From 6c9433c150ad12d01f7ea4cfc72c8647a08ac5fc Mon Sep 17 00:00:00 2001
From: Brian Behlendorf <behlendorf1@llnl.gov>
Date: Wed, 20 May 2009 10:56:13 -0700
Subject: [PATCH] SLES10 Fixes (part 3): - Configure check for
 mutex_lock_nested().  This function was introduced   as part of the mutex
 validator in 2.6.18, but if it's unavailable then   it's safe to fallback to
 a plain mutex_lock().

---
 config/spl-build.m4          | 23 +++++++++++++
 configure                    | 67 ++++++++++++++++++++++++++++++++++++
 configure.ac                 |  1 +
 include/linux/mutex_compat.h | 12 +++++++
 include/sys/types.h          |  1 +
 spl_config.h.in              |  3 ++
 6 files changed, 107 insertions(+)
 create mode 100644 include/linux/mutex_compat.h

diff --git a/config/spl-build.m4 b/config/spl-build.m4
index ebc2721..0f84995 100644
--- a/config/spl-build.m4
+++ b/config/spl-build.m4
@@ -705,6 +705,29 @@ AC_DEFUN([SPL_AC_INODE_I_MUTEX], [
 	])
 ])
 
+dnl #
+dnl # 2.6.18 API change,
+dnl # First introduced 'mutex_lock_nested()' in include/linux/mutex.h,
+dnl # as part of the mutex validator.  Fallback to using 'mutex_lock()' 
+dnl # if the mutex validator is disabled or otherwise unavailable.
+dnl #
+AC_DEFUN([SPL_AC_MUTEX_LOCK_NESTED], [
+	AC_MSG_CHECKING([whether mutex_lock_nested() is available])
+	SPL_LINUX_TRY_COMPILE([
+		#include <linux/mutex.h>
+	],[
+		struct mutex mutex;
+		mutex_init(&mutex);
+		mutex_lock_nested(&mutex, 0);
+	],[
+		AC_MSG_RESULT(yes)
+		AC_DEFINE(HAVE_MUTEX_LOCK_NESTED, 1,
+		[mutex_lock_nested() is available])
+	],[
+		AC_MSG_RESULT(no)
+	])
+])
+
 dnl #
 dnl # 2.6.22 API change,
 dnl # First introduced 'div64_64()' in lib/div64.c
diff --git a/configure b/configure
index 96d9d88..c16397c 100755
--- a/configure
+++ b/configure
@@ -20510,6 +20510,73 @@ fi
 
 
 
+	echo "$as_me:$LINENO: checking whether mutex_lock_nested() is available" >&5
+echo $ECHO_N "checking whether mutex_lock_nested() is available... $ECHO_C" >&6
+
+
+cat >conftest.c <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+
+		#include <linux/mutex.h>
+
+int
+main (void)
+{
+
+		struct mutex mutex;
+		mutex_init(&mutex);
+		mutex_lock_nested(&mutex, 0);
+
+  ;
+  return 0;
+}
+
+_ACEOF
+
+
+	rm -Rf build && mkdir -p build
+	echo "obj-m := conftest.o" >build/Makefile
+	if { ac_try='cp conftest.c build && make modules LINUXINCLUDE="-Iinclude -Iinclude2 -I$LINUX/include -include include/linux/autoconf.h" -o tmp_include_depends -o scripts -o include/config/MARKER -C $LINUX_OBJ EXTRA_CFLAGS="-Werror-implicit-function-declaration $EXTRA_KCFLAGS" $ARCH_UM M=$PWD/build'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } >/dev/null && { ac_try='test -s build/conftest.o'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+
+		echo "$as_me:$LINENO: result: yes" >&5
+echo "${ECHO_T}yes" >&6
+
+cat >>confdefs.h <<\_ACEOF
+#define HAVE_MUTEX_LOCK_NESTED 1
+_ACEOF
+
+
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+		echo "$as_me:$LINENO: result: no" >&5
+echo "${ECHO_T}no" >&6
+
+
+
+fi
+
+	rm -Rf build
+
+
+
+
 	echo "$as_me:$LINENO: checking whether symbol div64_64 is exported" >&5
 echo $ECHO_N "checking whether symbol div64_64 is exported... $ECHO_C" >&6
 	grep -q -E '[[:space:]]div64_64[[:space:]]' $LINUX_OBJ/Module.symvers 2>/dev/null
diff --git a/configure.ac b/configure.ac
index 179dbc1..e056297 100644
--- a/configure.ac
+++ b/configure.ac
@@ -67,6 +67,7 @@ SPL_AC_UACCESS_HEADER
 SPL_AC_KMALLOC_NODE
 SPL_AC_MONOTONIC_CLOCK
 SPL_AC_INODE_I_MUTEX
+SPL_AC_MUTEX_LOCK_NESTED
 SPL_AC_DIV64_64
 SPL_AC_DIV64_U64
 SPL_AC_3ARGS_ON_EACH_CPU
diff --git a/include/linux/mutex_compat.h b/include/linux/mutex_compat.h
new file mode 100644
index 0000000..4907240
--- /dev/null
+++ b/include/linux/mutex_compat.h
@@ -0,0 +1,12 @@
+#ifndef _SPL_MUTEX_COMPAT_H
+#define _SPL_MUTEX_COMPAT_H
+
+#include <linux/mutex.h>
+
+/* mutex_lock_nested() introduced in 2.6.18 */
+#ifndef HAVE_MUTEX_LOCK_NESTED
+# define mutex_lock_nested(lock, subclass)	mutex_lock(lock)
+#endif /* HAVE_MUTEX_LOCK_NESTED */
+
+#endif /* _SPL_MUTEX_COMPAT_H */
+
diff --git a/include/sys/types.h b/include/sys/types.h
index 5fd3a93..252def7 100644
--- a/include/sys/types.h
+++ b/include/sys/types.h
@@ -17,6 +17,7 @@ extern "C" {
 #include <linux/smp_compat.h>
 #include <linux/workqueue_compat.h>
 #include <linux/kallsyms_compat.h>
+#include <linux/mutex_compat.h>
 
 #ifndef HAVE_UINTPTR_T
 typedef unsigned long			uintptr_t;
diff --git a/spl_config.h.in b/spl_config.h.in
index 4369f85..e3b80e8 100644
--- a/spl_config.h.in
+++ b/spl_config.h.in
@@ -87,6 +87,9 @@
 /* monotonic_clock() is available */
 #undef HAVE_MONOTONIC_CLOCK
 
+/* mutex_lock_nested() is available */
+#undef HAVE_MUTEX_LOCK_NESTED
+
 /* next_online_pgdat() is available */
 #undef HAVE_NEXT_ONLINE_PGDAT
 
-- 
2.39.2