linux-kernel - Re: [PATCH] dynamic_debug: add wildcard support to filter files/functions/modules

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Message-ID: <1374770840.1957.4.camel@joe-AO722>
Date:	Thu, 25 Jul 2013 09:47:20 -0700
From:	Joe Perches <joe@...ches.com>
To:	"Du, Changbin" <changbin.du@...il.com>
Cc:	jbaron@...hat.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] dynamic_debug: add wildcard support to filter
 files/functions/modules

On Thu, 2013-07-25 at 21:02 +0800, Du, Changbin wrote:
> From: "Du, Changbin" <changbin.du@...il.com>
> 
> This patch add wildcard '*'(matches zero or more characters) and '?'
> (matches one character) support when qurying debug flags.

Seems very useful.  Caveat below.

> diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
[]
> @@ -127,6 +127,21 @@ static void vpr_info_dq(const struct ddebug_query *query, const char *msg)
>  		 query->first_lineno, query->last_lineno);
>  }
>  
> +static int match_pattern(char *pat, char *str)
> +{
> +	switch (*pat) {
> +	case '\0':
> +		return !*str;
> +	case '*':
> +		return  match_pattern(pat+1, str) || 
> +			(*str && match_pattern(pat, str+1));
> +	case '?':
> +		return *str && match_pattern(pat+1, str+1);
> +	default:
> +		return *pat == *str && match_pattern(pat+1, str 1);
> +	}
> +}

What's the maximum length string used today?
On a very long pattern, can this recursion cause stack overflow?

Other than that, I like it.


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