Re: [PATCH] tinification: Make SRCU optional by using CONFIG_SRCU

From: Paul E. McKenney
Date: Thu Dec 04 2014 - 19:12:02 EST

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On Thu, Dec 04, 2014 at 06:50:24PM -0500, Pranith Kumar wrote:
> 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@xxxxxxxxx>
> CC: Paul McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
> CC: Josh Triplett <josh@xxxxxxxxxxxxxxxx>

I have queued this for testing.

Josh, does this look reasonable to you?

Lai, any issues?

Thanx, Paul

> ---
> arch/arm/kvm/Kconfig | 1 +
> arch/arm64/kvm/Kconfig | 1 +
> arch/ia64/kvm/Kconfig | 1 +
> arch/mips/kvm/Kconfig | 1 +
> arch/powerpc/kvm/Kconfig | 1 +
> arch/s390/kvm/Kconfig | 1 +
> arch/tile/kvm/Kconfig | 1 +
> arch/x86/Kconfig | 1 +
> arch/x86/kvm/Kconfig | 1 +
> drivers/clk/Kconfig | 1 +
> drivers/cpufreq/Kconfig | 1 +
> drivers/devfreq/Kconfig | 1 +
> drivers/md/Kconfig | 1 +
> drivers/net/Kconfig | 1 +
> fs/btrfs/Kconfig | 1 +
> fs/notify/Kconfig | 1 +
> init/Kconfig | 10 ++++++++++
> kernel/notifier.c | 3 +++
> kernel/rcu/Makefile | 3 ++-
> lib/Kconfig.debug | 1 +
> mm/Kconfig | 1 +
> security/tomoyo/Kconfig | 1 +
> 22 files changed, 34 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm/kvm/Kconfig b/arch/arm/kvm/Kconfig
> index 466bd29..3afee5f 100644
> --- 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 8ba85e9..b334084 100644
> --- 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/ia64/kvm/Kconfig b/arch/ia64/kvm/Kconfig
> index 3d50ea9..f7d380b 100644
> --- a/arch/ia64/kvm/Kconfig
> +++ b/arch/ia64/kvm/Kconfig
> @@ -29,6 +29,7 @@ config KVM
> select HAVE_KVM_IRQ_ROUTING
> select KVM_APIC_ARCHITECTURE
> select KVM_MMIO
> + select SRCU
> ---help---
> Support hosting fully virtualized guest machines using hardware
> virtualization extensions. You will need a fairly recent
> diff --git a/arch/mips/kvm/Kconfig b/arch/mips/kvm/Kconfig
> index 30e334e..2ae1282 100644
> --- 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 602eb51..af18e0f 100644
> --- 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 646db9c..5fce52c 100644
> --- 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 2298cb1..1e968f7 100644
> --- 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 ded8a67..1c581a0 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -137,6 +137,7 @@ 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 f9d16ff..7dc7ba5 100644
> --- 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 455fd17..53e64f1 100644
> --- 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 3489f8f..ebaa0cc 100644
> --- 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 faf4e70..3891f67 100644
> --- 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 5bdedf6..c355a22 100644
> --- 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 f9009be..1c7efb1 100644
> --- a/drivers/net/Kconfig
> +++ b/drivers/net/Kconfig
> @@ -177,6 +177,7 @@ 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 a66768e..80e9c18 100644
> --- 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 22c629e..2a24249 100644
> --- 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/init/Kconfig b/init/Kconfig
> index 903505e..100f4e7 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -501,9 +501,18 @@ config TINY_RCU
>
> endchoice
>
> +config SRCU
> + bool "Sleepable form of RCU"
> + def_bool n
> + 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
> @@ -1593,6 +1602,7 @@ 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 4803da6..ae9fc7c 100644
> --- 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/rcu/Makefile b/kernel/rcu/Makefile
> index e6fae50..50a8084 100644
> --- 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 d780351..ce76f34 100644
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -1199,6 +1199,7 @@ 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 1d1ae6b..4395b12 100644
> --- 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 8eb779b9d..604e718 100644
> --- 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.
> --
> 1.9.1
>

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Next message: Andrew Morton: "Re: [RESEND PATCHv2] drivers/rtc/rtc-snvs: Add clock support"
Previous message: Scott Branden: "[PATCH] mmc: sdhci: add quirk for ACMD23 broken"
In reply to: Pranith Kumar: "[PATCH] tinification: Make SRCU optional by using CONFIG_SRCU"
Next in thread: Lai Jiangshan: "Re: [PATCH] tinification: Make SRCU optional by using CONFIG_SRCU"
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