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authorriastradh <riastradh@NetBSD.org>2021-12-19 11:21:20 +0000
committerriastradh <riastradh@NetBSD.org>2021-12-19 11:21:20 +0000
commitf3abf539cd19e029ce59cd31de8baaa699b9fcca (patch)
tree4978c2a98867958698f5df28632cebbd88fb4af3
parent6851f4c2e8133d8067c384907c8d94dc011745ee (diff)
linux/ww_mutex: Disable locking-against-self asserts in trylock.
This seems to be done intentionally in Linux.
-rw-r--r--sys/external/bsd/drm2/linux/linux_ww_mutex.c19
1 files changed, 17 insertions, 2 deletions
diff --git a/sys/external/bsd/drm2/linux/linux_ww_mutex.c b/sys/external/bsd/drm2/linux/linux_ww_mutex.c
index 79f248effc7..3d3d903ecc7 100644
--- a/sys/external/bsd/drm2/linux/linux_ww_mutex.c
+++ b/sys/external/bsd/drm2/linux/linux_ww_mutex.c
@@ -1,4 +1,4 @@
-/* $NetBSD: linux_ww_mutex.c,v 1.8 2021/12/19 10:38:14 riastradh Exp $ */
+/* $NetBSD: linux_ww_mutex.c,v 1.9 2021/12/19 11:21:20 riastradh Exp $ */
/*-
* Copyright (c) 2014 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: linux_ww_mutex.c,v 1.8 2021/12/19 10:38:14 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: linux_ww_mutex.c,v 1.9 2021/12/19 11:21:20 riastradh Exp $");
#include <sys/types.h>
#include <sys/atomic.h>
@@ -760,12 +760,27 @@ ww_mutex_trylock(struct ww_mutex *mutex)
WW_LOCKED(mutex);
ret = 1;
} else {
+ /*
+ * It is tempting to assert that we do not hold the
+ * mutex here, because trylock when we hold the lock
+ * already generally indicates a bug in the design of
+ * the code. However, it seems that Linux relies on
+ * this deep in ttm buffer reservation logic, so these
+ * assertions are disabled until we find another way to
+ * work around that or fix the bug that leads to it.
+ *
+ * That said: we should not be in the WW_WANTOWN state,
+ * which happens only while we're in the ww mutex logic
+ * waiting to acquire the lock.
+ */
+#if 0
KASSERTMSG(((mutex->wwm_state != WW_OWNED) ||
(mutex->wwm_u.owner != curlwp)),
"locking %p against myself: %p", mutex, curlwp);
KASSERTMSG(((mutex->wwm_state != WW_CTX) ||
(mutex->wwm_u.ctx->wwx_owner != curlwp)),
"locking %p against myself: %p", mutex, curlwp);
+#endif
KASSERTMSG(((mutex->wwm_state != WW_WANTOWN) ||
(mutex->wwm_u.ctx->wwx_owner != curlwp)),
"locking %p against myself: %p", mutex, curlwp);