = dynevent_arg_pair_add(cmd, &arg_pair);
+	ret = dynevent_arg_pair_add(cmd, &arg_pair, synth_event_check_arg_fn);
 	if (ret)
 		return ret;
 
@@ -1377,11 +1377,11 @@ int synth_event_add_field_str(struct dynevent_cmd *cmd, const char *type_name)
 	if (!type_name)
 		return -EINVAL;
 
-	dynevent_arg_init(&arg, NULL, ';');
+	dynevent_arg_init(&arg, ';');
 
 	arg.str = type_name;
 
-	ret = dynevent_arg_add(cmd, &arg);
+	ret = dynevent_arg_add(cmd, &arg, NULL);
 	if (ret)
 		return ret;
 
@@ -1472,9 +1472,9 @@ int __synth_event_gen_cmd_start(struct dynevent_cmd *cmd, const char *name,
 	if (cmd->type != DYNEVENT_TYPE_SYNTH)
 		return -EINVAL;
 
-	dynevent_arg_init(&arg, NULL, 0);
+	dynevent_arg_init(&arg, 0);
 	arg.str = name;
-	ret = dynevent_arg_add(cmd, &arg);
+	ret = dynevent_arg_add(cmd, &arg, NULL);
 	if (ret)
 		return ret;
 
@@ -1546,9 +1546,9 @@ int synth_event_gen_cmd_array_start(struct dynevent_cmd *cmd, const char *name,
 	if (n_fields > SYNTH_FIELDS_MAX)
 		return -EINVAL;
 
-	dynevent_arg_init(&arg, NULL, 0);
+	dynevent_arg_init(&arg, 0);
 	arg.str = name;
-	ret = dynevent_arg_add(cmd, &arg);
+	ret = dynevent_arg_add(cmd, &arg, NULL);
 	if (ret)
 		return ret;
 
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 307abb724a71..fe183d4045d2 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -962,9 +962,9 @@ int __kprobe_event_gen_cmd_start(struct dynevent_cmd *cmd, bool kretprobe,
 	if (ret)
 		return ret;
 
-	dynevent_arg_init(&arg, NULL, 0);
+	dynevent_arg_init(&arg, 0);
 	arg.str = loc;
-	ret = dynevent_arg_add(cmd, &arg);
+	ret = dynevent_arg_add(cmd, &arg, NULL);
 	if (ret)
 		return ret;
 
@@ -982,7 +982,7 @@ int __kprobe_event_gen_cmd_start(struct dynevent_cmd *cmd, bool kretprobe,
 		}
 
 		arg.str = field;
-		ret = dynevent_arg_add(cmd, &arg);
+		ret = dynevent_arg_add(cmd, &arg, NULL);
 		if (ret)
 			break;
 	}
@@ -1017,7 +1017,7 @@ int __kprobe_event_add_fields(struct dynevent_cmd *cmd, ...)
 	if (cmd->type != DYNEVENT_TYPE_KPROBE)
 		return -EINVAL;
 
-	dynevent_arg_init(&arg, NULL, 0);
+	dynevent_arg_init(&arg, 0);
 
 	va_start(args, cmd);
 	for (;;) {
@@ -1033,7 +1033,7 @@ int __kprobe_event_add_fields(struct dynevent_cmd *cmd, ...)
 		}
 
 		arg.str = field;
-		ret = dynevent_arg_add(cmd, &arg);
+		ret = dynevent_arg_add(cmd, &arg, NULL);
 		if (ret)
 			break;
 	}
-- 
2.14.1

Re: [PATCH 2/4] tracing: Remove check_arg() callbacks from dynevent args

[Masami Hiramatsu]

On Fri, 31 Jan 2020 15:55:32 -0600
Tom Zanussi <zanussi@kernel.org> wrote:

> It's kind of strange to have check_arg() callbacks as part of the arg
> objects themselves; it makes more sense to just pass these in when the
> args are added instead.
> 
> Remove the check_arg() callbacks from those objects which also means
> removing the check_arg() args from the init functions, adding them to
> the add functions and fixing up existing callers.

Looks good to me.

Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>

Thank you,

> 
> Signed-off-by: Tom Zanussi <zanussi@kernel.org>
> ---
>  kernel/trace/trace_dynevent.c    | 62 ++++++++++++++++++----------------------
>  kernel/trace/trace_dynevent.h    | 11 ++++---
>  kernel/trace/trace_events_hist.c | 16 +++++------
>  kernel/trace/trace_kprobe.c      | 10 +++----
>  4 files changed, 46 insertions(+), 53 deletions(-)
> 
> diff --git a/kernel/trace/trace_dynevent.c b/kernel/trace/trace_dynevent.c
> index 6ffdbc4fda53..f9cfcdc9d1f3 100644
> --- a/kernel/trace/trace_dynevent.c
> +++ b/kernel/trace/trace_dynevent.c
> @@ -228,27 +228,30 @@ fs_initcall(init_dynamic_event);
>   * dynevent_arg_add - Add an arg to a dynevent_cmd
>   * @cmd: A pointer to the dynevent_cmd struct representing the new event cmd
>   * @arg: The argument to append to the current cmd
> + * @check_arg: An (optional) pointer to a function checking arg sanity
>   *
>   * Append an argument to a dynevent_cmd.  The argument string will be
>   * appended to the current cmd string, followed by a separator, if
> - * applicable.  Before the argument is added, the check_arg()
> - * function, if defined, is called.
> + * applicable.  Before the argument is added, the @check_arg function,
> + * if present, will be used to check the sanity of the current arg
> + * string.
>   *
> - * The cmd string, separator, and check_arg() function should be set
> - * using the dynevent_arg_init() before any arguments are added using
> - * this function.
> + * The cmd string and separator should be set using the
> + * dynevent_arg_init() before any arguments are added using this
> + * function.
>   *
>   * Return: 0 if successful, error otherwise.
>   */
>  int dynevent_arg_add(struct dynevent_cmd *cmd,
> -		     struct dynevent_arg *arg)
> +		     struct dynevent_arg *arg,
> +		     dynevent_check_arg_fn_t check_arg)
>  {
>  	int ret = 0;
>  	int delta;
>  	char *q;
>  
> -	if (arg->check_arg) {
> -		ret = arg->check_arg(arg);
> +	if (check_arg) {
> +		ret = check_arg(arg);
>  		if (ret)
>  			return ret;
>  	}
> @@ -269,6 +272,7 @@ int dynevent_arg_add(struct dynevent_cmd *cmd,
>   * dynevent_arg_pair_add - Add an arg pair to a dynevent_cmd
>   * @cmd: A pointer to the dynevent_cmd struct representing the new event cmd
>   * @arg_pair: The argument pair to append to the current cmd
> + * @check_arg: An (optional) pointer to a function checking arg sanity
>   *
>   * Append an argument pair to a dynevent_cmd.  An argument pair
>   * consists of a left-hand-side argument and a right-hand-side
> @@ -278,24 +282,26 @@ int dynevent_arg_add(struct dynevent_cmd *cmd,
>   *
>   * The lhs argument string will be appended to the current cmd string,
>   * followed by an operator, if applicable, followd by the rhs string,
> - * followed finally by a separator, if applicable.  Before anything is
> - * added, the check_arg() function, if defined, is called.
> + * followed finally by a separator, if applicable.  Before the
> + * argument is added, the @check_arg function, if present, will be
> + * used to check the sanity of the current arg strings.
>   *
> - * The cmd strings, operator, separator, and check_arg() function
> - * should be set using the dynevent_arg_pair_init() before any arguments
> - * are added using this function.
> + * The cmd strings, operator, and separator should be set using the
> + * dynevent_arg_pair_init() before any arguments are added using this
> + * function.
>   *
>   * Return: 0 if successful, error otherwise.
>   */
>  int dynevent_arg_pair_add(struct dynevent_cmd *cmd,
> -			  struct dynevent_arg_pair *arg_pair)
> +			  struct dynevent_arg_pair *arg_pair,
> +			  dynevent_check_arg_fn_t check_arg)
>  {
>  	int ret = 0;
>  	int delta;
>  	char *q;
>  
> -	if (arg_pair->check_arg) {
> -		ret = arg_pair->check_arg(arg_pair);
> +	if (check_arg) {
> +		ret = check_arg(arg_pair);
>  		if (ret)
>  			return ret;
>  	}
> @@ -385,20 +391,16 @@ void dynevent_cmd_init(struct dynevent_cmd *cmd, char *buf, int maxlen,
>  /**
>   * dynevent_arg_init - Initialize a dynevent_arg object
>   * @arg: A pointer to the dynevent_arg struct representing the arg
> - * @check_arg: An (optional) pointer to a function checking arg sanity
>   * @separator: An (optional) separator, appended after adding the arg
>   *
>   * Initialize a dynevent_arg object.  A dynevent_arg represents an
>   * object used to append single arguments to the current command
> - * string.  The @check_arg function, if present, will be used to check
> - * the sanity of the current arg string (which is directly set by the
> - * caller).  After the arg string is successfully appended to the
> + * string.  After the arg string is successfully appended to the
>   * command string, the optional @separator is appended.  If no
>   * separator was specified when initializing the arg, a space will be
>   * appended.
>   */
>  void dynevent_arg_init(struct dynevent_arg *arg,
> -		       dynevent_check_arg_fn_t check_arg,
>  		       char separator)
>  {
>  	memset(arg, '\0', sizeof(*arg));
> @@ -406,14 +408,11 @@ void dynevent_arg_init(struct dynevent_arg *arg,
>  	if (!separator)
>  		separator = ' ';
>  	arg->separator = separator;
> -
> -	arg->check_arg = check_arg;
>  }
>  
>  /**
>   * dynevent_arg_pair_init - Initialize a dynevent_arg_pair object
>   * @arg_pair: A pointer to the dynevent_arg_pair struct representing the arg
> - * @check_arg: An (optional) pointer to a function checking arg sanity
>   * @operator: An (optional) operator, appended after adding the first arg
>   * @separator: An (optional) separator, appended after adding the second arg
>   *
> @@ -422,16 +421,13 @@ void dynevent_arg_init(struct dynevent_arg *arg,
>   * variable_name;' or 'x+y' to the current command string.  An
>   * argument pair consists of a left-hand-side argument and a
>   * right-hand-side argument separated by an operator, which can be
> - * whitespace, all followed by a separator, if applicable. The
> - * @check_arg function, if present, will be used to check the sanity
> - * of the current arg strings (which is directly set by the caller).
> - * After the first arg string is successfully appended to the command
> - * string, the optional @operator is appended, followed by the second
> - * arg and and optional @separator.  If no separator was specified
> - * when initializing the arg, a space will be appended.
> + * whitespace, all followed by a separator, if applicable.  After the
> + * first arg string is successfully appended to the command string,
> + * the optional @operator is appended, followed by the second arg and
> + * and optional @separator.  If no separator was specified when
> + * initializing the arg, a space will be appended.
>   */
>  void dynevent_arg_pair_init(struct dynevent_arg_pair *arg_pair,
> -			    dynevent_check_arg_fn_t check_arg,
>  			    char operator, char separator)
>  {
>  	memset(arg_pair, '\0', sizeof(*arg_pair));
> @@ -443,8 +439,6 @@ void dynevent_arg_pair_init(struct dynevent_arg_pair *arg_pair,
>  	if (!separator)
>  		separator = ' ';
>  	arg_pair->separator = separator;
> -
> -	arg_pair->check_arg = check_arg;
>  }
>  
>  /**
> diff --git a/kernel/trace/trace_dynevent.h b/kernel/trace/trace_dynevent.h
> index b593fc34c5b1..d6857a254ede 100644
> --- a/kernel/trace/trace_dynevent.h
> +++ b/kernel/trace/trace_dynevent.h
> @@ -126,28 +126,27 @@ typedef int (*dynevent_check_arg_fn_t)(void *data);
>  struct dynevent_arg {
>  	const char		*str;
>  	char			separator; /* e.g. ';', ',', or nothing */
> -	dynevent_check_arg_fn_t	check_arg;
>  };
>  
>  extern void dynevent_arg_init(struct dynevent_arg *arg,
> -			      dynevent_check_arg_fn_t check_arg,
>  			      char separator);
>  extern int dynevent_arg_add(struct dynevent_cmd *cmd,
> -			    struct dynevent_arg *arg);
> +			    struct dynevent_arg *arg,
> +			    dynevent_check_arg_fn_t check_arg);
>  
>  struct dynevent_arg_pair {
>  	const char		*lhs;
>  	const char		*rhs;
>  	char			operator; /* e.g. '=' or nothing */
>  	char			separator; /* e.g. ';', ',', or nothing */
> -	dynevent_check_arg_fn_t	check_arg;
>  };
>  
>  extern void dynevent_arg_pair_init(struct dynevent_arg_pair *arg_pair,
> -				   dynevent_check_arg_fn_t check_arg,
>  				   char operator, char separator);
> +
>  extern int dynevent_arg_pair_add(struct dynevent_cmd *cmd,
> -				 struct dynevent_arg_pair *arg_pair);
> +				 struct dynevent_arg_pair *arg_pair,
> +				 dynevent_check_arg_fn_t check_arg);
>  extern int dynevent_str_add(struct dynevent_cmd *cmd, const char *str);
>  
>  #endif
> diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
> index 772bd3d7c29f..a566f5d290c1 100644
> --- a/kernel/trace/trace_events_hist.c
> +++ b/kernel/trace/trace_events_hist.c
> @@ -1334,12 +1334,12 @@ int synth_event_add_field(struct dynevent_cmd *cmd, const char *type,
>  	if (!type || !name)
>  		return -EINVAL;
>  
> -	dynevent_arg_pair_init(&arg_pair, synth_event_check_arg_fn, 0, ';');
> +	dynevent_arg_pair_init(&arg_pair, 0, ';');
>  
>  	arg_pair.lhs = type;
>  	arg_pair.rhs = name;
>  
> -	ret = dynevent_arg_pair_add(cmd, &arg_pair);
> +	ret = dynevent_arg_pair_add(cmd, &arg_pair, synth_event_check_arg_fn);
>  	if (ret)
>  		return ret;
>  
> @@ -1377,11 +1377,11 @@ int synth_event_add_field_str(struct dynevent_cmd *cmd, const char *type_name)
>  	if (!type_name)
>  		return -EINVAL;
>  
> -	dynevent_arg_init(&arg, NULL, ';');
> +	dynevent_arg_init(&arg, ';');
>  
>  	arg.str = type_name;
>  
> -	ret = dynevent_arg_add(cmd, &arg);
> +	ret = dynevent_arg_add(cmd, &arg, NULL);
>  	if (ret)
>  		return ret;
>  
> @@ -1472,9 +1472,9 @@ int __synth_event_gen_cmd_start(struct dynevent_cmd *cmd, const char *name,
>  	if (cmd->type != DYNEVENT_TYPE_SYNTH)
>  		return -EINVAL;
>  
> -	dynevent_arg_init(&arg, NULL, 0);
> +	dynevent_arg_init(&arg, 0);
>  	arg.str = name;
> -	ret = dynevent_arg_add(cmd, &arg);
> +	ret = dynevent_arg_add(cmd, &arg, NULL);
>  	if (ret)
>  		return ret;
>  
> @@ -1546,9 +1546,9 @@ int synth_event_gen_cmd_array_start(struct dynevent_cmd *cmd, const char *name,
>  	if (n_fields > SYNTH_FIELDS_MAX)
>  		return -EINVAL;
>  
> -	dynevent_arg_init(&arg, NULL, 0);
> +	dynevent_arg_init(&arg, 0);
>  	arg.str = name;
> -	ret = dynevent_arg_add(cmd, &arg);
> +	ret = dynevent_arg_add(cmd, &arg, NULL);
>  	if (ret)
>  		return ret;
>  
> diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
> index 307abb724a71..fe183d4045d2 100644
> --- a/kernel/trace/trace_kprobe.c
> +++ b/kernel/trace/trace_kprobe.c
> @@ -962,9 +962,9 @@ int __kprobe_event_gen_cmd_start(struct dynevent_cmd *cmd, bool kretprobe,
>  	if (ret)
>  		return ret;
>  
> -	dynevent_arg_init(&arg, NULL, 0);
> +	dynevent_arg_init(&arg, 0);
>  	arg.str = loc;
> -	ret = dynevent_arg_add(cmd, &arg);
> +	ret = dynevent_arg_add(cmd, &arg, NULL);
>  	if (ret)
>  		return ret;
>  
> @@ -982,7 +982,7 @@ int __kprobe_event_gen_cmd_start(struct dynevent_cmd *cmd, bool kretprobe,
>  		}
>  
>  		arg.str = field;
> -		ret = dynevent_arg_add(cmd, &arg);
> +		ret = dynevent_arg_add(cmd, &arg, NULL);
>  		if (ret)
>  			break;
>  	}
> @@ -1017,7 +1017,7 @@ int __kprobe_event_add_fields(struct dynevent_cmd *cmd, ...)
>  	if (cmd->type != DYNEVENT_TYPE_KPROBE)
>  		return -EINVAL;
>  
> -	dynevent_arg_init(&arg, NULL, 0);
> +	dynevent_arg_init(&arg, 0);
>  
>  	va_start(args, cmd);
>  	for (;;) {
> @@ -1033,7 +1033,7 @@ int __kprobe_event_add_fields(struct dynevent_cmd *cmd, ...)
>  		}
>  
>  		arg.str = field;
> -		ret = dynevent_arg_add(cmd, &arg);
> +		ret = dynevent_arg_add(cmd, &arg, NULL);
>  		if (ret)
>  			break;
>  	}
> -- 
> 2.14.1
> 


-- 
Masami Hiramatsu <mhiramat@kernel.org>

[PATCH 3/4] tracing: Remove useless code in dynevent_arg_pair_add()

[Tom Zanussi]

The final addition to q is unnecessary, since q isn't ever used
afterwards.

Signed-off-by: Tom Zanussi <zanussi@kernel.org>
---
 kernel/trace/trace_dynevent.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/trace/trace_dynevent.c b/kernel/trace/trace_dynevent.c
index f9cfcdc9d1f3..204275ec8d71 100644
--- a/kernel/trace/trace_dynevent.c
+++ b/kernel/trace/trace_dynevent.c
@@ -322,7 +322,7 @@ int dynevent_arg_pair_add(struct dynevent_cmd *cmd,
 		pr_err("field string is too long: %s\n", arg_pair->rhs);
 		return -E2BIG;
 	}
-	cmd->remaining -= delta; q += delta;
+	cmd->remaining -= delta;
 
 	return ret;
 }
-- 
2.14.1

Re: [PATCH 3/4] tracing: Remove useless code in dynevent_arg_pair_add()

[Masami Hiramatsu]

On Fri, 31 Jan 2020 15:55:33 -0600
Tom Zanussi <zanussi@kernel.org> wrote:

> The final addition to q is unnecessary, since q isn't ever used
> afterwards.
> 

Yeah, thanks for updating :)

Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>

Thank you,


> Signed-off-by: Tom Zanussi <zanussi@kernel.org>
> ---
>  kernel/trace/trace_dynevent.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/trace/trace_dynevent.c b/kernel/trace/trace_dynevent.c
> index f9cfcdc9d1f3..204275ec8d71 100644
> --- a/kernel/trace/trace_dynevent.c
> +++ b/kernel/trace/trace_dynevent.c
> @@ -322,7 +322,7 @@ int dynevent_arg_pair_add(struct dynevent_cmd *cmd,
>  		pr_err("field string is too long: %s\n", arg_pair->rhs);
>  		return -E2BIG;
>  	}
> -	cmd->remaining -= delta; q += delta;
> +	cmd->remaining -= delta;
>  
>  	return ret;
>  }
> -- 
> 2.14.1
> 


-- 
Masami Hiramatsu <mhiramat@kernel.org>

[PATCH 4/4] tracing: Use seq_buf for building dynevent_cmd string

[Tom Zanussi]

The dynevent_cmd commands that build up the command string don't need
to do that themselves - there's a seq_buf facility that does pretty
much the same thing those command are doing manually, so use it
instead.

Signed-off-by: Tom Zanussi <zanussi@kernel.org>
---
 include/linux/trace_events.h     |  4 +---
 kernel/trace/trace_dynevent.c    | 48 +++++++++++-----------------------------
 kernel/trace/trace_events_hist.c |  2 +-
 kernel/trace/trace_kprobe.c      |  2 +-
 4 files changed, 16 insertions(+), 40 deletions(-)

diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
index 7c307a7c9c6a..67f528ecb9e5 100644
--- a/include/linux/trace_events.h
+++ b/include/linux/trace_events.h
@@ -367,10 +367,8 @@ struct dynevent_cmd;
 typedef int (*dynevent_create_fn_t)(struct dynevent_cmd *cmd);
 
 struct dynevent_cmd {
-	char			*buf;
+	struct seq_buf		seq;
 	const char		*event_name;
-	int			maxlen;
-	int			remaining;
 	unsigned int		n_fields;
 	enum dynevent_type	type;
 	dynevent_create_fn_t	run_command;
diff --git a/kernel/trace/trace_dynevent.c b/kernel/trace/trace_dynevent.c
index 204275ec8d71..9f2e8520b748 100644
--- a/kernel/trace/trace_dynevent.c
+++ b/kernel/trace/trace_dynevent.c
@@ -247,8 +247,6 @@ int dynevent_arg_add(struct dynevent_cmd *cmd,
 		     dynevent_check_arg_fn_t check_arg)
 {
 	int ret = 0;
-	int delta;
-	char *q;
 
 	if (check_arg) {
 		ret = check_arg(arg);
@@ -256,14 +254,11 @@ int dynevent_arg_add(struct dynevent_cmd *cmd,
 			return ret;
 	}
 
-	q = cmd->buf + (cmd->maxlen - cmd->remaining);
-
-	delta = snprintf(q, cmd->remaining, " %s%c", arg->str, arg->separator);
-	if (delta >= cmd->remaining) {
-		pr_err("String is too long: %s\n", arg->str);
+	ret = seq_buf_printf(&cmd->seq, " %s%c", arg->str, arg->separator);
+	if (ret) {
+		pr_err("String is too long: %s%c\n", arg->str, arg->separator);
 		return -E2BIG;
 	}
-	cmd->remaining -= delta;
 
 	return ret;
 }
@@ -297,8 +292,6 @@ int dynevent_arg_pair_add(struct dynevent_cmd *cmd,
 			  dynevent_check_arg_fn_t check_arg)
 {
 	int ret = 0;
-	int delta;
-	char *q;
 
 	if (check_arg) {
 		ret = check_arg(arg_pair);
@@ -306,23 +299,15 @@ int dynevent_arg_pair_add(struct dynevent_cmd *cmd,
 			return ret;
 	}
 
-	q = cmd->buf + (cmd->maxlen - cmd->remaining);
-
-	delta = snprintf(q, cmd->remaining, " %s%c", arg_pair->lhs,
-			 arg_pair->operator);
-	if (delta >= cmd->remaining) {
-		pr_err("field string is too long: %s\n", arg_pair->lhs);
-		return -E2BIG;
-	}
-	cmd->remaining -= delta; q += delta;
-
-	delta = snprintf(q, cmd->remaining, "%s%c", arg_pair->rhs,
-			 arg_pair->separator);
-	if (delta >= cmd->remaining) {
-		pr_err("field string is too long: %s\n", arg_pair->rhs);
+	ret = seq_buf_printf(&cmd->seq, " %s%c%s%c", arg_pair->lhs,
+			     arg_pair->operator, arg_pair->rhs,
+			     arg_pair->separator);
+	if (ret) {
+		pr_err("field string is too long: %s%c%s%c\n", arg_pair->lhs,
+		       arg_pair->operator, arg_pair->rhs,
+		       arg_pair->separator);
 		return -E2BIG;
 	}
-	cmd->remaining -= delta;
 
 	return ret;
 }
@@ -340,17 +325,12 @@ int dynevent_arg_pair_add(struct dynevent_cmd *cmd,
 int dynevent_str_add(struct dynevent_cmd *cmd, const char *str)
 {
 	int ret = 0;
-	int delta;
-	char *q;
-
-	q = cmd->buf + (cmd->maxlen - cmd->remaining);
 
-	delta = snprintf(q, cmd->remaining, "%s", str);
-	if (delta >= cmd->remaining) {
+	ret = seq_buf_puts(&cmd->seq, str);
+	if (ret) {
 		pr_err("String is too long: %s\n", str);
 		return -E2BIG;
 	}
-	cmd->remaining -= delta;
 
 	return ret;
 }
@@ -381,9 +361,7 @@ void dynevent_cmd_init(struct dynevent_cmd *cmd, char *buf, int maxlen,
 {
 	memset(cmd, '\0', sizeof(*cmd));
 
-	cmd->buf = buf;
-	cmd->maxlen = maxlen;
-	cmd->remaining = cmd->maxlen;
+	seq_buf_init(&cmd->seq, buf, maxlen);
 	cmd->type = type;
 	cmd->run_command = run_command;
 }
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index a566f5d290c1..6dc3078a6d02 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -1762,7 +1762,7 @@ static int synth_event_run_command(struct dynevent_cmd *cmd)
 	struct synth_event *se;
 	int ret;
 
-	ret = trace_run_command(cmd->buf, create_or_delete_synth_event);
+	ret = trace_run_command(cmd->seq.buffer, create_or_delete_synth_event);
 	if (ret)
 		return ret;
 
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index fe183d4045d2..51efc790aea8 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -903,7 +903,7 @@ static int create_or_delete_trace_kprobe(int argc, char **argv)
 
 static int trace_kprobe_run_command(struct dynevent_cmd *cmd)
 {
-	return trace_run_command(cmd->buf, create_or_delete_trace_kprobe);
+	return trace_run_command(cmd->seq.buffer, create_or_delete_trace_kprobe);
 }
 
 /**
-- 
2.14.1

Re: [PATCH 4/4] tracing: Use seq_buf for building dynevent_cmd string

[Masami Hiramatsu]

On Fri, 31 Jan 2020 15:55:34 -0600
Tom Zanussi <zanussi@kernel.org> wrote:

> The dynevent_cmd commands that build up the command string don't need
> to do that themselves - there's a seq_buf facility that does pretty
> much the same thing those command are doing manually, so use it
> instead.

Looks so neat :)

Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>

Thank you,

> 
> Signed-off-by: Tom Zanussi <zanussi@kernel.org>
> ---
>  include/linux/trace_events.h     |  4 +---
>  kernel/trace/trace_dynevent.c    | 48 +++++++++++-----------------------------
>  kernel/trace/trace_events_hist.c |  2 +-
>  kernel/trace/trace_kprobe.c      |  2 +-
>  4 files changed, 16 insertions(+), 40 deletions(-)
> 
> diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
> index 7c307a7c9c6a..67f528ecb9e5 100644
> --- a/include/linux/trace_events.h
> +++ b/include/linux/trace_events.h
> @@ -367,10 +367,8 @@ struct dynevent_cmd;
>  typedef int (*dynevent_create_fn_t)(struct dynevent_cmd *cmd);
>  
>  struct dynevent_cmd {
> -	char			*buf;
> +	struct seq_buf		seq;
>  	const char		*event_name;
> -	int			maxlen;
> -	int			remaining;
>  	unsigned int		n_fields;
>  	enum dynevent_type	type;
>  	dynevent_create_fn_t	run_command;
> diff --git a/kernel/trace/trace_dynevent.c b/kernel/trace/trace_dynevent.c
> index 204275ec8d71..9f2e8520b748 100644
> --- a/kernel/trace/trace_dynevent.c
> +++ b/kernel/trace/trace_dynevent.c
> @@ -247,8 +247,6 @@ int dynevent_arg_add(struct dynevent_cmd *cmd,
>  		     dynevent_check_arg_fn_t check_arg)
>  {
>  	int ret = 0;
> -	int delta;
> -	char *q;
>  
>  	if (check_arg) {
>  		ret = check_arg(arg);
> @@ -256,14 +254,11 @@ int dynevent_arg_add(struct dynevent_cmd *cmd,
>  			return ret;
>  	}
>  
> -	q = cmd->buf + (cmd->maxlen - cmd->remaining);
> -
> -	delta = snprintf(q, cmd->remaining, " %s%c", arg->str, arg->separator);
> -	if (delta >= cmd->remaining) {
> -		pr_err("String is too long: %s\n", arg->str);
> +	ret = seq_buf_printf(&cmd->seq, " %s%c", arg->str, arg->separator);
> +	if (ret) {
> +		pr_err("String is too long: %s%c\n", arg->str, arg->separator);
>  		return -E2BIG;
>  	}
> -	cmd->remaining -= delta;
>  
>  	return ret;
>  }
> @@ -297,8 +292,6 @@ int dynevent_arg_pair_add(struct dynevent_cmd *cmd,
>  			  dynevent_check_arg_fn_t check_arg)
>  {
>  	int ret = 0;
> -	int delta;
> -	char *q;
>  
>  	if (check_arg) {
>  		ret = check_arg(arg_pair);
> @@ -306,23 +299,15 @@ int dynevent_arg_pair_add(struct dynevent_cmd *cmd,
>  			return ret;
>  	}
>  
> -	q = cmd->buf + (cmd->maxlen - cmd->remaining);
> -
> -	delta = snprintf(q, cmd->remaining, " %s%c", arg_pair->lhs,
> -			 arg_pair->operator);
> -	if (delta >= cmd->remaining) {
> -		pr_err("field string is too long: %s\n", arg_pair->lhs);
> -		return -E2BIG;
> -	}
> -	cmd->remaining -= delta; q += delta;
> -
> -	delta = snprintf(q, cmd->remaining, "%s%c", arg_pair->rhs,
> -			 arg_pair->separator);
> -	if (delta >= cmd->remaining) {
> -		pr_err("field string is too long: %s\n", arg_pair->rhs);
> +	ret = seq_buf_printf(&cmd->seq, " %s%c%s%c", arg_pair->lhs,
> +			     arg_pair->operator, arg_pair->rhs,
> +			     arg_pair->separator);
> +	if (ret) {
> +		pr_err("field string is too long: %s%c%s%c\n", arg_pair->lhs,
> +		       arg_pair->operator, arg_pair->rhs,
> +		       arg_pair->separator);
>  		return -E2BIG;
>  	}
> -	cmd->remaining -= delta;
>  
>  	return ret;
>  }
> @@ -340,17 +325,12 @@ int dynevent_arg_pair_add(struct dynevent_cmd *cmd,
>  int dynevent_str_add(struct dynevent_cmd *cmd, const char *str)
>  {
>  	int ret = 0;
> -	int delta;
> -	char *q;
> -
> -	q = cmd->buf + (cmd->maxlen - cmd->remaining);
>  
> -	delta = snprintf(q, cmd->remaining, "%s", str);
> -	if (delta >= cmd->remaining) {
> +	ret = seq_buf_puts(&cmd->seq, str);
> +	if (ret) {
>  		pr_err("String is too long: %s\n", str);
>  		return -E2BIG;
>  	}
> -	cmd->remaining -= delta;
>  
>  	return ret;
>  }
> @@ -381,9 +361,7 @@ void dynevent_cmd_init(struct dynevent_cmd *cmd, char *buf, int maxlen,
>  {
>  	memset(cmd, '\0', sizeof(*cmd));
>  
> -	cmd->buf = buf;
> -	cmd->maxlen = maxlen;
> -	cmd->remaining = cmd->maxlen;
> +	seq_buf_init(&cmd->seq, buf, maxlen);
>  	cmd->type = type;
>  	cmd->run_command = run_command;
>  }
> diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
> index a566f5d290c1..6dc3078a6d02 100644
> --- a/kernel/trace/trace_events_hist.c
> +++ b/kernel/trace/trace_events_hist.c
> @@ -1762,7 +1762,7 @@ static int synth_event_run_command(struct dynevent_cmd *cmd)
>  	struct synth_event *se;
>  	int ret;
>  
> -	ret = trace_run_command(cmd->buf, create_or_delete_synth_event);
> +	ret = trace_run_command(cmd->seq.buffer, create_or_delete_synth_event);
>  	if (ret)
>  		return ret;
>  
> diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
> index fe183d4045d2..51efc790aea8 100644
> --- a/kernel/trace/trace_kprobe.c
> +++ b/kernel/trace/trace_kprobe.c
> @@ -903,7 +903,7 @@ static int create_or_delete_trace_kprobe(int argc, char **argv)
>  
>  static int trace_kprobe_run_command(struct dynevent_cmd *cmd)
>  {
> -	return trace_run_command(cmd->buf, create_or_delete_trace_kprobe);
> +	return trace_run_command(cmd->seq.buffer, create_or_delete_trace_kprobe);
>  }
>  
>  /**
> -- 
> 2.14.1
> 


-- 
Masami Hiramatsu <mhiramat@kernel.org>