Commit dc52ddc0 authored by Matt Helsley's avatar Matt Helsley Committed by Linus Torvalds
Browse files

container freezer: implement freezer cgroup subsystem


This patch implements a new freezer subsystem in the control groups
framework.  It provides a way to stop and resume execution of all tasks in
a cgroup by writing in the cgroup filesystem.

The freezer subsystem in the container filesystem defines a file named
freezer.state.  Writing "FROZEN" to the state file will freeze all tasks
in the cgroup.  Subsequently writing "RUNNING" will unfreeze the tasks in
the cgroup.  Reading will return the current state.

* Examples of usage :

   # mkdir /containers/freezer
   # mount -t cgroup -ofreezer freezer  /containers
   # mkdir /containers/0
   # echo $some_pid > /containers/0/tasks

to get status of the freezer subsystem :

   # cat /containers/0/freezer.state
   RUNNING

to freeze all tasks in the container :

   # echo FROZEN > /containers/0/freezer.state
   # cat /containers/0/freezer.state
   FREEZING
   # cat /containers/0/freezer.state
   FROZEN

to unfreeze all tasks in the container :

   # echo RUNNING > /containers/0/freezer.state
   # cat /containers/0/freezer.state
   RUNNING

This is the basic mechanism which should do the right thing for user space
task in a simple scenario.

It's important to note that freezing can be incomplete.  In that case we
return EBUSY.  This means that some tasks in the cgroup are busy doing
something that prevents us from completely freezing the cgroup at this
time.  After EBUSY, the cgroup will remain partially frozen -- reflected
by freezer.state reporting "FREEZING" when read.  The state will remain
"FREEZING" until one of these things happens:

	1) Userspace cancels the freezing operation by writing "RUNNING" to
		the freezer.state file
	2) Userspace retries the freezing operation by writing "FROZEN" to
		the freezer.state file (writing "FREEZING" is not legal
		and returns EIO)
	3) The tasks that blocked the cgroup from entering the "FROZEN"
		state disappear from the cgroup's set of tasks.

[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: export thaw_process]
Signed-off-by: default avatarCedric Le Goater <clg@fr.ibm.com>
Signed-off-by: default avatarMatt Helsley <matthltc@us.ibm.com>
Acked-by: default avatarSerge E. Hallyn <serue@us.ibm.com>
Tested-by: default avatarMatt Helsley <matthltc@us.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 8174f150
......@@ -70,6 +70,7 @@ config AUTO_IRQ_AFFINITY
default y
source "init/Kconfig"
source "kernel/Kconfig.freezer"
menu "System setup"
......
......@@ -192,6 +192,8 @@ config VECTORS_BASE
source "init/Kconfig"
source "kernel/Kconfig.freezer"
menu "System Type"
choice
......
......@@ -72,6 +72,8 @@ config GENERIC_BUG
source "init/Kconfig"
source "kernel/Kconfig.freezer"
menu "System Type and features"
source "kernel/time/Kconfig"
......
......@@ -64,8 +64,11 @@ config HARDWARE_PM
depends on OPROFILE
source "init/Kconfig"
source "kernel/Kconfig.preempt"
source "kernel/Kconfig.freezer"
menu "Blackfin Processor Options"
comment "Processor and Board Settings"
......
......@@ -62,6 +62,8 @@ config HZ
source "init/Kconfig"
source "kernel/Kconfig.freezer"
menu "General setup"
source "fs/Kconfig.binfmt"
......
......@@ -66,6 +66,8 @@ mainmenu "Fujitsu FR-V Kernel Configuration"
source "init/Kconfig"
source "kernel/Kconfig.freezer"
menu "Fujitsu FR-V system setup"
......
......@@ -90,6 +90,8 @@ config HZ
source "init/Kconfig"
source "kernel/Kconfig.freezer"
source "arch/h8300/Kconfig.cpu"
menu "Executable file formats"
......
......@@ -7,6 +7,8 @@ mainmenu "IA-64 Linux Kernel Configuration"
source "init/Kconfig"
source "kernel/Kconfig.freezer"
menu "Processor type and features"
config IA64
......
......@@ -42,6 +42,8 @@ config HZ
source "init/Kconfig"
source "kernel/Kconfig.freezer"
menu "Processor type and features"
......
......@@ -62,6 +62,8 @@ mainmenu "Linux/68k Kernel Configuration"
source "init/Kconfig"
source "kernel/Kconfig.freezer"
menu "Platform dependent setup"
config EISA
......
......@@ -75,6 +75,8 @@ config NO_IOPORT
source "init/Kconfig"
source "kernel/Kconfig.freezer"
menu "Processor type and features"
choice
......
......@@ -1885,6 +1885,8 @@ config PROBE_INITRD_HEADER
add initrd or initramfs image to the kernel image.
Otherwise, say N.
source "kernel/Kconfig.freezer"
menu "Bus options (PCI, PCMCIA, EISA, ISA, TC)"
config HW_HAS_EISA
......
......@@ -68,6 +68,8 @@ mainmenu "Matsushita MN10300/AM33 Kernel Configuration"
source "init/Kconfig"
source "kernel/Kconfig.freezer"
menu "Matsushita MN10300 system setup"
......
......@@ -90,6 +90,8 @@ config ARCH_MAY_HAVE_PC_FDC
source "init/Kconfig"
source "kernel/Kconfig.freezer"
menu "Processor type and features"
......
......@@ -230,6 +230,8 @@ config PPC_OF_PLATFORM_PCI
source "init/Kconfig"
source "kernel/Kconfig.freezer"
source "arch/powerpc/sysdev/Kconfig"
source "arch/powerpc/platforms/Kconfig"
......
......@@ -78,6 +78,8 @@ config S390
source "init/Kconfig"
source "kernel/Kconfig.freezer"
menu "Base setup"
comment "Processor type and features"
......
......@@ -106,6 +106,8 @@ config IO_TRAPPED
source "init/Kconfig"
source "kernel/Kconfig.freezer"
menu "System type"
#
......
......@@ -37,6 +37,8 @@ config HZ
source "init/Kconfig"
source "kernel/Kconfig.freezer"
menu "General machine setup"
config SMP
......
......@@ -96,6 +96,7 @@ config GENERIC_HARDIRQS_NO__DO_IRQ
def_bool y
source "init/Kconfig"
source "kernel/Kconfig.freezer"
menu "Processor type and features"
......
......@@ -229,6 +229,8 @@ endmenu
source "init/Kconfig"
source "kernel/Kconfig.freezer"
source "drivers/block/Kconfig"
source "arch/um/Kconfig.char"
......
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