Linux: Remove ZFS_AC_KERNEL_SRC_MODULE_PARAM_CALL_CONST autotools check

On older kernels, the definition for `module_param_call()` typecasts
function pointers to `(void *)`, which triggers -Werror, causing the
check to return false when it should return true.

Fixing this breaks the build process on some older kernels because they
define a `__check_old_set_param()` function in their headers that checks
for a non-constified `->set()`. We workaround that through the c
preprocessor by defining `__check_old_set_param(set)` to `(set)`, which
prevents the build failures.

However, it is now apparent that all kernels that we support have
adopted the GRSecurity change, so there is no need to have an explicit
autotools check for it anymore. We therefore remove the autotools check,
while adding the workaround to our headers for the build time
non-constified `->set()` check done by older kernel headers.

Reviewed-by: Brian Behlendorf <[email protected]>
Reviewed-by: Jorgen Lundman <[email protected]>
Reviewed-by: Ryan Moeller <[email protected]>
Reviewed-by: Alexander Motin <[email protected]>
Signed-off-by: Richard Yao <[email protected]>
Closes #13984
Closes #14004

1 files changed, 0 insertions, 33 deletions

diff --git a/config/kernel-mod-param.m4 b/config/kernel-mod-param.m4
deleted file mode 100644
index e00f19d61..000000000
--- a/config/kernel-mod-param.m4
+++ /dev/null
@@ -1,33 +0,0 @@
-dnl #
-dnl # Grsecurity kernel API change
-dnl # constified parameters of module_param_call() methods
-dnl #
-AC_DEFUN([ZFS_AC_KERNEL_SRC_MODULE_PARAM_CALL_CONST], [
-	ZFS_LINUX_TEST_SRC([module_param_call], [
-		#include <linux/module.h>
-		#include <linux/moduleparam.h>
-
-		int param_get(char *b, const struct kernel_param *kp)
-		{
-			return (0);
-		}
-
-		int param_set(const char *b, const struct kernel_param *kp)
-		{
-			return (0);
-		}
-
-		module_param_call(p, param_set, param_get, NULL, 0644);
-	],[])
-])
-
-AC_DEFUN([ZFS_AC_KERNEL_MODULE_PARAM_CALL_CONST], [
-	AC_MSG_CHECKING([whether module_param_call() is hardened])
-	ZFS_LINUX_TEST_RESULT([module_param_call], [
-		AC_MSG_RESULT(yes)
-		AC_DEFINE(MODULE_PARAM_CALL_CONST, 1,
-		    [hardened module_param_call])
-	],[
-		AC_MSG_RESULT(no)
-	])
-])