[PATCH RFC] pm_qos_requirement might sleep

["John Kacur" <jkacur@gmail.com>]

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Even after applying some fixes posted by Chirag and Peter Z, I'm still
getting some messages in my log like this
BUG: sleeping function called from invalid context swapper(0) at
kernel/rtmutex.c:743
in_atomic():1 [00000001], irqs_disabled():1
Pid: 0, comm: swapper Tainted: G        W 2.6.26.1-rt1.jk #2

Call Trace:
 [<ffffffff802305d3>] __might_sleep+0x12d/0x132
 [<ffffffff8046cdbe>] __rt_spin_lock+0x34/0x7d
 [<ffffffff8046ce15>] rt_spin_lock+0xe/0x10
 [<ffffffff802532e5>] pm_qos_requirement+0x1f/0x3c
 [<ffffffff803e1b7f>] menu_select+0x7b/0x9c
 [<ffffffff8020b1be>] ? default_idle+0x0/0x5a
 [<ffffffff8020b1be>] ? default_idle+0x0/0x5a
 [<ffffffff803e0b4b>] cpuidle_idle_call+0x68/0xd8
 [<ffffffff803e0ae3>] ? cpuidle_idle_call+0x0/0xd8
 [<ffffffff8020b1be>] ? default_idle+0x0/0x5a
 [<ffffffff8020b333>] cpu_idle+0xb2/0x12d
 [<ffffffff80466af0>] start_secondary+0x186/0x18b

---------------------------
| preempt count: 00000001 ]
| 1-level deep critical section nesting:
----------------------------------------
.. [<ffffffff8020b39c>] .... cpu_idle+0x11b/0x12d
.....[<ffffffff80466af0>] ..   ( <= start_secondary+0x186/0x18b)

The following simple patch makes the messages disappear - however,
there may be a better more fine grained solution, but the problem is
also that all the functions are designed to use the same lock.

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pm_qos_requirement-fix
Signed-off-by: John Kacur <jkacur at gmail dot com>

Index: linux-2.6.26.1-jk-rt1/kernel/pm_qos_params.c
===================================================================
--- linux-2.6.26.1-jk-rt1.orig/kernel/pm_qos_params.c
+++ linux-2.6.26.1-jk-rt1/kernel/pm_qos_params.c
@@ -110,7 +110,7 @@ static struct pm_qos_object *pm_qos_arra
 	&network_throughput_pm_qos
 };
 
-static DEFINE_SPINLOCK(pm_qos_lock);
+static DEFINE_RAW_SPINLOCK(pm_qos_lock);
 
 static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
 		size_t count, loff_t *f_pos);