linux-kernel - Re: [PATCH 04/14] tools lib traceevent: Get rid of malloc_or_die() allocate

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Message-ID: <20131209110519.7e9fd95c@gandalf.local.home>
Date:	Mon, 9 Dec 2013 11:05:19 -0500
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Namhyung Kim <namhyung@...nel.org>
Cc:	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...nel.org>, Jiri Olsa <jolsa@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Namhyung Kim <namhyung.kim@....com>
Subject: Re: [PATCH 04/14] tools lib traceevent: Get rid of malloc_or_die()
 allocate_arg()

On Mon,  9 Dec 2013 14:34:01 +0900
Namhyung Kim <namhyung@...nel.org> wrote:

> @@ -409,8 +408,10 @@ create_arg_op(enum filter_op_type btype)
>  	struct filter_arg *arg;
>  
>  	arg = allocate_arg();
> -	arg->type = FILTER_ARG_OP;
> -	arg->op.type = btype;
> +	if (arg) {
> +		arg->type = FILTER_ARG_OP;
> +		arg->op.type = btype;
> +	}
>  
>  	return arg;
>  }
> @@ -421,8 +422,10 @@ create_arg_exp(enum filter_exp_type etype)
>  	struct filter_arg *arg;
>  
>  	arg = allocate_arg();
> -	arg->type = FILTER_ARG_EXP;
> -	arg->op.type = etype;
> +	if (arg) {
> +		arg->type = FILTER_ARG_EXP;
> +		arg->op.type = etype;
> +	}
>  
>  	return arg;
>  }
> @@ -433,9 +436,11 @@ create_arg_cmp(enum filter_exp_type etype)
>  	struct filter_arg *arg;
>  
>  	arg = allocate_arg();
> -	/* Use NUM and change if necessary */
> -	arg->type = FILTER_ARG_NUM;
> -	arg->op.type = etype;
> +	if (arg) {
> +		/* Use NUM and change if necessary */
> +		arg->type = FILTER_ARG_NUM;
> +		arg->op.type = etype;
> +	}
>  
>  	return arg;
>  }
> @@ -896,8 +901,10 @@ static struct filter_arg *collapse_tree(struct filter_arg *arg)
>  	case FILTER_VAL_FALSE:
>  		free_arg(arg);
>  		arg = allocate_arg();
> -		arg->type = FILTER_ARG_BOOLEAN;
> -		arg->boolean.value = ret == FILTER_VAL_TRUE;
> +		if (arg) {
> +			arg->type = FILTER_ARG_BOOLEAN;
> +			arg->boolean.value = ret == FILTER_VAL_TRUE;
> +		}

Just a nit, but I wonder if all these would look nicer if we just did:

	arg = allocate_arg();
	if (!arg)
		return NULL;
	[...]

Instead of doing the work within an if statement.

Also, I prefer if (!arg) over if (arg == NULL), but I'm not going to
fight over that ;-)

-- Steve

>  	}
>  
>  	return arg;
> @@ -1044,6 +1051,8 @@ process_filter(struct event_format *event, struct filter_arg **parg,
>  			switch (op_type) {
>  			case OP_BOOL:
>  				arg = create_arg_op(btype);
> +				if (arg == NULL)
> +					goto fail_alloc;
>  				if (current_op)
>  					ret = add_left(arg, current_op);
>  				else
> @@ -1054,6 +1063,8 @@ process_filter(struct event_format *event, struct filter_arg **parg,
>  
>  			case OP_NOT:
>  				arg = create_arg_op(btype);
> +				if (arg == NULL)
> +					goto fail_alloc;
>  				if (current_op)
>  					ret = add_right(current_op, arg, error_str);
>  				if (ret < 0)
> @@ -1073,6 +1084,8 @@ process_filter(struct event_format *event, struct filter_arg **parg,
>  					arg = create_arg_exp(etype);
>  				else
>  					arg = create_arg_cmp(ctype);
> +				if (arg == NULL)
> +					goto fail_alloc;
>  
>  				if (current_op)
>  					ret = add_right(current_op, arg, error_str);
> @@ -1106,11 +1119,16 @@ process_filter(struct event_format *event, struct filter_arg **parg,
>  		current_op = current_exp;
>  
>  	current_op = collapse_tree(current_op);
> +	if (current_op == NULL)
> +		goto fail_alloc;
>  
>  	*parg = current_op;
>  
>  	return 0;
>  
> + fail_alloc:
> +	show_error(error_str, "failed to allocate filter arg");
> +	goto fail;
>   fail_print:
>  	show_error(error_str, "Syntax error");
>   fail:
> @@ -1141,6 +1159,10 @@ process_event(struct event_format *event, const char *filter_str,
>  	/* If parg is NULL, then make it into FALSE */
>  	if (!*parg) {
>  		*parg = allocate_arg();
> +		if (*parg == NULL) {
> +			show_error(error_str, "failed to allocate filter arg");
> +			return -1;
> +		}
>  		(*parg)->type = FILTER_ARG_BOOLEAN;
>  		(*parg)->boolean.value = FILTER_FALSE;
>  	}
> @@ -1164,6 +1186,10 @@ static int filter_event(struct event_filter *filter,
>  	} else {
>  		/* just add a TRUE arg */
>  		arg = allocate_arg();
> +		if (arg == NULL) {
> +			show_error(error_str, "failed to allocate filter arg");
> +			return -1;
> +		}
>  		arg->type = FILTER_ARG_BOOLEAN;
>  		arg->boolean.value = FILTER_TRUE;
>  	}
> @@ -1399,6 +1425,9 @@ static int copy_filter_type(struct event_filter *filter,
>  	if (strcmp(str, "TRUE") == 0 || strcmp(str, "FALSE") == 0) {
>  		/* Add trivial event */
>  		arg = allocate_arg();
> +		if (arg == NULL)
> +			return -1;
> +
>  		arg->type = FILTER_ARG_BOOLEAN;
>  		if (strcmp(str, "TRUE") == 0)
>  			arg->boolean.value = 1;

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