From 782196275b6a435bf9b64df77978c5c87caf2549 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Lo=C3=AFc=20Gr=C3=A9goire?= <loic@gregoire.dev>
Date: Sat, 18 Jul 2026 16:45:32 -0400
Subject: [PATCH] mm+ke: make shootdowns use HandoffList

---
 src/kern/init.zig      |  1 -
 src/kern/shootdown.zig | 10 +++-------
 src/mm/tlb.zig         | 28 +++++++++++++++++-----------
 3 files changed, 20 insertions(+), 19 deletions(-)

diff --git a/src/kern/init.zig b/src/kern/init.zig
index 0ff8d1f..772238a 100644
--- a/src/kern/init.zig
+++ b/src/kern/init.zig
@@ -19,7 +19,6 @@ pub fn init(boot_info: *r.BootInfo) linksection(r.init) void {
     ki.log.init();
     ki.cpu.init_cpu(0);
     ki.turnstile.init_turnstiles();
-    ki.shootdown.init();
 
     thread0.init(@intFromPtr(&stack), r.kib(16), ke.Thread.Priority.idle_low, ki.sched.idle, null);
     thread0.priority = 0;
diff --git a/src/kern/shootdown.zig b/src/kern/shootdown.zig
index bde9708..dc7efe1 100644
--- a/src/kern/shootdown.zig
+++ b/src/kern/shootdown.zig
@@ -14,7 +14,7 @@ pub const ShootdownState = struct {
     /// This is used as a counter when the request is outstanding,
     /// otherwise it is set to the `slot_*` values below.
     state: std.atomic.Value(u16),
-    link: rtl.List.Entry,
+    link: ?*anyopaque,
     /// Base virtual address of the shootdown.
     base: r.VAddr,
     /// Number of pages to flush.
@@ -42,7 +42,7 @@ const slot_free: u16 = std.math.maxInt(u16);
 const slot_reserved: u16 = std.math.maxInt(u16) - 1;
 const percpu = ke.CpuLocal(PerCpu, undefined);
 
-pub var shootdowns: ke.Queue = undefined;
+pub var shootdowns: rtl.HandoffList = undefined;
 
 var sync_counter: std.atomic.Value(usize) = .init(0);
 var sync_addr: r.VAddr = 0;
@@ -149,7 +149,7 @@ pub fn process_shootdowns() void {
                 flush_range(state.base, state.npages);
 
                 if (state.state.fetchSub(1, .release) == 1) {
-                    shootdowns.insert(&state.link, .Tail);
+                    shootdowns.insert(&state.link);
                 }
             }
         }
@@ -189,7 +189,3 @@ pub fn submit(state: ShootdownState, target_mask: ke.CpuMask) !void {
         percpu.remote(@truncate(bit)).senders.set(curcpu, .release);
     }
 }
-
-pub fn init() void {
-    shootdowns.init(ke.ncpus);
-}
diff --git a/src/mm/tlb.zig b/src/mm/tlb.zig
index 009a0d6..154cb9a 100644
--- a/src/mm/tlb.zig
+++ b/src/mm/tlb.zig
@@ -2,19 +2,26 @@
 
 const r = @import("root");
 const std = @import("std");
+const rtl = @import("rtl");
 
 const ke = r.ke;
 const mm = r.mm;
 const mi = mm.private;
 const ps = r.ps;
+const ex = r.ex;
 
 pub var sync_shootdowns: std.atomic.Value(usize) = .init(0);
 pub var async_shootdowns: std.atomic.Value(usize) = .init(0);
 pub var sent_shootdowns: std.atomic.Value(usize) = .init(0);
 
+var work_item: ex.WorkItem = undefined;
+
 /// Reclaim the memory associated with a state.
 /// This can only be done when all CPUs have flushed their TLB.
-fn reclaim_state(state: *ke.ShootdownState) void {
+fn reclaim_state(obj: *anyopaque, _: ?*anyopaque) void {
+    const link: *?*anyopaque = @ptrCast(@alignCast(obj));
+    const state: *ke.ShootdownState = @fieldParentPtr("link", link);
+
     const space: *mm.Space = @ptrFromInt(state.payload[0]);
     const pfn_list: mi.PfnList = @bitCast(state.payload[1]);
     const base = state.base;
@@ -36,13 +43,8 @@ fn reclaim_state(state: *ke.ShootdownState) void {
     state.release();
 }
 
-fn worker_thread(_: ?*anyopaque) void {
-    while (true) {
-        const entry = ke.shootdown.shootdowns.remove();
-        const state: *ke.ShootdownState = @fieldParentPtr("link", entry);
-
-        reclaim_state(state);
-    }
+fn reap_pages(_: ?*anyopaque) void {
+    ke.shootdown.shootdowns.process(reclaim_state, null);
 }
 
 /// Unmap and flush a virtual range on the given space.
@@ -86,7 +88,11 @@ pub fn reclaim_range(space: *mm.Space, va: r.VAddr, size: usize) void {
     };
 }
 
-pub fn init() void {
-    const td = ps.thread.create_kernel(ke.Thread.Priority.default, worker_thread, null) catch unreachable;
-    ke.sched.enqueue(&td.kern);
+fn activation(_: *rtl.HandoffList) void {
+    ex.workqueue.enqueue(&work_item);
+}
+
+pub fn init() void {
+    ke.shootdown.shootdowns.* = .init(activation);
+    work_item.init(.High, reap_pages, null);
 }