linux-kernel - Re: [PATCH v8 03/12] user_events: Handle matching arguments from dyn

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Date:   Wed, 22 Dec 2021 15:19:02 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Beau Belgrave <beaub@...ux.microsoft.com>
Cc:     rostedt@...dmis.org, linux-trace-devel@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v8 03/12] user_events: Handle matching arguments from
 dyn_events

On Thu, 16 Dec 2021 09:35:02 -0800
Beau Belgrave <beaub@...ux.microsoft.com> wrote:

> Ensures that when dynamic events requests a match with arguments that
> they match what is in the user_event.
> 

Looks good to me.

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

Thank you,

> Signed-off-by: Beau Belgrave <beaub@...ux.microsoft.com>
> ---
>  kernel/trace/trace_events_user.c | 77 +++++++++++++++++++++++++++++++-
>  1 file changed, 76 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/trace/trace_events_user.c b/kernel/trace/trace_events_user.c
> index 67a92fe04ee4..9859e62b9838 100644
> --- a/kernel/trace/trace_events_user.c
> +++ b/kernel/trace/trace_events_user.c
> @@ -39,6 +39,7 @@
>  #define MAX_EVENT_DESC 512
>  #define EVENT_NAME(user_event) ((user_event)->tracepoint.name)
>  #define MAX_FIELD_ARRAY_SIZE 1024
> +#define MAX_FIELD_ARG_NAME 256
>  
>  static char *register_page_data;
>  
> @@ -694,13 +695,87 @@ static int user_event_free(struct dyn_event *ev)
>  	return destroy_user_event(user);
>  }
>  
> +static bool user_field_match(struct ftrace_event_field *field, int argc,
> +			     const char **argv, int *iout)
> +{
> +	char *field_name, *arg_name;
> +	int len, pos, i = *iout;
> +	bool colon = false, match = false;
> +
> +	if (i >= argc)
> +		return false;
> +
> +	len = MAX_FIELD_ARG_NAME;
> +	field_name = kmalloc(len, GFP_KERNEL);
> +	arg_name = kmalloc(len, GFP_KERNEL);
> +
> +	if (!arg_name || !field_name)
> +		goto out;
> +
> +	pos = 0;
> +
> +	for (; i < argc; ++i) {
> +		if (i != *iout)
> +			pos += snprintf(arg_name + pos, len - pos, " ");
> +
> +		pos += snprintf(arg_name + pos, len - pos, argv[i]);
> +
> +		if (strchr(argv[i], ';')) {
> +			++i;
> +			colon = true;
> +			break;
> +		}
> +	}
> +
> +	pos = 0;
> +
> +	pos += snprintf(field_name + pos, len - pos, field->type);
> +	pos += snprintf(field_name + pos, len - pos, " ");
> +	pos += snprintf(field_name + pos, len - pos, field->name);
> +
> +	if (colon)
> +		pos += snprintf(field_name + pos, len - pos, ";");
> +
> +	*iout = i;
> +
> +	match = strcmp(arg_name, field_name) == 0;
> +out:
> +	kfree(arg_name);
> +	kfree(field_name);
> +
> +	return match;
> +}
> +
> +static bool user_fields_match(struct user_event *user, int argc,
> +			      const char **argv)
> +{
> +	struct ftrace_event_field *field, *next;
> +	struct list_head *head = &user->fields;
> +	int i = 0;
> +
> +	list_for_each_entry_safe_reverse(field, next, head, link)
> +		if (!user_field_match(field, argc, argv, &i))
> +			return false;
> +
> +	if (i != argc)
> +		return false;
> +
> +	return true;
> +}
> +
>  static bool user_event_match(const char *system, const char *event,
>  			     int argc, const char **argv, struct dyn_event *ev)
>  {
>  	struct user_event *user = container_of(ev, struct user_event, devent);
> +	bool match;
>  
> -	return strcmp(EVENT_NAME(user), event) == 0 &&
> +	match = strcmp(EVENT_NAME(user), event) == 0 &&
>  		(!system || strcmp(system, USER_EVENTS_SYSTEM) == 0);
> +
> +	if (match && argc > 0)
> +		match = user_fields_match(user, argc, argv);
> +
> +	return match;
>  }
>  
>  static struct dyn_event_operations user_event_dops = {
> -- 
> 2.17.1
> 


-- 
Masami Hiramatsu <mhiramat@...nel.org>