From: Thomas Gleixner <tglx@linutronix.de>
Date: Tue, 28 Mar 2023 15:49:11 +0000 (+0200)
Subject: x86/smpboot: Remove wait for cpu_online()
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=75f27e268de1f75b95e1cd8294092bdb78b25437;p=users%2Fdwmw2%2Flinux.git

x86/smpboot: Remove wait for cpu_online()

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 <tglx@linutronix.de>
---

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 925ca71fe19df..7a00092c8ba75 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1099,20 +1099,6 @@ static int wait_cpu_initialized(unsigned int cpu)
 	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);
@@ -1159,16 +1145,9 @@ int native_cpu_up(unsigned int cpu, struct task_struct *tidle)
 	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();