LU-8130 libcfs: port working hash from upstream

[fs/lustre-release.git] / libcfs / autoconf / lustre-libcfs.m4

diff --git a/libcfs/autoconf/lustre-libcfs.m4 b/libcfs/autoconf/lustre-libcfs.m4
index d437331..2763748 100644 (file)
--- a/libcfs/autoconf/lustre-libcfs.m4
+++ b/libcfs/autoconf/lustre-libcfs.m4
@@ -712,6 +712,22 @@ LB_CHECK_EXPORT([kset_find_obj], [lib/kobject.c],
 ]) # LIBCFS_EXPORT_KSET_FIND_OBJ
 
 #
+# Kernel version 4.6+ commit ef703f49a6c5b909a85149bb6625c4ed0d697186
+# fixed the brokenness of hash_64(). The fix removed GOLDEN_RATIO_PRIME_64
+# since it was a poor prime value.
+#
+AC_DEFUN([LIBCFS_BROKEN_HASH_64], [
+LB_CHECK_COMPILE([kernel has fixed hash_64()],
+broken_hash_64, [
+       #include <linux/hash.h>
+],[
+       int tmp = GOLDEN_RATIO_PRIME_64;
+],[
+       AC_DEFINE(HAVE_BROKEN_HASH_64, 1, [kernel hash_64() is broken])
+])
+]) # LIBCFS_BROKEN_HASH_64
+
+#
 # LIBCFS_STACKTRACE_OPS_ADDRESS_RETURN_INT
 #
 # linux 4.6 kernel changed stacktrace_ops address to return an int
@@ -995,6 +1011,7 @@ LIBCFS_KSTRTOBOOL_FROM_USER
 LIBCFS_CRYPTO_HASH_HELPERS
 LIBCFS_EXPORT_KSET_FIND_OBJ
 # 4.6
+LIBCFS_BROKEN_HASH_64
 LIBCFS_STACKTRACE_OPS_ADDRESS_RETURN_INT
 LIBCFS_GET_USER_PAGES_6ARG
 LIBCFS_STRINGHASH