Revert "x86/smpboot: Initialize secondary CPU only if master CPU will wait for it"

This reverts commit 3e1a878b7ccdb31da6d9d2b855c72ad87afeba3f.

It came in very late, and already has one reported failure: Sitsofe
reports that the current tree fails to boot on his EeePC, and bisected
it down to this.  Rather than waste time trying to figure out what's
wrong, just revert it.

Reported-by: Sitsofe Wheeler <sitsofe@gmail.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Toshi Kani <toshi.kani@hp.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 11 insertions, 16 deletions

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index a4bcbacdbe0b..a135239badb7 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1221,17 +1221,6 @@ static void dbg_restore_debug_regs(void)
 #define dbg_restore_debug_regs()
 #endif /* ! CONFIG_KGDB */
 
-static void wait_for_master_cpu(int cpu)
-{
-        /*
-         * wait for ACK from master CPU before continuing
-         * with AP initialization
-         */
-        WARN_ON(cpumask_test_and_set_cpu(cpu, cpu_initialized_mask));
-        while (!cpumask_test_cpu(cpu, cpu_callout_mask))
-                cpu_relax();
-}
-
 /*
  * cpu_init() initializes state that is per-CPU. Some data is already
  * initialized (naturally) in the bootstrap process, such as the GDT
@@ -1247,17 +1236,16 @@ void cpu_init(void)
         struct task_struct *me;
         struct tss_struct *t;
         unsigned long v;
-        int cpu = stack_smp_processor_id();
+        int cpu;
         int i;
 
-        wait_for_master_cpu(cpu);
-
         /*
          * Load microcode on this cpu if a valid microcode is available.
          * This is early microcode loading procedure.
          */
         load_ucode_ap();
 
+        cpu = stack_smp_processor_id();
         t = &per_cpu(init_tss, cpu);
         oist = &per_cpu(orig_ist, cpu);
 
@@ -1269,6 +1257,9 @@ void cpu_init(void)
 
         me = current;
 
+        if (cpumask_test_and_set_cpu(cpu, cpu_initialized_mask))
+                panic("CPU#%d already initialized!\n", cpu);
+
         pr_debug("Initializing CPU#%d\n", cpu);
 
         clear_in_cr4(X86_CR4_VME|X86_CR4_PVI|X86_CR4_TSD|X86_CR4_DE);
@@ -1345,10 +1336,14 @@ void cpu_init(void)
         struct tss_struct *t = &per_cpu(init_tss, cpu);
         struct thread_struct *thread = &curr->thread;
 
-        wait_for_master_cpu(cpu);
-
         show_ucode_info_early();
 
+        if (cpumask_test_and_set_cpu(cpu, cpu_initialized_mask)) {
+                printk(KERN_WARNING "CPU#%d already initialized!\n", cpu);
+                for (;;)
+                        local_irq_enable();
+        }
+
         printk(KERN_INFO "Initializing CPU#%d\n", cpu);
 
         if (cpu_has_vme || cpu_has_tsc || cpu_has_de)