[src/trunk]: src/sys/external/bsd/drm2/include/linux recursive locking is bad...

[riastradh <riastradh%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/c7dfb3f5240e
branches:  trunk
changeset: 1027956:c7dfb3f5240e
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Sun Dec 19 01:21:22 2021 +0000

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

diffstat:

 sys/external/bsd/drm2/include/linux/mutex.h |  21 ++++++++++++++++++++-
 1 files changed, 20 insertions(+), 1 deletions(-)

diffs (33 lines):

diff -r 06d36b045201 -r c7dfb3f5240e sys/external/bsd/drm2/include/linux/mutex.h
--- a/sys/external/bsd/drm2/include/linux/mutex.h       Sun Dec 19 01:21:15 2021 +0000
+++ b/sys/external/bsd/drm2/include/linux/mutex.h       Sun Dec 19 01:21:22 2021 +0000
@@ -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(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_ */