[PATCH] rt Kconfig.preempt fixes

[John Kacur]

This is a non-critical patch, that makes configuring an rt kernel a
little nicer.
Comments are welcome of course.

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

This patch makes the following changes.
1. Hides the visibility of PREEMPT_SOFTIRQS and PREEMPT_HARDIRQS if PREEMPT_RT
(Complete Preemption) is choosen, since these values are then set (selected) to
be "y".

2. Changes the PREEMPT_HARDIRQS to depend on PREEMPT_SOFTIRQS instead of
forcing PREEMPT_SOFTIRQS to y if PREEMPT_HARDIRQS is choosen. (this is somewhat
an abuse of select)

3. Minor spelling fix. (tat to that)
Signed-off-by: John Kacur <jkacur at gmail dot com>

This patch makes the following changes.
1. Hides the visibility of PREEMPT_SOFTIRQS and PREEMPT_HARDIRQS if PREEMPT_RT
(Complete Preemption) is choosen, since these values are then set (selected) to
be "y".

2. Changes the PREEMPT_HARDIRQS to depend on PREEMPT_SOFTIRQS instead of
forcing PREEMPT_SOFTIRQS to y if PREEMPT_HARDIRQS is choosen. (this is somewhat
an abuse of select)

3. Minor spelling fix. (tat to that)

Index: linux-2.6.26-rt1/kernel/Kconfig.preempt
===================================================================
--- linux-2.6.26-rt1.orig/kernel/Kconfig.preempt
+++ linux-2.6.26-rt1/kernel/Kconfig.preempt
@@ -88,8 +88,10 @@ config PREEMPT
 
 config PREEMPT_SOFTIRQS
 	bool "Thread Softirqs"
+# The following line makes PREEMPT_SOFTIRQS invisible if PREEMPT_RT is y
+# However, PREEMPT_RT still sets (selects) the value of PREEMPT_SOFTIRQS to y
+	depends on PREEMPT_RT != y
 	default n
-#	depends on PREEMPT
 	help
 	  This option reduces the latency of the kernel by 'threading'
           soft interrupts. This means that all softirqs will execute
@@ -104,9 +106,12 @@ config PREEMPT_SOFTIRQS
 
 config PREEMPT_HARDIRQS
 	bool "Thread Hardirqs"
+# The following line makes PREEMPT_HARDIRQS invisible if PREEMPT_RT is y
+# However, PREEMPT_RT still sets (selects) the value of PREEMPT_HARDIRQS to y
+	depends on PREEMPT_RT != y
 	default n
 	depends on !GENERIC_HARDIRQS_NO__DO_IRQ
-	select PREEMPT_SOFTIRQS
+	depends on PREEMPT_SOFTIRQS
 	help
 	  This option reduces the latency of the kernel by 'threading'
           hardirqs. This means that all (or selected) hardirqs will run
@@ -141,7 +146,7 @@ config PREEMPT_RCU_BOOST
 	default y if PREEMPT_RT
 	help
 	  This option permits priority boosting of RCU read-side critical
-	  sections tat have been preempted and a RT process is waiting
+	  sections that have been preempted and a RT process is waiting
 	  on a synchronize_rcu.
 
 	  An RCU thread is also created that periodically wakes up and