[PATCH v2] tracing: Allow execnames to be passed as args for synthetic events

[PATCH v2] tracing: Allow execnames to be passed as args for synthetic events

[Steven Rostedt]

From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>

Allow common_pid.execname to be saved in a variable in one histogram to be
passed to another histogram that can pass it as a parameter to a synthetic
event.

 ># echo 'hist:keys=pid:__arg__1=common_timestamp.usecs:arg2=common_pid.execname' \
       > events/sched/sched_waking/trigger
 ># echo 'wakeup_lat s32 pid; u64 delta; char wake_comm[]' > synthetic_events
 ># echo 'hist:keys=next_pid:pid=next_pid,delta=common_timestamp.usecs-$__arg__1,exec=$arg2'\
':onmatch(sched.sched_waking).trace(wakeup_lat,$pid,$delta,$exec)' \
 > events/sched/sched_switch/trigger

The above is a wake up latency synthetic event setup that passes the execname
of the common_pid that woke the task to the scheduling of that task, which
triggers a synthetic event that passes the original execname as a
parameter to display it.

 ># echo 1 > events/synthetic/enable
 ># cat trace
    <idle>-0       [006] d..4   186.863801: wakeup_lat: pid=1306 delta=65 wake_comm=kworker/u16:3
    <idle>-0       [000] d..4   186.863858: wakeup_lat: pid=163 delta=27 wake_comm=<idle>
    <idle>-0       [001] d..4   186.863903: wakeup_lat: pid=1307 delta=36 wake_comm=kworker/u16:4
    <idle>-0       [000] d..4   186.863927: wakeup_lat: pid=163 delta=5 wake_comm=<idle>
    <idle>-0       [006] d..4   186.863957: wakeup_lat: pid=1306 delta=24 wake_comm=kworker/u16:3
      sshd-1306    [006] d..4   186.864051: wakeup_lat: pid=61 delta=62 wake_comm=<idle>
    <idle>-0       [000] d..4   186.965030: wakeup_lat: pid=609 delta=18 wake_comm=<idle>
    <idle>-0       [006] d..4   186.987582: wakeup_lat: pid=1306 delta=65 wake_comm=kworker/u16:3
    <idle>-0       [000] d..4   186.987639: wakeup_lat: pid=163 delta=27 wake_comm=<idle>

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
Changes since v1:
  - Hit a bug on freeing the histogram, found that I used "char[]" for the
    type, and it expects to be freed. Freed the old "type" and still use
    "char[]" but have the normal freeing use kfree_const() on type.

 kernel/trace/trace_events_hist.c | 49 ++++++++++++++++++++++++++++----
 1 file changed, 44 insertions(+), 5 deletions(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 34325f41ebc0..bb1956efd5ef 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -1395,17 +1395,17 @@ static int hist_trigger_elt_data_alloc(struct tracing_map_elt *elt)
 	struct hist_trigger_data *hist_data = elt->map->private_data;
 	unsigned int size = TASK_COMM_LEN;
 	struct hist_elt_data *elt_data;
-	struct hist_field *key_field;
+	struct hist_field *hist_field;
 	unsigned int i, n_str;
 
 	elt_data = kzalloc(sizeof(*elt_data), GFP_KERNEL);
 	if (!elt_data)
 		return -ENOMEM;
 
-	for_each_hist_key_field(i, hist_data) {
-		key_field = hist_data->fields[i];
+	for_each_hist_field(i, hist_data) {
+		hist_field = hist_data->fields[i];
 
-		if (key_field->flags & HIST_FIELD_FL_EXECNAME) {
+		if (hist_field->flags & HIST_FIELD_FL_EXECNAME) {
 			elt_data->comm = kzalloc(size, GFP_KERNEL);
 			if (!elt_data->comm) {
 				kfree(elt_data);
@@ -1589,7 +1589,9 @@ static void __destroy_hist_field(struct hist_field *hist_field)
 
 	kfree(hist_field->var.name);
 	kfree(hist_field->name);
-	kfree(hist_field->type);
+
+	/* execname vars use a constant type */
+	kfree_const(hist_field->type);
 
 	kfree(hist_field->system);
 	kfree(hist_field->event_name);
@@ -3707,6 +3709,40 @@ static int create_val_field(struct hist_trigger_data *hist_data,
 	return __create_val_field(hist_data, val_idx, file, NULL, field_str, 0);
 }
 
+static const char *no_comm = "(no comm)";
+
+static u64 hist_field_execname(struct hist_field *hist_field,
+			       struct tracing_map_elt *elt,
+			       struct trace_buffer *buffer,
+			       struct ring_buffer_event *rbe,
+			       void *event)
+{
+	struct hist_elt_data *elt_data;
+
+	if (WARN_ON_ONCE(!elt))
+		return (u64)(unsigned long)no_comm;
+
+	elt_data = elt->private_data;
+
+	if (WARN_ON_ONCE(!elt_data->comm))
+		return (u64)(unsigned long)no_comm;
+
+	return (u64)(unsigned long)(elt_data->comm);
+}
+
+/* Convert a var that points to common_pid.execname to a string */
+static void update_var_execname(struct hist_field *hist_field)
+{
+	hist_field->flags = HIST_FIELD_FL_STRING | HIST_FIELD_FL_VAR |
+		HIST_FIELD_FL_EXECNAME;
+	hist_field->size = MAX_FILTER_STR_VAL;
+	hist_field->is_signed = 0;
+	kfree(hist_field->type);
+	/* This uses kfree_const() to free */
+	hist_field->type = "char[]";
+	hist_field->fn = hist_field_execname;
+}
+
 static int create_var_field(struct hist_trigger_data *hist_data,
 			    unsigned int val_idx,
 			    struct trace_event_file *file,
@@ -3731,6 +3767,9 @@ static int create_var_field(struct hist_trigger_data *hist_data,
 
 	ret = __create_val_field(hist_data, val_idx, file, var_name, expr_str, flags);
 
+	if (!ret && hist_data->fields[val_idx]->flags & HIST_FIELD_FL_EXECNAME)
+		update_var_execname(hist_data->fields[val_idx]);
+
 	if (!ret && hist_data->fields[val_idx]->flags & HIST_FIELD_FL_STRING)
 		hist_data->fields[val_idx]->var_str_idx = hist_data->n_var_str++;
 
-- 
2.31.1

Re: [PATCH v2] tracing: Allow execnames to be passed as args for synthetic events

[Masami Hiramatsu]

On Wed, 21 Jul 2021 21:47:02 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:

> From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
> 
> Allow common_pid.execname to be saved in a variable in one histogram to be
> passed to another histogram that can pass it as a parameter to a synthetic
> event.
> 
>  ># echo 'hist:keys=pid:__arg__1=common_timestamp.usecs:arg2=common_pid.execname' \
>        > events/sched/sched_waking/trigger
>  ># echo 'wakeup_lat s32 pid; u64 delta; char wake_comm[]' > synthetic_events
>  ># echo 'hist:keys=next_pid:pid=next_pid,delta=common_timestamp.usecs-$__arg__1,exec=$arg2'\
> ':onmatch(sched.sched_waking).trace(wakeup_lat,$pid,$delta,$exec)' \
>  > events/sched/sched_switch/trigger
> 
> The above is a wake up latency synthetic event setup that passes the execname
> of the common_pid that woke the task to the scheduling of that task, which
> triggers a synthetic event that passes the original execname as a
> parameter to display it.
> 
>  ># echo 1 > events/synthetic/enable
>  ># cat trace
>     <idle>-0       [006] d..4   186.863801: wakeup_lat: pid=1306 delta=65 wake_comm=kworker/u16:3
>     <idle>-0       [000] d..4   186.863858: wakeup_lat: pid=163 delta=27 wake_comm=<idle>
>     <idle>-0       [001] d..4   186.863903: wakeup_lat: pid=1307 delta=36 wake_comm=kworker/u16:4
>     <idle>-0       [000] d..4   186.863927: wakeup_lat: pid=163 delta=5 wake_comm=<idle>
>     <idle>-0       [006] d..4   186.863957: wakeup_lat: pid=1306 delta=24 wake_comm=kworker/u16:3
>       sshd-1306    [006] d..4   186.864051: wakeup_lat: pid=61 delta=62 wake_comm=<idle>
>     <idle>-0       [000] d..4   186.965030: wakeup_lat: pid=609 delta=18 wake_comm=<idle>
>     <idle>-0       [006] d..4   186.987582: wakeup_lat: pid=1306 delta=65 wake_comm=kworker/u16:3
>     <idle>-0       [000] d..4   186.987639: wakeup_lat: pid=163 delta=27 wake_comm=<idle>
> 

This looks an interesting improvement. If we can do this, can we also filter
the event by 'comm' (or execname)? 

> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
> ---
> Changes since v1:
>   - Hit a bug on freeing the histogram, found that I used "char[]" for the
>     type, and it expects to be freed. Freed the old "type" and still use
>     "char[]" but have the normal freeing use kfree_const() on type.


BTW, if we can use this technic on the hist_field->type, we can cleanup 
other type = strdup("<any const type>", GFP_KERNEL) with type = "<any const type>" ?

Anyway, that will be done in another patch (I think that should be done first,
then we can avoid an odd kfree() in update_var_execname().)

Thank you,

> 
>  kernel/trace/trace_events_hist.c | 49 ++++++++++++++++++++++++++++----
>  1 file changed, 44 insertions(+), 5 deletions(-)
> 
> diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
> index 34325f41ebc0..bb1956efd5ef 100644
> --- a/kernel/trace/trace_events_hist.c
> +++ b/kernel/trace/trace_events_hist.c
> @@ -1395,17 +1395,17 @@ static int hist_trigger_elt_data_alloc(struct tracing_map_elt *elt)
>  	struct hist_trigger_data *hist_data = elt->map->private_data;
>  	unsigned int size = TASK_COMM_LEN;
>  	struct hist_elt_data *elt_data;
> -	struct hist_field *key_field;
> +	struct hist_field *hist_field;
>  	unsigned int i, n_str;
>  
>  	elt_data = kzalloc(sizeof(*elt_data), GFP_KERNEL);
>  	if (!elt_data)
>  		return -ENOMEM;
>  
> -	for_each_hist_key_field(i, hist_data) {
> -		key_field = hist_data->fields[i];
> +	for_each_hist_field(i, hist_data) {
> +		hist_field = hist_data->fields[i];
>  
> -		if (key_field->flags & HIST_FIELD_FL_EXECNAME) {
> +		if (hist_field->flags & HIST_FIELD_FL_EXECNAME) {
>  			elt_data->comm = kzalloc(size, GFP_KERNEL);
>  			if (!elt_data->comm) {
>  				kfree(elt_data);
> @@ -1589,7 +1589,9 @@ static void __destroy_hist_field(struct hist_field *hist_field)
>  
>  	kfree(hist_field->var.name);
>  	kfree(hist_field->name);
> -	kfree(hist_field->type);
> +
> +	/* execname vars use a constant type */
> +	kfree_const(hist_field->type);
>  
>  	kfree(hist_field->system);
>  	kfree(hist_field->event_name);
> @@ -3707,6 +3709,40 @@ static int create_val_field(struct hist_trigger_data *hist_data,
>  	return __create_val_field(hist_data, val_idx, file, NULL, field_str, 0);
>  }
>  
> +static const char *no_comm = "(no comm)";
> +
> +static u64 hist_field_execname(struct hist_field *hist_field,
> +			       struct tracing_map_elt *elt,
> +			       struct trace_buffer *buffer,
> +			       struct ring_buffer_event *rbe,
> +			       void *event)
> +{
> +	struct hist_elt_data *elt_data;
> +
> +	if (WARN_ON_ONCE(!elt))
> +		return (u64)(unsigned long)no_comm;
> +
> +	elt_data = elt->private_data;
> +
> +	if (WARN_ON_ONCE(!elt_data->comm))
> +		return (u64)(unsigned long)no_comm;
> +
> +	return (u64)(unsigned long)(elt_data->comm);
> +}
> +
> +/* Convert a var that points to common_pid.execname to a string */
> +static void update_var_execname(struct hist_field *hist_field)
> +{
> +	hist_field->flags = HIST_FIELD_FL_STRING | HIST_FIELD_FL_VAR |
> +		HIST_FIELD_FL_EXECNAME;
> +	hist_field->size = MAX_FILTER_STR_VAL;
> +	hist_field->is_signed = 0;
> +	kfree(hist_field->type);
> +	/* This uses kfree_const() to free */
> +	hist_field->type = "char[]";
> +	hist_field->fn = hist_field_execname;
> +}
> +
>  static int create_var_field(struct hist_trigger_data *hist_data,
>  			    unsigned int val_idx,
>  			    struct trace_event_file *file,
> @@ -3731,6 +3767,9 @@ static int create_var_field(struct hist_trigger_data *hist_data,
>  
>  	ret = __create_val_field(hist_data, val_idx, file, var_name, expr_str, flags);
>  
> +	if (!ret && hist_data->fields[val_idx]->flags & HIST_FIELD_FL_EXECNAME)
> +		update_var_execname(hist_data->fields[val_idx]);
> +
>  	if (!ret && hist_data->fields[val_idx]->flags & HIST_FIELD_FL_STRING)
>  		hist_data->fields[val_idx]->var_str_idx = hist_data->n_var_str++;
>  
> -- 
> 2.31.1
> 


-- 
Masami Hiramatsu <mhiramat@kernel.org>

Re: [PATCH v2] tracing: Allow execnames to be passed as args for synthetic events

[Steven Rostedt]

On Thu, 22 Jul 2021 22:29:24 +0900
Masami Hiramatsu <mhiramat@kernel.org> wrote:

> This looks an interesting improvement. If we can do this, can we also filter
> the event by 'comm' (or execname)? 

We would be able to filter on the synthetic event, just like any other
event with a comm (or other string) But I don't think we can filter
before (that is, in the histogram code).

> 
> > Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
> > ---
> > Changes since v1:
> >   - Hit a bug on freeing the histogram, found that I used "char[]" for the
> >     type, and it expects to be freed. Freed the old "type" and still use
> >     "char[]" but have the normal freeing use kfree_const() on type.  
> 
> 
> BTW, if we can use this technic on the hist_field->type, we can cleanup 
> other type = strdup("<any const type>", GFP_KERNEL) with type = "<any const type>" ?
> 
> Anyway, that will be done in another patch (I think that should be done first,
> then we can avoid an odd kfree() in update_var_execname().)

You mean like this? It was done after the patch, but I can move it first.

-- Steve

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index bb1956efd5ef..6b9e4fb70bc1 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -1590,7 +1590,7 @@ static void __destroy_hist_field(struct hist_field *hist_field)
 	kfree(hist_field->var.name);
 	kfree(hist_field->name);
 
-	/* execname vars use a constant type */
+	/* Can likely be a const */
 	kfree_const(hist_field->type);
 
 	kfree(hist_field->system);
@@ -1648,9 +1648,7 @@ static struct hist_field *create_hist_field(struct hist_trigger_data *hist_data,
 	if (flags & HIST_FIELD_FL_HITCOUNT) {
 		hist_field->fn = hist_field_counter;
 		hist_field->size = sizeof(u64);
-		hist_field->type = kstrdup("u64", GFP_KERNEL);
-		if (!hist_field->type)
-			goto free;
+		hist_field->type = "u64";
 		goto out;
 	}
 
@@ -1664,7 +1662,7 @@ static struct hist_field *create_hist_field(struct hist_trigger_data *hist_data,
 		hist_field->fn = hist_field_log2;
 		hist_field->operands[0] = create_hist_field(hist_data, field, fl, NULL);
 		hist_field->size = hist_field->operands[0]->size;
-		hist_field->type = kstrdup(hist_field->operands[0]->type, GFP_KERNEL);
+		hist_field->type = kstrdup_const(hist_field->operands[0]->type, GFP_KERNEL);
 		if (!hist_field->type)
 			goto free;
 		goto out;
@@ -1673,18 +1671,14 @@ static struct hist_field *create_hist_field(struct hist_trigger_data *hist_data,
 	if (flags & HIST_FIELD_FL_TIMESTAMP) {
 		hist_field->fn = hist_field_timestamp;
 		hist_field->size = sizeof(u64);
-		hist_field->type = kstrdup("u64", GFP_KERNEL);
-		if (!hist_field->type)
-			goto free;
+		hist_field->type = "u64";
 		goto out;
 	}
 
 	if (flags & HIST_FIELD_FL_CPU) {
 		hist_field->fn = hist_field_cpu;
 		hist_field->size = sizeof(int);
-		hist_field->type = kstrdup("unsigned int", GFP_KERNEL);
-		if (!hist_field->type)
-			goto free;
+		hist_field->type = "unsigned int";
 		goto out;
 	}
 
@@ -1697,7 +1691,7 @@ static struct hist_field *create_hist_field(struct hist_trigger_data *hist_data,
 		flags |= HIST_FIELD_FL_STRING;
 
 		hist_field->size = MAX_FILTER_STR_VAL;
-		hist_field->type = kstrdup(field->type, GFP_KERNEL);
+		hist_field->type = kstrdup_const(field->type, GFP_KERNEL);
 		if (!hist_field->type)
 			goto free;
 
@@ -1710,7 +1704,7 @@ static struct hist_field *create_hist_field(struct hist_trigger_data *hist_data,
 	} else {
 		hist_field->size = field->size;
 		hist_field->is_signed = field->is_signed;
-		hist_field->type = kstrdup(field->type, GFP_KERNEL);
+		hist_field->type = kstrdup_const(field->type, GFP_KERNEL);
 		if (!hist_field->type)
 			goto free;
 
@@ -1796,7 +1790,7 @@ static int init_var_ref(struct hist_field *ref_field,
 		}
 	}
 
-	ref_field->type = kstrdup(var_field->type, GFP_KERNEL);
+	ref_field->type = kstrdup_const(var_field->type, GFP_KERNEL);
 	if (!ref_field->type) {
 		err = -ENOMEM;
 		goto free;
@@ -2165,7 +2159,7 @@ static struct hist_field *parse_unary(struct hist_trigger_data *hist_data,
 	expr->operands[0] = operand1;
 	expr->operator = FIELD_OP_UNARY_MINUS;
 	expr->name = expr_str(expr, 0);
-	expr->type = kstrdup(operand1->type, GFP_KERNEL);
+	expr->type = kstrdup_const(operand1->type, GFP_KERNEL);
 	if (!expr->type) {
 		ret = -ENOMEM;
 		goto free;
@@ -2291,7 +2285,7 @@ static struct hist_field *parse_expr(struct hist_trigger_data *hist_data,
 	expr->operands[1] = operand2;
 	expr->operator = field_op;
 	expr->name = expr_str(expr, 0);
-	expr->type = kstrdup(operand1->type, GFP_KERNEL);
+	expr->type = kstrdup_const(operand1->type, GFP_KERNEL);
 	if (!expr->type) {
 		ret = -ENOMEM;
 		goto free;
@@ -2679,10 +2673,10 @@ static struct hist_field *create_var(struct hist_trigger_data *hist_data,
 	var->var.hist_data = var->hist_data = hist_data;
 	var->size = size;
 	var->var.name = kstrdup(name, GFP_KERNEL);
-	var->type = kstrdup(type, GFP_KERNEL);
+	var->type = kstrdup_const(type, GFP_KERNEL);
 	if (!var->var.name || !var->type) {
 		kfree(var->var.name);
-		kfree(var->type);
+		kfree_const(var->type);
 		kfree(var);
 		var = ERR_PTR(-ENOMEM);
 	}

Re: [PATCH v2] tracing: Allow execnames to be passed as args for synthetic events

[Masami Hiramatsu]

On Thu, 22 Jul 2021 09:46:38 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:

> On Thu, 22 Jul 2021 22:29:24 +0900
> Masami Hiramatsu <mhiramat@kernel.org> wrote:
> 
> > This looks an interesting improvement. If we can do this, can we also filter
> > the event by 'comm' (or execname)? 
> 
> We would be able to filter on the synthetic event, just like any other
> event with a comm (or other string) But I don't think we can filter
> before (that is, in the histogram code).
> 
> > 
> > > Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
> > > ---
> > > Changes since v1:
> > >   - Hit a bug on freeing the histogram, found that I used "char[]" for the
> > >     type, and it expects to be freed. Freed the old "type" and still use
> > >     "char[]" but have the normal freeing use kfree_const() on type.  
> > 
> > 
> > BTW, if we can use this technic on the hist_field->type, we can cleanup 
> > other type = strdup("<any const type>", GFP_KERNEL) with type = "<any const type>" ?
> > 
> > Anyway, that will be done in another patch (I think that should be done first,
> > then we can avoid an odd kfree() in update_var_execname().)
> 
> You mean like this? It was done after the patch, but I can move it first.

Yes, this looks good to me.

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

Thank you,

> 
> -- Steve
> 
> diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
> index bb1956efd5ef..6b9e4fb70bc1 100644
> --- a/kernel/trace/trace_events_hist.c
> +++ b/kernel/trace/trace_events_hist.c
> @@ -1590,7 +1590,7 @@ static void __destroy_hist_field(struct hist_field *hist_field)
>  	kfree(hist_field->var.name);
>  	kfree(hist_field->name);
>  
> -	/* execname vars use a constant type */
> +	/* Can likely be a const */
>  	kfree_const(hist_field->type);
>  
>  	kfree(hist_field->system);
> @@ -1648,9 +1648,7 @@ static struct hist_field *create_hist_field(struct hist_trigger_data *hist_data,
>  	if (flags & HIST_FIELD_FL_HITCOUNT) {
>  		hist_field->fn = hist_field_counter;
>  		hist_field->size = sizeof(u64);
> -		hist_field->type = kstrdup("u64", GFP_KERNEL);
> -		if (!hist_field->type)
> -			goto free;
> +		hist_field->type = "u64";
>  		goto out;
>  	}
>  
> @@ -1664,7 +1662,7 @@ static struct hist_field *create_hist_field(struct hist_trigger_data *hist_data,
>  		hist_field->fn = hist_field_log2;
>  		hist_field->operands[0] = create_hist_field(hist_data, field, fl, NULL);
>  		hist_field->size = hist_field->operands[0]->size;
> -		hist_field->type = kstrdup(hist_field->operands[0]->type, GFP_KERNEL);
> +		hist_field->type = kstrdup_const(hist_field->operands[0]->type, GFP_KERNEL);
>  		if (!hist_field->type)
>  			goto free;
>  		goto out;
> @@ -1673,18 +1671,14 @@ static struct hist_field *create_hist_field(struct hist_trigger_data *hist_data,
>  	if (flags & HIST_FIELD_FL_TIMESTAMP) {
>  		hist_field->fn = hist_field_timestamp;
>  		hist_field->size = sizeof(u64);
> -		hist_field->type = kstrdup("u64", GFP_KERNEL);
> -		if (!hist_field->type)
> -			goto free;
> +		hist_field->type = "u64";
>  		goto out;
>  	}
>  
>  	if (flags & HIST_FIELD_FL_CPU) {
>  		hist_field->fn = hist_field_cpu;
>  		hist_field->size = sizeof(int);
> -		hist_field->type = kstrdup("unsigned int", GFP_KERNEL);
> -		if (!hist_field->type)
> -			goto free;
> +		hist_field->type = "unsigned int";
>  		goto out;
>  	}
>  
> @@ -1697,7 +1691,7 @@ static struct hist_field *create_hist_field(struct hist_trigger_data *hist_data,
>  		flags |= HIST_FIELD_FL_STRING;
>  
>  		hist_field->size = MAX_FILTER_STR_VAL;
> -		hist_field->type = kstrdup(field->type, GFP_KERNEL);
> +		hist_field->type = kstrdup_const(field->type, GFP_KERNEL);
>  		if (!hist_field->type)
>  			goto free;
>  
> @@ -1710,7 +1704,7 @@ static struct hist_field *create_hist_field(struct hist_trigger_data *hist_data,
>  	} else {
>  		hist_field->size = field->size;
>  		hist_field->is_signed = field->is_signed;
> -		hist_field->type = kstrdup(field->type, GFP_KERNEL);
> +		hist_field->type = kstrdup_const(field->type, GFP_KERNEL);
>  		if (!hist_field->type)
>  			goto free;
>  
> @@ -1796,7 +1790,7 @@ static int init_var_ref(struct hist_field *ref_field,
>  		}
>  	}
>  
> -	ref_field->type = kstrdup(var_field->type, GFP_KERNEL);
> +	ref_field->type = kstrdup_const(var_field->type, GFP_KERNEL);
>  	if (!ref_field->type) {
>  		err = -ENOMEM;
>  		goto free;
> @@ -2165,7 +2159,7 @@ static struct hist_field *parse_unary(struct hist_trigger_data *hist_data,
>  	expr->operands[0] = operand1;
>  	expr->operator = FIELD_OP_UNARY_MINUS;
>  	expr->name = expr_str(expr, 0);
> -	expr->type = kstrdup(operand1->type, GFP_KERNEL);
> +	expr->type = kstrdup_const(operand1->type, GFP_KERNEL);
>  	if (!expr->type) {
>  		ret = -ENOMEM;
>  		goto free;
> @@ -2291,7 +2285,7 @@ static struct hist_field *parse_expr(struct hist_trigger_data *hist_data,
>  	expr->operands[1] = operand2;
>  	expr->operator = field_op;
>  	expr->name = expr_str(expr, 0);
> -	expr->type = kstrdup(operand1->type, GFP_KERNEL);
> +	expr->type = kstrdup_const(operand1->type, GFP_KERNEL);
>  	if (!expr->type) {
>  		ret = -ENOMEM;
>  		goto free;
> @@ -2679,10 +2673,10 @@ static struct hist_field *create_var(struct hist_trigger_data *hist_data,
>  	var->var.hist_data = var->hist_data = hist_data;
>  	var->size = size;
>  	var->var.name = kstrdup(name, GFP_KERNEL);
> -	var->type = kstrdup(type, GFP_KERNEL);
> +	var->type = kstrdup_const(type, GFP_KERNEL);
>  	if (!var->var.name || !var->type) {
>  		kfree(var->var.name);
> -		kfree(var->type);
> +		kfree_const(var->type);
>  		kfree(var);
>  		var = ERR_PTR(-ENOMEM);
>  	}


-- 
Masami Hiramatsu <mhiramat@kernel.org>