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: Cedric Le Goater <clg@fr.ibm.com>
Signed-off-by: Matt Helsley <matthltc@us.ibm.com>
Acked-by: Serge E. Hallyn <serue@us.ibm.com>
Tested-by: Matt Helsley <matthltc@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

22 files changed, 41 insertions, 0 deletions

diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig
index a0f642b..6110197 100644
--- a/arch/alpha/Kconfig
+++ b/arch/alpha/Kconfig
@@ -70,6 +70,7 @@ config AUTO_IRQ_AFFINITY
 	default y
 
 source "init/Kconfig"
+source "kernel/Kconfig.freezer"
 
 
 menu "System setup"
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 4853f9d..df39d20 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -192,6 +192,8 @@ config VECTORS_BASE
 
 source "init/Kconfig"
 
+source "kernel/Kconfig.freezer"
+
 menu "System Type"
 
 choice
diff --git a/arch/avr32/Kconfig b/arch/avr32/Kconfig
index 7c239a9..33a5b29 100644
--- a/arch/avr32/Kconfig
+++ b/arch/avr32/Kconfig
@@ -72,6 +72,8 @@ config GENERIC_BUG
 
 source "init/Kconfig"
 
+source "kernel/Kconfig.freezer"
+
 menu "System Type and features"
 
 source "kernel/time/Kconfig"
diff --git a/arch/blackfin/Kconfig b/arch/blackfin/Kconfig
index 8102c79..29e71ed 100644
--- a/arch/blackfin/Kconfig
+++ b/arch/blackfin/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"
diff --git a/arch/cris/Kconfig b/arch/cris/Kconfig
index 9389d38..07335e7 100644
--- a/arch/cris/Kconfig
+++ b/arch/cris/Kconfig
@@ -62,6 +62,8 @@ config HZ
 
 source "init/Kconfig"
 
+source "kernel/Kconfig.freezer"
+
 menu "General setup"
 
 source "fs/Kconfig.binfmt"
diff --git a/arch/frv/Kconfig b/arch/frv/Kconfig
index a5aac1b..9d1552a 100644
--- a/arch/frv/Kconfig
+++ b/arch/frv/Kconfig
@@ -66,6 +66,8 @@ mainmenu "Fujitsu FR-V Kernel Configuration"
 
 source "init/Kconfig"
 
+source "kernel/Kconfig.freezer"
+
 
 menu "Fujitsu FR-V system setup"
 
diff --git a/arch/h8300/Kconfig b/arch/h8300/Kconfig
index c796674..bd19954 100644
--- a/arch/h8300/Kconfig
+++ b/arch/h8300/Kconfig
@@ -90,6 +90,8 @@ config HZ
 
 source "init/Kconfig"
 
+source "kernel/Kconfig.freezer"
+
 source "arch/h8300/Kconfig.cpu"
 
 menu "Executable file formats"
diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig
index 3b7aa38..912c57d 100644
--- a/arch/ia64/Kconfig
+++ b/arch/ia64/Kconfig
@@ -7,6 +7,8 @@ mainmenu "IA-64 Linux Kernel Configuration"
 
 source "init/Kconfig"
 
+source "kernel/Kconfig.freezer"
+
 menu "Processor type and features"
 
 config IA64
diff --git a/arch/m32r/Kconfig b/arch/m32r/Kconfig
index 00289c1..dbaed4a 100644
--- a/arch/m32r/Kconfig
+++ b/arch/m32r/Kconfig
@@ -42,6 +42,8 @@ config HZ
 
 source "init/Kconfig"
 
+source "kernel/Kconfig.freezer"
+
 
 menu "Processor type and features"
 
diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
index 677c93a..836fb66 100644
--- a/arch/m68k/Kconfig
+++ b/arch/m68k/Kconfig
@@ -62,6 +62,8 @@ mainmenu "Linux/68k Kernel Configuration"
 
 source "init/Kconfig"
 
+source "kernel/Kconfig.freezer"
+
 menu "Platform dependent setup"
 
 config EISA
diff --git a/arch/m68knommu/Kconfig b/arch/m68knommu/Kconfig
index 0a89983..76b66fe 100644
--- a/arch/m68knommu/Kconfig
+++ b/arch/m68knommu/Kconfig
@@ -75,6 +75,8 @@ config NO_IOPORT
 
 source "init/Kconfig"
 
+source "kernel/Kconfig.freezer"
+
 menu "Processor type and features"
 
 choice
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index b905744..5f149b0 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -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
diff --git a/arch/mn10300/Kconfig b/arch/mn10300/Kconfig
index dd557c9..9a9f433 100644
--- a/arch/mn10300/Kconfig
+++ b/arch/mn10300/Kconfig
@@ -68,6 +68,8 @@ mainmenu "Matsushita MN10300/AM33 Kernel Configuration"
 
 source "init/Kconfig"
 
+source "kernel/Kconfig.freezer"
+
 
 menu "Matsushita MN10300 system setup"
 
diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
index 8313fcc..2bd1f6e 100644
--- a/arch/parisc/Kconfig
+++ b/arch/parisc/Kconfig
@@ -90,6 +90,8 @@ config ARCH_MAY_HAVE_PC_FDC
 
 source "init/Kconfig"
 
+source "kernel/Kconfig.freezer"
+
 
 menu "Processor type and features"
 
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 380baa1..9391199 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -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"
 
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index bc581d8..70b7645 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -78,6 +78,8 @@ config S390
 
 source "init/Kconfig"
 
+source "kernel/Kconfig.freezer"
+
 menu "Base setup"
 
 comment "Processor type and features"
diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index 5131d50..2ed5713 100644
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -106,6 +106,8 @@ config IO_TRAPPED
 
 source "init/Kconfig"
 
+source "kernel/Kconfig.freezer"
+
 menu "System type"
 
 #
diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index 97671da..e594559 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -37,6 +37,8 @@ config HZ
 
 source "init/Kconfig"
 
+source "kernel/Kconfig.freezer"
+
 menu "General machine setup"
 
 config SMP
diff --git a/arch/sparc64/Kconfig b/arch/sparc64/Kconfig
index 5446e2a..035b15a 100644
--- a/arch/sparc64/Kconfig
+++ b/arch/sparc64/Kconfig
@@ -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"
 
diff --git a/arch/um/Kconfig b/arch/um/Kconfig
index 6976812..393bccf 100644
--- a/arch/um/Kconfig
+++ b/arch/um/Kconfig
@@ -229,6 +229,8 @@ endmenu
 
 source "init/Kconfig"
 
+source "kernel/Kconfig.freezer"
+
 source "drivers/block/Kconfig"
 
 source "arch/um/Kconfig.char"
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index bd3c2c5..49349ba 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -193,6 +193,7 @@ config X86_TRAMPOLINE
 config KTIME_SCALAR
 	def_bool X86_32
 source "init/Kconfig"
+source "kernel/Kconfig.freezer"
 
 menu "Processor type and features"
 
diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig
index 02e417d..a213260 100644
--- a/arch/xtensa/Kconfig
+++ b/arch/xtensa/Kconfig
@@ -55,6 +55,7 @@ config HZ
 	default 100
 
 source "init/Kconfig"
+source "kernel/Kconfig.freezer"
 
 menu "Processor type and features"