rcu: provide RCU options on non-preempt architectures too

Impact: build fix

Some old architectures still do not use kernel/Kconfig.preempt, so the
moving of the RCU options there broke their build:

 In file included from /home/mingo/tip/include/linux/sem.h:81,
                 from /home/mingo/tip/include/linux/sched.h:69,
                 from /home/mingo/tip/arch/alpha/kernel/asm-offsets.c:9:
 /home/mingo/tip/include/linux/rcupdate.h:62:2: error: #error "Unknown RCU implementation specified to kernel configuration"

Move these options back to init/Kconfig, which every architecture
includes.

Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/init/Kconfig b/init/Kconfig
index 9dd7958a71f0d101e67e56170ed991e8ee6a171b..6b0fdedf3596a44aabe5015af2afffc6b3c6e7ab 100644 (file)
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -928,6 +928,80 @@ source "block/Kconfig"
 config PREEMPT_NOTIFIERS
        bool
 
+choice
+       prompt "RCU Implementation"
+       default CLASSIC_RCU
+
+config CLASSIC_RCU
+       bool "Classic RCU"
+       help
+         This option selects the classic RCU implementation that is
+         designed for best read-side performance on non-realtime
+         systems.
+
+         Select this option if you are unsure.
+
+config TREE_RCU
+       bool "Tree-based hierarchical RCU"
+       help
+         This option selects the RCU implementation that is
+         designed for very large SMP system with hundreds or
+         thousands of CPUs.
+
+config PREEMPT_RCU
+       bool "Preemptible RCU"
+       depends on PREEMPT
+       help
+         This option reduces the latency of the kernel by making certain
+         RCU sections preemptible. Normally RCU code is non-preemptible, if
+         this option is selected then read-only RCU sections become
+         preemptible. This helps latency, but may expose bugs due to
+         now-naive assumptions about each RCU read-side critical section
+         remaining on a given CPU through its execution.
+
+endchoice
+
+config RCU_TRACE
+       bool "Enable tracing for RCU"
+       depends on TREE_RCU || PREEMPT_RCU
+       help
+         This option provides tracing in RCU which presents stats
+         in debugfs for debugging RCU implementation.
+
+         Say Y here if you want to enable RCU tracing
+         Say N if you are unsure.
+
+config RCU_FANOUT
+       int "Tree-based hierarchical RCU fanout value"
+       range 2 64 if 64BIT
+       range 2 32 if !64BIT
+       depends on TREE_RCU
+       default 64 if 64BIT
+       default 32 if !64BIT
+       help
+         This option controls the fanout of hierarchical implementations
+         of RCU, allowing RCU to work efficiently on machines with
+         large numbers of CPUs.  This value must be at least the cube
+         root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit
+         systems and up to 262,144 for 64-bit systems.
+
+         Select a specific number if testing RCU itself.
+         Take the default if unsure.
+
+config RCU_FANOUT_EXACT
+       bool "Disable tree-based hierarchical RCU auto-balancing"
+       depends on TREE_RCU
+       default n
+       help
+         This option forces use of the exact RCU_FANOUT value specified,
+         regardless of imbalances in the hierarchy.  This is useful for
+         testing RCU itself, and might one day be useful on systems with
+         strong NUMA behavior.
+
+         Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
+
+         Say N if unsure.
+
 config TREE_RCU_TRACE
        def_bool RCU_TRACE && TREE_RCU
        select DEBUG_FS

diff --git a/kernel/Kconfig.preempt b/kernel/Kconfig.preempt
index 463f29743ea01c6b6da4589dedcf45ead8cc5541..bf987b95b3560fbd0a7d8a820335100a55e1d105 100644 (file)
--- a/kernel/Kconfig.preempt
+++ b/kernel/Kconfig.preempt
@@ -52,78 +52,3 @@ config PREEMPT
 
 endchoice
 
-choice
-       prompt "RCU Implementation"
-       default CLASSIC_RCU
-
-config CLASSIC_RCU
-       bool "Classic RCU"
-       help
-         This option selects the classic RCU implementation that is
-         designed for best read-side performance on non-realtime
-         systems.
-         
-         Select this option if you are unsure.
-
-config TREE_RCU
-       bool "Tree-based hierarchical RCU"
-       help
-         This option selects the RCU implementation that is
-         designed for very large SMP system with hundreds or
-         thousands of CPUs.
-
-config PREEMPT_RCU
-       bool "Preemptible RCU"
-       depends on PREEMPT
-       help
-         This option reduces the latency of the kernel by making certain
-         RCU sections preemptible. Normally RCU code is non-preemptible, if
-         this option is selected then read-only RCU sections become
-         preemptible. This helps latency, but may expose bugs due to
-         now-naive assumptions about each RCU read-side critical section
-         remaining on a given CPU through its execution.
-
-endchoice
-
-config RCU_TRACE
-       bool "Enable tracing for RCU"
-       depends on TREE_RCU || PREEMPT_RCU
-       help
-         This option provides tracing in RCU which presents stats
-         in debugfs for debugging RCU implementation.
-
-         Say Y here if you want to enable RCU tracing
-         Say N if you are unsure.
-
-config RCU_FANOUT
-       int "Tree-based hierarchical RCU fanout value"
-       range 2 64 if 64BIT
-       range 2 32 if !64BIT
-       depends on TREE_RCU
-       default 64 if 64BIT
-       default 32 if !64BIT
-       help
-         This option controls the fanout of hierarchical implementations
-         of RCU, allowing RCU to work efficiently on machines with
-         large numbers of CPUs.  This value must be at least the cube
-         root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit
-         systems and up to 262,144 for 64-bit systems.
-
-         Select a specific number if testing RCU itself.
-         Take the default if unsure.
-
-config RCU_FANOUT_EXACT
-       bool "Disable tree-based hierarchical RCU auto-balancing"
-       depends on TREE_RCU
-       default n
-       help
-         This option forces use of the exact RCU_FANOUT value specified,
-         regardless of imbalances in the hierarchy.  This is useful for
-         testing RCU itself, and might one day be useful on systems with
-         strong NUMA behavior.
-
-         Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
-
-         Say n if unsure.
-
-