From e30fcbe3822ab740cef6ff2584dd0a1429ab10a5 Mon Sep 17 00:00:00 2001
From: Ian Moffett <ian@osmora.org>
Date: Thu, 17 Apr 2025 02:58:20 -0400
Subject: kernel: synch: Add system-wide locking

Add system-wide locking for critical code sections.

Signed-off-by: Ian Moffett <ian@osmora.org>
---
 sys/kern/kern_synch.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

(limited to 'sys/kern/kern_synch.c')

diff --git a/sys/kern/kern_synch.c b/sys/kern/kern_synch.c
index 2b64673..57b27d0 100644
--- a/sys/kern/kern_synch.c
+++ b/sys/kern/kern_synch.c
@@ -38,6 +38,9 @@
 #define pr_trace(fmt, ...) kprintf("synch: " fmt, ##__VA_ARGS__)
 #define pr_error(...) pr_trace(__VA_ARGS__)
 
+/* XXX: Be very careful with this */
+static struct spinlock __syslock;
+
 /*
  * Returns 0 on success, returns non-zero value
  * on timeout/failure.
@@ -110,3 +113,26 @@ spinlock_release(struct spinlock *lock)
 {
     __atomic_clear(&lock->lock, __ATOMIC_RELEASE);
 }
+
+/*
+ * Attempt to hold the system-wide lock, returns 1
+ * if already held.
+ *
+ * XXX: Only use for CRITICAL code sections.
+ */
+int
+syslock(void)
+{
+    return spinlock_try_acquire(&__syslock);
+}
+
+/*
+ * Release the system-wide lock
+ *
+ * XXX: Only use for CRITICAL code sections.
+ */
+void
+sysrel(void)
+{
+    spinlock_release(&__syslock);
+}
-- 
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