cpu/hotplug: Handle early registration gracefully

We switched the hotplug machinery to smpboot threads. Early registration of hotplug callbacks, i.e. from do_pre_smp_initcalls(), happens before the threads are initialized. Instead of moving the thread init, we simply handle it in the hotplug code itself and invoke the function directly. Signed-off-by: Thomas Gleixner <[email protected]> Signed-off-by: Anna-Maria Gleixner <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: [email protected] Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]>
oohal · Jul 14, 2016 · 6a4e245 · 6a4e245
1 parent e877bde
commit 6a4e245
Showing 1 changed file with 7 additions and 0 deletions.
diff --git a/kernel/cpu.c b/kernel/cpu.c
@@ -517,6 +517,13 @@ static int cpuhp_invoke_ap_callback(int cpu, enum cpuhp_state state,
 	if (!cpu_online(cpu))
 		return 0;
 
+	/*
+	 * If we are up and running, use the hotplug thread. For early calls
+	 * we invoke the thread function directly.
+	 */
+	if (!st->thread)
+		return cpuhp_invoke_callback(cpu, state, cb);
+
 	st->cb_state = state;
 	st->cb = cb;
 	/*