ARM: SMP: use a timing out completion for cpu hotplug

Rather than open-coding the jiffy-based wait, and polling for the
secondary CPU to come online, use a completion instead.  This
removes the need to poll, instead we will be notified when the
secondary CPU has initialized.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 6 insertions, 11 deletions

diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index 57db122a4f62..2b26dca2168b 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -58,6 +58,8 @@ enum ipi_msg_type {
         IPI_CPU_STOP,
 };
 
+static DECLARE_COMPLETION(cpu_running);
+
 int __cpuinit __cpu_up(unsigned int cpu)
 {
         struct cpuinfo_arm *ci = &per_cpu(cpu_data, cpu);
@@ -98,20 +100,12 @@ int __cpuinit __cpu_up(unsigned int cpu)
          */
         ret = boot_secondary(cpu, idle);
         if (ret == 0) {
-                unsigned long timeout;
-
                 /*
                  * CPU was successfully started, wait for it
                  * to come online or time out.
                  */
-                timeout = jiffies + HZ;
-                while (time_before(jiffies, timeout)) {
-                        if (cpu_online(cpu))
-                                break;
-
-                        udelay(10);
-                        barrier();
-                }
+                wait_for_completion_timeout(&cpu_running,
+                                                 msecs_to_jiffies(1000));
 
                 if (!cpu_online(cpu)) {
                         pr_crit("CPU%u: failed to come online\n", cpu);
@@ -300,9 +294,10 @@ asmlinkage void __cpuinit secondary_start_kernel(void)
         /*
          * OK, now it's safe to let the boot CPU continue.  Wait for
          * the CPU migration code to notice that the CPU is online
-         * before we continue.
+         * before we continue - which happens after __cpu_up returns.
          */
         set_cpu_online(cpu, true);
+        complete(&cpu_running);
 
         /*
          * Setup the percpu timer for this CPU.