Commit 83fe27ea authored by Pranith Kumar's avatar Pranith Kumar Committed by Paul E. McKenney

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: default avatarPranith 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: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
[ paulmck: resolve conflict due to removal of arch/ia64/kvm/Kconfig. ]
parent 9735af5c
......@@ -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
......
......@@ -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.
......
......@@ -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.
......
......@@ -21,6 +21,7 @@ config KVM
select PREEMPT_NOTIFIERS
select ANON_INODES
select HAVE_KVM_EVENTFD
select SRCU
config KVM_BOOK3S_HANDLER
bool
......
......@@ -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
......
......@@ -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.
......
......@@ -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
......
......@@ -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
......
......@@ -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
......
......@@ -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
......
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
......
......@@ -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.
......
......@@ -197,6 +197,7 @@ config NETCONSOLE_DYNAMIC
config NETPOLL
def_bool NETCONSOLE
select SRCU
config NET_POLL_CONTROLLER
def_bool NETPOLL
......
......@@ -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,
......
config FSNOTIFY
def_bool n
select SRCU
source "fs/notify/dnotify/Kconfig"
source "fs/notify/inotify/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
......
......@@ -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.
......
......@@ -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,
......
......@@ -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
......
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
......
......@@ -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
......
......@@ -325,6 +325,7 @@ config VIRT_TO_BUS
config MMU_NOTIFIER
bool
select SRCU
config KSM
bool "Enable KSM for page merging"
......
......@@ -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.
......
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