Module Name:    src
Committed By:   riastradh
Date:           Sun Dec 19 01:21:23 UTC 2021

Modified Files:
        src/sys/external/bsd/drm2/include/linux: mutex.h

Log Message:
recursive locking is bad, do not use this ever.


To generate a diff of this commit:
cvs rdiff -u -r1.15 -r1.16 src/sys/external/bsd/drm2/include/linux/mutex.h

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.

Modified files:

Index: src/sys/external/bsd/drm2/include/linux/mutex.h
diff -u src/sys/external/bsd/drm2/include/linux/mutex.h:1.15 src/sys/external/bsd/drm2/include/linux/mutex.h:1.16
--- src/sys/external/bsd/drm2/include/linux/mutex.h:1.15	Sun Dec 19 00:54:46 2021
+++ src/sys/external/bsd/drm2/include/linux/mutex.h	Sun Dec 19 01:21:22 2021
@@ -1,4 +1,4 @@
-/*	$NetBSD: mutex.h,v 1.15 2021/12/19 00:54:46 riastradh Exp $	*/
+/*	$NetBSD: mutex.h,v 1.16 2021/12/19 01:21:22 riastradh Exp $	*/
 
 /*-
  * Copyright (c) 2013 The NetBSD Foundation, Inc.
@@ -115,4 +115,23 @@ mutex_lock_nested(struct mutex *mutex, u
 	mutex_lock(mutex);
 }
 
+/*
+ * `recursive locking is bad, do not use this ever.'
+ * -- linux/scripts/checkpath.pl
+ */
+static inline enum {
+	MUTEX_TRYLOCK_FAILED,
+	MUTEX_TRYLOCK_SUCCESS,
+	MUTEX_TRYLOCK_RECURSIVE,
+}
+mutex_trylock_recursive(struct mutex *mutex)
+{
+	if (mutex_owned(&mutex->mtx_lock))
+		return MUTEX_TRYLOCK_RECURSIVE;
+	else if (mutex_tryenter(&mutex->mtx_lock))
+		return MUTEX_TRYLOCK_SUCCESS;
+	else
+		return MUTEX_TRYLOCK_FAILED;
+}
+
 #endif  /* _LINUX_MUTEX_H_ */

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