Revert "Linux 6.5 compat: register_sysctl_table removed"

This reverts commit b35374f as there
are error messages when loading the SPL module. Errors seemed to be tied
to duplicate a duplicate entry.

Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Brian Atkinson <[email protected]>
Closes #15134

Author: bwatkinson

config/kernel-register_sysctl_table.m4

@@ -160,7 +160,6 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_SRC], [
 	ZFS_AC_KERNEL_SRC_FILEMAP
 	ZFS_AC_KERNEL_SRC_WRITEPAGE_T
 	ZFS_AC_KERNEL_SRC_RECLAIMED
-	ZFS_AC_KERNEL_SRC_REGISTER_SYSCTL_TABLE
 	case "$host_cpu" in
 		powerpc*)
 			ZFS_AC_KERNEL_SRC_CPU_HAS_FEATURE
@@ -300,7 +299,6 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_RESULT], [
 	ZFS_AC_KERNEL_FILEMAP
 	ZFS_AC_KERNEL_WRITEPAGE_T
 	ZFS_AC_KERNEL_RECLAIMED
-	ZFS_AC_KERNEL_REGISTER_SYSCTL_TABLE
 	case "$host_cpu" in
 		powerpc*)
 			ZFS_AC_KERNEL_CPU_HAS_FEATURE

config/kernel.m4

@@ -624,7 +624,6 @@ static struct ctl_table spl_table[] = {
 		.mode		= 0644,
 		.proc_handler	= &proc_dohostid,
 	},
-#ifdef HAVE_REGISTER_SYSCTL_TABLE
 	{
 		.procname	= "kmem",
 		.mode		= 0555,
@@ -635,11 +634,9 @@ static struct ctl_table spl_table[] = {
 		.mode		= 0555,
 		.child		= spl_kstat_table,
 	},
-#endif
 	{},
 };
 
-#ifdef HAVE_REGISTER_SYSCTL_TABLE
 static struct ctl_table spl_dir[] = {
 	{
 		.procname	= "spl",
@@ -651,38 +648,21 @@ static struct ctl_table spl_dir[] = {
 
 static struct ctl_table spl_root[] = {
 	{
-		.procname	= "kernel",
-		.mode		= 0555,
-		.child		= spl_dir,
+	.procname = "kernel",
+	.mode = 0555,
+	.child = spl_dir,
 	},
 	{}
 };
-#endif
 
 int
 spl_proc_init(void)
 {
 	int rc = 0;
 
-#ifdef HAVE_REGISTER_SYSCTL_TABLE
 	spl_header = register_sysctl_table(spl_root);
 	if (spl_header == NULL)
 		return (-EUNATCH);
-#else
-	spl_header = register_sysctl("kernel/spl", spl_table);
-	if (spl_header == NULL)
-		return (-EUNATCH);
-
-	if (register_sysctl("kernel/spl/kmem", spl_kmem_table) == NULL) {
-		rc = -EUNATCH;
-		goto out;
-	}
-
-	if (register_sysctl("kernel/spl/kstat", spl_kstat_table) == NULL) {
-		rc = -EUNATCH;
-		goto out;
-	}
-#endif
 
 	proc_spl = proc_mkdir("spl", NULL);
 	if (proc_spl == NULL) {