intel_idle: Convert i7300_idle_lock to raw_spinlock

24 core Intel box's first exposure to 3.0.12-rt30-rc3 didn't go well.

[   27.104159] i7300_idle: loaded v1.55
[   27.104192] BUG: scheduling while atomic: swapper/2/0/0x00000002
[   27.104309] Pid: 0, comm: swapper/2 Tainted: G           N  3.0.12-rt30-rc3-rt #1
[   27.104317] Call Trace:
[   27.104338]  [<ffffffff810046a5>] dump_trace+0x85/0x2e0
[   27.104372]  [<ffffffff8144eb00>] thread_return+0x12b/0x30b
[   27.104381]  [<ffffffff8144f1b9>] schedule+0x29/0xb0
[   27.104389]  [<ffffffff814506e5>] rt_spin_lock_slowlock+0xc5/0x240
[   27.104401]  [<ffffffffa01f818f>] i7300_idle_notifier+0x3f/0x360 [i7300_idle]
[   27.104415]  [<ffffffff814546c7>] notifier_call_chain+0x37/0x70
[   27.104426]  [<ffffffff81454748>] __atomic_notifier_call_chain+0x48/0x70
[   27.104439]  [<ffffffff81001a39>] cpu_idle+0x89/0xb0
[   27.104449] bad: scheduling from the idle thread!

This lock is taken from interrupt disabled context in the guts of
idle. Convert it to a raw_spinlock.

Signed-off-by: Mike Galbraith <efault@gmx.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Andy Henroid <andrew.d.henroid@intel.com>
Link: http://lkml.kernel.org/r/1323258522.5057.73.camel@marge.simson.net
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

drivers/idle/i7300_idle.c

@@ -75,7 +75,7 @@ static unsigned long past_skip;
 
 static struct pci_dev *fbd_dev;
 
-static spinlock_t i7300_idle_lock;
+static raw_spinlock_t i7300_idle_lock;
 static int i7300_idle_active;
 
 static u8 i7300_idle_thrtctl_saved;
@@ -457,7 +457,7 @@ static int i7300_idle_notifier(struct notifier_block *nb, unsigned long val,
 		idle_begin_time = ktime_get();
 	}
 
-	spin_lock_irqsave(&i7300_idle_lock, flags);
+	raw_spin_lock_irqsave(&i7300_idle_lock, flags);
 	if (val == IDLE_START) {
 
 		cpumask_set_cpu(smp_processor_id(), idle_cpumask);
@@ -506,7 +506,7 @@ static int i7300_idle_notifier(struct notifier_block *nb, unsigned long val,
 		}
 	}
 end:
-	spin_unlock_irqrestore(&i7300_idle_lock, flags);
+	raw_spin_unlock_irqrestore(&i7300_idle_lock, flags);
 	return 0;
 }
 
@@ -548,7 +548,7 @@ struct debugfs_file_info {
 
 static int __init i7300_idle_init(void)
 {
-	spin_lock_init(&i7300_idle_lock);
+	raw_spin_lock_init(&i7300_idle_lock);
 	total_us = 0;
 
 	if (i7300_idle_platform_probe(&fbd_dev, &ioat_dev, forceload))