From 312902931f0d69d2519f8c9074a610cdc338f29b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Lo=C3=AFc=20Gr=C3=A9goire?= <loic@gregoire.dev>
Date: Sun, 2 Aug 2026 21:45:47 -0400
Subject: [PATCH] ps: fix stack freeing bug

The thread could still be running on its stack whenever the stack ends
up getting reaped, which would free and reuse the stack before it
stops being used. Lock and unlock the thread to wait until it finishes
switching.
---
 src/proc/thread.zig | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/proc/thread.zig b/src/proc/thread.zig
index 77d0a89..3dc9349 100644
--- a/src/proc/thread.zig
+++ b/src/proc/thread.zig
@@ -25,6 +25,11 @@ fn reap_thread(obj: *anyopaque, _: ?*anyopaque) void {
     // Bleh
     const entry: *rtl.List.Entry = @fieldParentPtr("next", link);
     const ketd: *ke.Thread = @fieldParentPtr("runq_link", entry);
+
+    // Wait until the thread finishes switching off its stack.
+    const ipl = ketd.lock.acquire();
+    ketd.lock.release(ipl);
+
     const td: *Thread = @fieldParentPtr("kern", ketd);
 
     psp.turnstile_zone.destroy(td.kern.turnstile);