drm: make drm_get_format_name thread-safe

Signed-off-by: Eric Engestrom <eric@engestrom.ch>
[danvet: Clarify that the returned pointer must be freed with
kfree().]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 9 insertions, 8 deletions

diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c
index 0645c85d5f95..d8f65c4fadf7 100644
--- a/drivers/gpu/drm/drm_fourcc.c
+++ b/drivers/gpu/drm/drm_fourcc.c
@@ -39,16 +39,14 @@ static char printable_char(int c)
  * drm_get_format_name - return a string for drm fourcc format
  * @format: format to compute name of
  *
- * Note that the buffer used by this function is globally shared and owned by
- * the function itself.
- *
- * FIXME: This isn't really multithreading safe.
+ * Note that the buffer returned by this function is owned by the caller
+ * and will need to be freed using kfree().
  */
 const char *drm_get_format_name(uint32_t format)
 {
-	static char buf[32];
+	char *buf = kmalloc(32, GFP_KERNEL);
 
-	snprintf(buf, sizeof(buf),
+	snprintf(buf, 32,
 		 "%c%c%c%c %s-endian (0x%08x)",
 		 printable_char(format & 0xff),
 		 printable_char((format >> 8) & 0xff),
@@ -73,6 +71,8 @@ EXPORT_SYMBOL(drm_get_format_name);
 void drm_fb_get_bpp_depth(uint32_t format, unsigned int *depth,
 			  int *bpp)
 {
+	const char *format_name;
+
 	switch (format) {
 	case DRM_FORMAT_C8:
 	case DRM_FORMAT_RGB332:
@@ -127,8 +127,9 @@ void drm_fb_get_bpp_depth(uint32_t format, unsigned int *depth,
 		*bpp = 32;
 		break;
 	default:
-		DRM_DEBUG_KMS("unsupported pixel format %s\n",
-			      drm_get_format_name(format));
+		format_name = drm_get_format_name(format);
+		DRM_DEBUG_KMS("unsupported pixel format %s\n", format_name);
+		kfree(format_name);
 		*depth = 0;
 		*bpp = 0;
 		break;