svn commit: r329955 - stable/11/sys/compat/linuxkpi/common/include/linux

[Hans Petter Selasky]

Author: hselasky
Date: Sun Feb 25 10:19:44 2018
New Revision: 329955
URL: https://svnweb.freebsd.org/changeset/base/329955

Log:
  MFC r329378:
  Implement mutex_trylock_recursive() in the LinuxKPI.
  
  Submitted by:	Johannes Lundberg <johalun0 at gmail.com>
  Sponsored by:	Mellanox Technologies

Modified:
  stable/11/sys/compat/linuxkpi/common/include/linux/mutex.h
Directory Properties:
  stable/11/   (props changed)

Modified: stable/11/sys/compat/linuxkpi/common/include/linux/mutex.h
==============================================================================
--- stable/11/sys/compat/linuxkpi/common/include/linux/mutex.h	Sun Feb 25 10:18:49 2018	(r329954)
+++ stable/11/sys/compat/linuxkpi/common/include/linux/mutex.h	Sun Feb 25 10:19:44 2018	(r329955)
@@ -77,6 +77,21 @@ typedef struct mutex {
 	!!sx_try_xlock(&(_m)->sx);		\
 })
 
+enum mutex_trylock_recursive_enum {
+	MUTEX_TRYLOCK_FAILED = 0,
+	MUTEX_TRYLOCK_SUCCESS = 1,
+	MUTEX_TRYLOCK_RECURSIVE = 2,
+};
+
+static inline __must_check enum mutex_trylock_recursive_enum
+mutex_trylock_recursive(struct mutex *lock)
+{
+	if (unlikely(sx_xholder(&lock->sx) == curthread))
+		return (MUTEX_TRYLOCK_RECURSIVE);
+
+	return (mutex_trylock(lock));
+}
+
 #define	mutex_init(_m) \
 	linux_mutex_init(_m, mutex_name(#_m), SX_NOWITNESS)