Re: [PATCH i-g-t 02/10] lib/xe: Use stricter line-equality check when checking for workarounds

On Tue, Jul 21, 2026 at 03:59:55PM -0300, Gustavo Sousa wrote:
> Currently debugfs_file_has_wa() uses strstr() to check if a workaround
> name is present in the debugfs dump.  Using strstr() would match the
> workaround name anywhere in the dump buffer and with that we risk
> producing unexpected results if the checked workaround name happens to
> be a substring of another workaround present in the dump.
> 
> Fix that by making sure we match the workaround name with the full
> line from the dump.

There are other parts of IGT that use regular expressions from either
POSIX (regcomp / regexec) or Glib (g_regex_new / g_regex_match).  Would
it be possible to use one of those here instead of opencoding a match
function?


Matt

> 
> Signed-off-by: Gustavo Sousa <[email protected]>
> ---
>  lib/xe/xe_wa.c | 39 ++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 38 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/xe/xe_wa.c b/lib/xe/xe_wa.c
> index ff5daf529831..d44431e7e61f 100644
> --- a/lib/xe/xe_wa.c
> +++ b/lib/xe/xe_wa.c
> @@ -13,6 +13,43 @@
>  #include "xe/xe_wa.h"
>  #include "xe/xe_query.h"
>  
> +static bool debugfs_dump_has_wa(char *dump, const char *wa)
> +{
> +	char *a = dump;
> +
> +	while (*a) {
> +		const char *b = wa;
> +
> +		/*
> +		 * Each workaround name is indented by one tab
> +		 * character; unindented lines are used as "section
> +		 * names" identifying the type of workarounds that
> +		 * follow (e.g. "GT Workarounds", "Engine Workarounds"
> +		 * etc).
> +		 */
> +		if (*a++ != '\t')
> +			goto next_line;
> +
> +		while (*a == *b && !(*a == '\0' || *a == '\n' || *b == '\0')) {
> +			a++;
> +			b++;
> +		}
> +
> +		if ((*a == '\0' || *a == '\n') && *b == '\0')
> +			return true;
> +
> +	next_line:
> +		/* No match for this line, advance to the next one. */
> +		while (*a != '\n' && *a != '\0')
> +			a++;
> +
> +		if (*a == '\n')
> +			a++;
> +	}
> +
> +	return false;
> +}
> +
>  static int debugfs_file_has_wa(int drm_fd, int debugfs_fd,
>  			       const char *debugfs_name, const char *wa)
>  {
> @@ -23,7 +60,7 @@ static int debugfs_file_has_wa(int drm_fd, int debugfs_fd,
>  
>  	debugfs_dump = igt_sysfs_get(debugfs_fd, debugfs_name);
>  	if (debugfs_dump) {
> -		char *has_wa = strstr(debugfs_dump, wa);
> +		bool has_wa = debugfs_dump_has_wa(debugfs_dump, wa);
>  
>  		free(debugfs_dump);
>  
> 
> -- 
> 2.55.0
> 

-- 
Matt Roper
Graphics Software Engineer
Linux GPU Platform Enablement
Intel Corporation