[PATCH v2] drm/xe: switch to local __basename() helper

[Carlos Llamas <cmllamas@google.com>]

Commit b0a2ee5567ab ("drm/xe: prepare xe_gen_wa_oob to be multi-use")
introduced a call to basename(). The GNU version of this function is not
portable and fails to build with alternative libc implementations like
musl or bionic. This causes the following build error:

  drivers/gpu/drm/xe/xe_gen_wa_oob.c:130:12: error: assignment to ‘const char *’ from ‘int’ makes pointer from integer without a cast [-Wint-conversion]
    130 |         fn = basename(fn);
        |            ^

While a POSIX version of basename() could be used, it would require a
separate header plus the behavior differs from GNU version in that it
might modify its argument. Not great.

Instead, implement a local __basename() helper based on strrchr() that
provides the same functionality and avoids portability issues.

Fixes: b0a2ee5567ab ("drm/xe: prepare xe_gen_wa_oob to be multi-use")
Suggested-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Tiffany Yang <ynaffit@google.com>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
---
v2:
 - Wrap changes in a helper function per Luca's feedback.
 - Fix typo in commit log: s/avoid/avoids/ per Tiffany.
 - Update commit log.
 - Collect tags.

v1:
https://lore.kernel.org/all/20250820201612.2549797-1-cmllamas@google.com/

 drivers/gpu/drm/xe/xe_gen_wa_oob.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/xe/xe_gen_wa_oob.c b/drivers/gpu/drm/xe/xe_gen_wa_oob.c
index 6581cb0f0e59..c18faccdeb90 100644
--- a/drivers/gpu/drm/xe/xe_gen_wa_oob.c
+++ b/drivers/gpu/drm/xe/xe_gen_wa_oob.c
@@ -123,11 +123,19 @@ static int parse(FILE *input, FILE *csource, FILE *cheader, char *prefix)
 	return 0;
 }
 
+/* Avoid GNU vs POSIX basename() discrepancy, just use our own */
+static const char *__basename(const char *s)
+{
+	const char *p = strrchr(s, '/');
+
+	return p ? p + 1 : s;
+}
+
 static int fn_to_prefix(const char *fn, char *prefix, size_t size)
 {
 	size_t len;
 
-	fn = basename(fn);
+	fn = __basename(fn);
 	len = strlen(fn);
 
 	if (len > size - 1)
-- 
2.51.0.rc2.233.g662b1ed5c5-goog