[v3,15/36] x86/smpboot: Remove wait for cpu_online()

Commit Message

Thomas Gleixner May 8, 2023, 7:43 p.m. UTC

From: Thomas Gleixner <[e-mail]>

Now that the core code drops sparse_irq_lock after the idle thread
synchronized, it's pointless to wait for the AP to mark itself online.

Signed-off-by: Thomas Gleixner <[e-mail]>
Tested-by: Michael Kelley <[e-mail]>


---
 arch/x86/kernel/smpboot.c |   26 ++------------------------
 1 file changed, 2 insertions(+), 24 deletions(-)
---

Patch

--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -281,7 +281,6 @@  static void notrace start_secondary(void
 	 * half valid vector space.
 	 */
 	lock_vector_lock();
-	/* Sync point with do_wait_cpu_online() */
 	set_cpu_online(smp_processor_id(), true);
 	lapic_online();
 	unlock_vector_lock();
@@ -1110,20 +1109,6 @@  static int wait_cpu_initialized(unsigned
 	return 0;
 }
 
-/*
- * Bringup step three: Wait for the target AP to reach set_cpu_online() in
- * start_secondary().
- */
-static void wait_cpu_online(unsigned int cpu)
-{
-	/*
-	 * Wait for the AP to mark itself online, so the core caller
-	 * can drop sparse_irq_lock.
-	 */
-	while (!cpu_online(cpu))
-		schedule();
-}
-
 static int native_kick_ap(unsigned int cpu, struct task_struct *tidle)
 {
 	int apicid = apic->cpu_present_to_apicid(cpu);
@@ -1170,16 +1155,9 @@  int native_cpu_up(unsigned int cpu, stru
 	int ret;
 
 	ret = native_kick_ap(cpu, tidle);
-	if (ret)
-		goto out;
-
-	ret = wait_cpu_initialized(cpu);
-	if (ret)
-		goto out;
-
-	wait_cpu_online(cpu);
+	if (!ret)
+		ret = wait_cpu_initialized(cpu);
 
-out:
 	/* Cleanup possible dangling ends... */
 	if (x86_platform.legacy.warm_reset)
 		smpboot_restore_warm_reset_vector();