kbuild: introduce __init_refok/__initdata_refok to supress section mismatch warnings

Throughout the kernel there are a few legitimite references
to init or exit sections. Most of these are covered by the
patterns included in modpost but a few nees special attention.
To avoid hardcoding a lot of function names in modpost introduce
a marker so relevant function/data can be marked.
When modpost see a reference to a init/exit function from
a function/data marked no warning will be issued.

Idea from: Andrew Morton <akpm@linux-foundation.org>

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 11 insertions, 0 deletions

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 2909391a8035..7c87267b6ff0 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -583,6 +583,12 @@ static int strrcmp(const char *s, const char *sub)
 
 /**
  * Whitelist to allow certain references to pass with no warning.
+ *
+ * Pattern 0:
+ *   Do not warn if funtion/data are marked with __init_refok/__initdata_refok.
+ *   The pattern is identified by:
+ *   fromsec = .text.init.refok | .data.init.refok
+ *
  * Pattern 1:
  *   If a module parameter is declared __initdata and permissions=0
  *   then this is legal despite the warning generated.
@@ -686,6 +692,11 @@ static int secref_whitelist(const char *modname, const char *tosec,
                 NULL
         };
 
+        /* Check for pattern 0 */
+        if ((strcmp(fromsec, ".text.init.refok") == 0) ||
+            (strcmp(fromsec, ".data.init.refok") == 0))
+                return 1;
+
         /* Check for pattern 1 */
         if (strcmp(tosec, ".init.data") != 0)
                 f1 = 0;