rcu: Make SRCU optional by using CONFIG_SRCU

SRCU is not necessary to be compiled by default in all cases. For tinification
efforts not compiling SRCU unless necessary is desirable.

The current patch tries to make compiling SRCU optional by introducing a new
Kconfig option CONFIG_SRCU which is selected when any of the components making
use of SRCU are selected.

If we do not select CONFIG_SRCU, srcu.o will not be compiled at all.

   text    data     bss     dec     hex filename
   2007       0       0    2007     7d7 kernel/rcu/srcu.o

Size of arch/powerpc/boot/zImage changes from

   text    data     bss     dec     hex filename
 831552   64180   23944  919676   e087c arch/powerpc/boot/zImage : before
 829504   64180   23952  917636   e0084 arch/powerpc/boot/zImage : after

so the savings are about ~2000 bytes.

Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
CC: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
CC: Josh Triplett <josh@joshtriplett.org>
CC: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
[ paulmck: resolve conflict due to removal of arch/ia64/kvm/Kconfig. ]
(cherry picked from commit 83fe27ea531161a655f02dc7732d14cfaa27fd5d)

diff --git a/arch/arm/kvm/Kconfig b/arch/arm/kvm/Kconfig
index 466bd299b1a8aad54949364d976d9c5430c2375e..3afee5f40f4f1d7ff6d10b6a95b1b6434415c63e 100644 (file)
--- a/arch/arm/kvm/Kconfig
+++ b/arch/arm/kvm/Kconfig
@@ -23,6 +23,7 @@ config KVM
        select HAVE_KVM_CPU_RELAX_INTERCEPT
        select KVM_MMIO
        select KVM_ARM_HOST
+       select SRCU
        depends on ARM_VIRT_EXT && ARM_LPAE
        ---help---
          Support hosting virtualized guest machines. You will also

diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
index 8ba85e9ea388d1778c54eabdd5ca34afad114faf..b334084d3675e33761ec618b9f776650c02f2251 100644 (file)
--- a/arch/arm64/kvm/Kconfig
+++ b/arch/arm64/kvm/Kconfig
@@ -26,6 +26,7 @@ config KVM
        select KVM_ARM_HOST
        select KVM_ARM_VGIC
        select KVM_ARM_TIMER
+       select SRCU
        ---help---
          Support hosting virtualized guest machines.
 

diff --git a/arch/mips/kvm/Kconfig b/arch/mips/kvm/Kconfig
index 30e334e823bd60822285efa9da808a991e6e19bb..2ae12825529f8fe37e6e6b13c79eee39d4c4753c 100644 (file)
--- a/arch/mips/kvm/Kconfig
+++ b/arch/mips/kvm/Kconfig
@@ -20,6 +20,7 @@ config KVM
        select PREEMPT_NOTIFIERS
        select ANON_INODES
        select KVM_MMIO
+       select SRCU
        ---help---
          Support for hosting Guest kernels.
          Currently supported on MIPS32 processors.

diff --git a/arch/powerpc/kvm/Kconfig b/arch/powerpc/kvm/Kconfig
index f5769f19ae256906dd750dd6fcd4ad5448e55bbd..11850f310fb41fb50c639e558da1921a167af7ac 100644 (file)
--- a/arch/powerpc/kvm/Kconfig
+++ b/arch/powerpc/kvm/Kconfig
@@ -21,6 +21,7 @@ config KVM
        select PREEMPT_NOTIFIERS
        select ANON_INODES
        select HAVE_KVM_EVENTFD
+       select SRCU
 
 config KVM_BOOK3S_HANDLER
        bool

diff --git a/arch/s390/kvm/Kconfig b/arch/s390/kvm/Kconfig
index 646db9c467d136d211650b0d6cdaea63ff85d2a1..5fce52cf0e57dc4831d0737ddd3c3a2cfbc386d7 100644 (file)
--- a/arch/s390/kvm/Kconfig
+++ b/arch/s390/kvm/Kconfig
@@ -28,6 +28,7 @@ config KVM
        select HAVE_KVM_IRQCHIP
        select HAVE_KVM_IRQFD
        select HAVE_KVM_IRQ_ROUTING
+       select SRCU
        ---help---
          Support hosting paravirtualized guest machines using the SIE
          virtualization capability on the mainframe. This should work

diff --git a/arch/tile/kvm/Kconfig b/arch/tile/kvm/Kconfig
index 2298cb1daff74e411ac0a616252e84988bfdd06f..1e968f7550dc0363c0ddff9d68626cd59afb119c 100644 (file)
--- a/arch/tile/kvm/Kconfig
+++ b/arch/tile/kvm/Kconfig
@@ -21,6 +21,7 @@ config KVM
        depends on HAVE_KVM && MODULES
        select PREEMPT_NOTIFIERS
        select ANON_INODES
+       select SRCU
        ---help---
          Support hosting paravirtualized guest machines.
 

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 0dc9d0144a27957d2bd2cdadf3b141a3195ccab0..85588a891c063a8910778c3deff07edfb97f6714 100644 (file)
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -138,6 +138,7 @@ config X86
        select HAVE_ACPI_APEI_NMI if ACPI
        select ACPI_LEGACY_TABLES_LOOKUP if ACPI
        select X86_FEATURE_NAMES if PROC_FS
+       select SRCU
 
 config INSTRUCTION_DECODER
        def_bool y

diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
index f9d16ff56c6b18df942da02b08aa6fc20fbc6068..7dc7ba577ecded7fcc2b8f77b480200f68b6433a 100644 (file)
--- a/arch/x86/kvm/Kconfig
+++ b/arch/x86/kvm/Kconfig
@@ -40,6 +40,7 @@ config KVM
        select HAVE_KVM_MSI
        select HAVE_KVM_CPU_RELAX_INTERCEPT
        select KVM_VFIO
+       select SRCU
        ---help---
          Support hosting fully virtualized guest machines using hardware
          virtualization extensions.  You will need a fairly recent

diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
index 3f44f292d066f03c2bd3029f4631d3a5183a70de..91f86131bb7aa62b0c4632e2defa1f8b2f4e6abc 100644 (file)
--- a/drivers/clk/Kconfig
+++ b/drivers/clk/Kconfig
@@ -13,6 +13,7 @@ config COMMON_CLK
        bool
        select HAVE_CLK_PREPARE
        select CLKDEV_LOOKUP
+       select SRCU
        ---help---
          The common clock framework is a single definition of struct
          clk, useful across many platforms, as well as an

diff --git a/drivers/cpufreq/Kconfig b/drivers/cpufreq/Kconfig
index 29b2ef5a68b9318b3791c37e8e1b94c12b6553d6..a171fef2c2b66d0732e01f349f9fa13b01f8af2e 100644 (file)
--- a/drivers/cpufreq/Kconfig
+++ b/drivers/cpufreq/Kconfig
@@ -2,6 +2,7 @@ menu "CPU Frequency scaling"
 
 config CPU_FREQ
        bool "CPU Frequency scaling"
+       select SRCU
        help
          CPU Frequency scaling allows you to change the clock speed of 
          CPUs on the fly. This is a nice method to save power, because 

diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig
index faf4e70c42e0467f072cde73d6cc972ff27509ae..3891f6781298c39aee61e68010bf6f42396def1f 100644 (file)
--- a/drivers/devfreq/Kconfig
+++ b/drivers/devfreq/Kconfig
@@ -1,5 +1,6 @@
 menuconfig PM_DEVFREQ
        bool "Generic Dynamic Voltage and Frequency Scaling (DVFS) support"
+       select SRCU
        help
          A device may have a list of frequencies and voltages available.
          devfreq, a generic DVFS framework can be registered for a device

diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
index 5bdedf6df153cf25d54e91a2cca5d9e3b6b8b1cf..c355a226a0247c824770457179731bc05d3a0667 100644 (file)
--- a/drivers/md/Kconfig
+++ b/drivers/md/Kconfig
@@ -5,6 +5,7 @@
 menuconfig MD
        bool "Multiple devices driver support (RAID and LVM)"
        depends on BLOCK
+       select SRCU
        help
          Support multiple physical spindles through a single logical device.
          Required for RAID and logical volume management.

diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
index d6607ee9c85506bb4fcc5d2077b8dc4e582d4b4b..84673ebcf428846fadf26ae881c39172fd45d612 100644 (file)
--- a/drivers/net/Kconfig
+++ b/drivers/net/Kconfig
@@ -197,6 +197,7 @@ config NETCONSOLE_DYNAMIC
 
 config NETPOLL
        def_bool NETCONSOLE
+       select SRCU
 
 config NET_POLL_CONTROLLER
        def_bool NETPOLL

diff --git a/fs/btrfs/Kconfig b/fs/btrfs/Kconfig
index a66768ebc8d19d394f2cd0818d56178a50f84803..80e9c18ea64f69b68f84e3953256654774bd0b7e 100644 (file)
--- a/fs/btrfs/Kconfig
+++ b/fs/btrfs/Kconfig
@@ -8,6 +8,7 @@ config BTRFS_FS
        select LZO_DECOMPRESS
        select RAID6_PQ
        select XOR_BLOCKS
+       select SRCU
 
        help
          Btrfs is a general purpose copy-on-write filesystem with extents,

diff --git a/fs/notify/Kconfig b/fs/notify/Kconfig
index 22c629eedd82d70425704ee86b4ddf816b7bd174..2a24249b30af845d4514552da47fb94e70765db3 100644 (file)
--- a/fs/notify/Kconfig
+++ b/fs/notify/Kconfig
@@ -1,5 +1,6 @@
 config FSNOTIFY
        def_bool n
+       select SRCU
 
 source "fs/notify/dnotify/Kconfig"
 source "fs/notify/inotify/Kconfig"

diff --git a/fs/quota/Kconfig b/fs/quota/Kconfig
index c51df1dd237e74a0127da81f95d77f570d463b84..4a09975aac907e563182879362f816d36773f481 100644 (file)
--- a/fs/quota/Kconfig
+++ b/fs/quota/Kconfig
@@ -5,6 +5,7 @@
 config QUOTA
        bool "Quota support"
        select QUOTACTL
+       select SRCU
        help
          If you say Y here, you will be able to set per user limits for disk
          usage (also called disk quotas). Currently, it works for the

diff --git a/init/Kconfig b/init/Kconfig
index 9afb971497f4c9972b0dcf14071edf9ef81320be..f085969ba340bfdc21e2a8ba16a6eb4c8feb4c1a 100644 (file)
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -501,9 +501,17 @@ config TINY_RCU
 
 endchoice
 
+config SRCU
+       bool
+       help
+         This option selects the sleepable version of RCU. This version
+         permits arbitrary sleeping or blocking within RCU read-side critical
+         sections.
+
 config TASKS_RCU
        bool "Task_based RCU implementation using voluntary context switch"
        default n
+       select SRCU
        help
          This option enables a task-based RCU implementation that uses
          only voluntary context switch (not preemption!), idle, and
@@ -1595,6 +1603,7 @@ config PERF_EVENTS
        depends on HAVE_PERF_EVENTS
        select ANON_INODES
        select IRQ_WORK
+       select SRCU
        help
          Enable kernel support for various performance events provided
          by software and hardware.

diff --git a/kernel/notifier.c b/kernel/notifier.c
index 4803da6eab62f182354707c10f48be35a8b54fb5..ae9fc7cc360ebea6088db4ae0206e452d856214b 100644 (file)
--- a/kernel/notifier.c
+++ b/kernel/notifier.c
@@ -402,6 +402,7 @@ int raw_notifier_call_chain(struct raw_notifier_head *nh,
 }
 EXPORT_SYMBOL_GPL(raw_notifier_call_chain);
 
+#ifdef CONFIG_SRCU
 /*
  *     SRCU notifier chain routines.    Registration and unregistration
  *     use a mutex, and call_chain is synchronized by SRCU (no locks).
@@ -528,6 +529,8 @@ void srcu_init_notifier_head(struct srcu_notifier_head *nh)
 }
 EXPORT_SYMBOL_GPL(srcu_init_notifier_head);
 
+#endif /* CONFIG_SRCU */
+
 static ATOMIC_NOTIFIER_HEAD(die_chain);
 
 int notrace notify_die(enum die_val val, const char *str,

diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
index 48b28d387c7f77b2e3d36bc751b3e221c7634d67..7e01f78f041778abe405c9115c15e10a77f64d03 100644 (file)
--- a/kernel/power/Kconfig
+++ b/kernel/power/Kconfig
@@ -251,6 +251,7 @@ config APM_EMULATION
 
 config PM_OPP
        bool
+       select SRCU
        ---help---
          SOCs have a standard set of tuples consisting of frequency and
          voltage pairs that the device will support per voltage domain. This

diff --git a/kernel/rcu/Makefile b/kernel/rcu/Makefile
index e6fae503d1bc54519a45ba838fe3d8622e4333f4..50a808424b06af45fdd0fd6ab3ae732e1917680d 100644 (file)
--- a/kernel/rcu/Makefile
+++ b/kernel/rcu/Makefile
@@ -1,4 +1,5 @@
-obj-y += update.o srcu.o
+obj-y += update.o
+obj-$(CONFIG_SRCU) += srcu.o
 obj-$(CONFIG_RCU_TORTURE_TEST) += rcutorture.o
 obj-$(CONFIG_TREE_RCU) += tree.o
 obj-$(CONFIG_PREEMPT_RCU) += tree.o

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 5f2ce616c0462db9b9055528110268385b2b653e..7a9c93e327f23b931407c9673d22a6e257fb0579 100644 (file)
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1215,6 +1215,7 @@ config RCU_TORTURE_TEST
        tristate "torture tests for RCU"
        depends on DEBUG_KERNEL
        select TORTURE_TEST
+       select SRCU
        default n
        help
          This option provides a kernel module that runs torture tests

diff --git a/mm/Kconfig b/mm/Kconfig
index 1d1ae6b078fdd9121abbd01409f01437bb67e1e8..4395b12869c832dba4a62747658f2238dd1257f7 100644 (file)
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -325,6 +325,7 @@ config VIRT_TO_BUS
 
 config MMU_NOTIFIER
        bool
+       select SRCU
 
 config KSM
        bool "Enable KSM for page merging"

diff --git a/security/tomoyo/Kconfig b/security/tomoyo/Kconfig
index 8eb779b9d77f2ad56c7ccdc5db081bc4b0a05028..604e718d68d35ecb305b3ad71ae774a848ea5a02 100644 (file)
--- a/security/tomoyo/Kconfig
+++ b/security/tomoyo/Kconfig
@@ -5,6 +5,7 @@ config SECURITY_TOMOYO
        select SECURITYFS
        select SECURITY_PATH
        select SECURITY_NETWORK
+       select SRCU
        default n
        help
          This selects TOMOYO Linux, pathname-based access control.