From e0928e6ddf94c25f026d02643ddd0a2016ddd17b Mon Sep 17 00:00:00 2001
From: Ian Moffett <ian@osmora.org>
Date: Sun, 15 Dec 2024 22:49:50 -0500
Subject: kernel: synch: Add spinlock with timeout

Signed-off-by: Ian Moffett <ian@osmora.org>
---
 sys/include/sys/systm.h |  3 ++
 sys/kern/kern_synch.c   | 73 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 76 insertions(+)
 create mode 100644 sys/kern/kern_synch.c

(limited to 'sys')

diff --git a/sys/include/sys/systm.h b/sys/include/sys/systm.h
index 1b17a06..2f870a6 100644
--- a/sys/include/sys/systm.h
+++ b/sys/include/sys/systm.h
@@ -31,10 +31,13 @@
 #define _SYS_SYSTM_H_
 
 #include <sys/types.h>
+#include <sys/spinlock.h>
 
 #if defined(_KERNEL)
 int copyin(const void *uaddr, void *kaddr, size_t len);
 int copyout(const void *kaddr, void *uaddr, size_t len);
+
 int copyinstr(const void *uaddr, char *kaddr, size_t len);
+int spinlock_usleep(struct spinlock *lock, size_t usec_max);
 #endif  /* _KERNEL */
 #endif  /* !_SYS_SYSTM_H_ */
diff --git a/sys/kern/kern_synch.c b/sys/kern/kern_synch.c
new file mode 100644
index 0000000..1b78642
--- /dev/null
+++ b/sys/kern/kern_synch.c
@@ -0,0 +1,73 @@
+/*
+ * Copyright (c) 2023-2024 Ian Marco Moffett and the Osmora Team.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of Hyra nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/types.h>
+#include <sys/systm.h>
+#include <sys/errno.h>
+#include <sys/syslog.h>
+#include <dev/timer.h>
+
+#define pr_trace(fmt, ...) kprintf("synch: " fmt, ##__VA_ARGS__)
+#define pr_error(...) pr_trace(__VA_ARGS__)
+
+/*
+ * Returns 0 on success, returns non-zero value
+ * on timeout/failure.
+ */
+int
+spinlock_usleep(struct spinlock *lock, size_t usec_max)
+{
+    struct timer tmr;
+    size_t usec_start, usec_cur;
+    size_t usec_elap;
+    int err;
+
+    if ((err = req_timer(TIMER_GP, &tmr)) != 0) {
+        pr_error("spinlock_usleep: req_timer() returned %d\n", err);
+        pr_error("spinlock_usleep: Failed to request timer...\n");
+        return err;
+    }
+
+    if (tmr.get_time_usec == NULL) {
+        pr_error("spinlock_usleep: Timer does not have get_time_usec()\n");
+        return -ENOTSUP;
+    }
+
+    usec_start = tmr.get_time_usec();
+    while (__atomic_test_and_set(&lock->lock, __ATOMIC_ACQUIRE)) {
+        usec_cur = tmr.get_time_usec();
+        usec_elap = (usec_cur - usec_start);
+
+        if (usec_elap > usec_max) {
+            return -1;
+        }
+    }
+
+    return 0;
+}
-- 
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