ke/sched: add pin helpers

src/ex/work.zig

@@ -130,9 +130,8 @@ const Pool = struct {
 
             td.kern.nice = -ke.Priority.nice_max;
 
-            if (cpu != null) {
+            if (cpu) |c| {
-                td.kern.last_cpu = cpu;
+                ke.sched.pin_on(&td.kern, c);
-                td.kern.pinned = true;
             }
 
             ke.sched.enqueue(&td.kern);
@@ -181,9 +180,8 @@ const Pool = struct {
             @ptrFromInt(ctx.value),
         );
 
-        if (cpu != null) {
+        if (cpu) |c| {
-            td.kern.last_cpu = cpu;
+            ke.sched.pin_on(&td.kern, c);
-            td.kern.pinned = true;
         }
 
         ke.sched.enqueue(&td.kern);

src/kern/root.zig

@@ -58,6 +58,8 @@ pub const sched = struct {
     pub const unblock = p.sched.unblock;
     pub const late_init = p.sched.late_init;
     pub const yield = p.sched.yield;
+    pub const pin = p.sched.pin;
+    pub const pin_on = p.sched.pin_on;
 };
 
 pub const timer = struct {

src/kern/sched.zig

@@ -1405,6 +1405,19 @@ pub fn update_priority_locked(td: *ke.Thread, new_prio: u8) void {
     // XXX: Handle Selected threads so that they are placed properly?
 }
 
+pub fn pin(td: *ke.Thread) void {
+    const ipl = td.lock.acquire();
+    td.pinned = true;
+    td.lock.release(ipl);
+}
+
+pub fn pin_on(td: *ke.Thread, cpu: u32) void {
+    const ipl = td.lock.acquire();
+    td.last_cpu = cpu;
+    td.pinned = true;
+    td.lock.release(ipl);
+}
+
 fn find_most_loaded(exclude: ?*ke.CpuMask, steal: bool) ?u32 {
     var most: ?u32 = null;
     var most_load: usize = 0;

src/platform/pc/smp.zig

@@ -47,7 +47,7 @@ fn make_thread(
 
     td.init(stack, size, .IdleThread, entrypoint, null);
 
-    td.pinned = true;
+    ke.sched.pin(td);
     return td;
 }