From 015984a53e6b9b089566762ec00973d3aa126ae3 Mon Sep 17 00:00:00 2001
From: Ian Moffett <ian@osmora.org>
Date: Wed, 16 Jul 2025 19:33:13 -0400
Subject: kernel: proc: Decrement proc count on exit

Previously, our process counter was monotonic (wuh oh!). We want to be
sure that it decrements when a process exits.

- Rename nthreads to g_nthreads as a global
- Atomically increment on enter and decrement on exit

Signed-off-by: Ian Moffett <ian@osmora.org>
---
 sys/kern/kern_exit.c | 6 ++++++
 1 file changed, 6 insertions(+)

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

diff --git a/sys/kern/kern_exit.c b/sys/kern/kern_exit.c
index 2c9e2e4..6b41cbd 100644
--- a/sys/kern/kern_exit.c
+++ b/sys/kern/kern_exit.c
@@ -30,6 +30,7 @@
 #include <sys/proc.h>
 #include <sys/sched.h>
 #include <sys/syslog.h>
+#include <sys/atomic.h>
 #include <sys/panic.h>
 #include <sys/filedesc.h>
 #include <sys/vnode.h>
@@ -44,6 +45,8 @@
 #define pr_trace(fmt, ...) kprintf("exit: " fmt, ##__VA_ARGS__)
 #define pr_error(...) pr_trace(__VA_ARGS__)
 
+extern volatile size_t g_nthreads;
+
 static void
 unload_td(struct proc *td)
 {
@@ -150,6 +153,9 @@ exit1(struct proc *td, int flags)
     td->flags |= PROC_EXITING;
     parent = td->parent;
 
+    /* We have one less process in the system! */
+    atomic_dec_64(&g_nthreads);
+
     /* If we have any children, kill them too */
     if (td->nleaves > 0) {
         TAILQ_FOREACH(procp, &td->leafq, leaf_link) {
-- 
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