From 451323135e56bc52945da72e2bf9f6b0992e35b3 Mon Sep 17 00:00:00 2001
From: dlg <>
Date: Mon, 4 Aug 2025 01:44:33 +0000
Subject: replace the flockfile backend with a per FILE recursive mutex.

the flockfile implementation in thread/rthread_file.c used an
external lock, and associated it with the relevant FILE * as needed.
this isn't great for a lot of reasons, complexity being the big
one, but the straw that broke the camels back is that it uses a
single spinlock to coordinate all of this, which in turn generates
a lot of sched_yield syscalls.

this avoids all the code complexity and the spinlock by just embedding
a small __rctmx in every FILE.

tested by and ok tb@ jca@
ok claudio@
---
 src/lib/libc/include/thread_private.h | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

(limited to 'src')

diff --git a/src/lib/libc/include/thread_private.h b/src/lib/libc/include/thread_private.h
index 7e7c716e2a..3e1dbcdf6e 100644
--- a/src/lib/libc/include/thread_private.h
+++ b/src/lib/libc/include/thread_private.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: thread_private.h,v 1.39 2025/07/16 16:22:58 deraadt Exp $ */
+/* $OpenBSD: thread_private.h,v 1.40 2025/08/04 01:44:33 dlg Exp $ */
 
 /* PUBLIC DOMAIN: No Rights Reserved. Marco S Hyman <marc@snafu.org> */
 
@@ -383,6 +383,12 @@ struct __rcmtx {
 	unsigned int		depth;
 };
 
+#define __RCMTX_INITIALIZER() {						\
+	.owner = NULL,							\
+	.mtx = __CMTX_INITIALIZER(),					\
+	.depth = 0,							\
+}
+
 struct pthread_mutex_attr {
 	int ma_type;
 	int ma_protocol;
-- 
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