From 149c24151e8577b2a033639722dc5734de5e6eaf Mon Sep 17 00:00:00 2001 From: Russell King Date: Wed, 18 Jan 2012 15:59:45 +0000 Subject: [PATCH] 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 --- arch/arm/kernel/smp.c | 17 ++++++----------- 1 file 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. -- 2.20.1