x86/smp: Fix cpuN startup panic

From: Lin Chen <[email protected]>

We hit a panic while doing cpu hotplug test.

<0>[  627.982857] Kernel panic - not syncing: smp_callin: CPU1 started up but did not get a callout!
<0>[  627.982864]
<4>[  627.982876] Pid: 0, comm: kworker/0:1 Tainted: G ...
<4>[  627.982883] Call Trace:
<4>[  627.982903]  [<c18f2977>] panic+0x66/0x16c
<4>[  627.982918]  [<c12234cc>] ? default_get_apic_id+0x1c/0x40
<4>[  627.982931]  [<c18ef96d>] start_secondary+0xda/0x252

During BSP bootup AP, it is possible that BSP be preempted before finishing STARTUP sequence of AP(set cpu_callout_mask) which maybe cause AP busy wait for it. At present, AP will wait for 2 seconds then panic.

This patch let AP waits for 60 seconds at maximum.

---
 arch/x86/kernel/smpboot.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

index 7c5a8c3..447aa3b 100644
@@ -162,9 +162,9 @@ static void __cpuinit smp_callin(void)
 	 */
 
 	/*
-	 * Waiting 2s total for startup (udelay is not yet working)
+	 * Waiting 60s total for startup (udelay is not yet working)
 	 */
-	timeout = jiffies + 2*HZ;
+	timeout = jiffies + 60*HZ;
 	while (time_before(jiffies, timeout)) {
 		/*
 		 * Has the boot CPU finished it's STARTUP sequence?

1.7.1