linux-toradex.git/include/linux/cgroup.h, branch tegra-10.11.4

cgroup: Remove call to synchronize_rcu in cgroup_attach_task

2010-12-18T01:01:51+00:00

synchronize_rcu can be very expensive, averaging 100 ms in
some cases.  In cgroup_attach_task, it is used to prevent
a task->cgroups pointer dereferenced in an RCU read side
critical section from being invalidated, by delaying the
call to put_css_set until after an RCU grace period.

To avoid the call to synchronize_rcu, make the put_css_set
call rcu-safe by moving the deletion of the css_set links
into free_css_set_work, scheduled by the rcu callback
free_css_set_rcu.

The decrement of the cgroup refcount is no longer
synchronous with the call to put_css_set, which can result
in the cgroup refcount staying positive after the last call
to cgroup_attach_task returns.  To allow the cgroup to be
deleted with cgroup_rmdir synchronously after
cgroup_attach_task, have rmdir check the refcount of all
associated css_sets.  If cgroup_rmdir is called on a cgroup
for which the css_sets all have refcount zero but the
cgroup refcount is nonzero, reuse the rmdir waitqueue to
block the rmdir until free_css_set_work is called.

Signed-off-by: Colin Cross

cgroup: Set CGRP_RELEASABLE when adding to a cgroup

2010-12-18T01:01:49+00:00

Changes the meaning of CGRP_RELEASABLE to be set on any cgroup
that has ever had a task or cgroup in it, or had css_get called
on it.  The bit is set in cgroup_attach_task, cgroup_create,
and __css_get.  It is not necessary to set the bit in
cgroup_fork, as the task is either in the root cgroup, in
which can never be released, or the task it was forked from
already set the bit in croup_attach_task.

Signed-off-by: Colin Cross

cgroups: fix API thinko

2010-09-10T01:57:23+00:00

Add cgroup_attach_task_all()

The existing cgroup_attach_task_current_cg() API is called by a thread to
attach another thread to all of its cgroups; this is unsuitable for cases
where a privileged task wants to attach itself to the cgroups of a less
privileged one, since the call must be made from the context of the target
task.

This patch adds a more generic cgroup_attach_task_all() API that allows
both the source task and to-be-moved task to be specified.
cgroup_attach_task_current_cg() becomes a specialization of the more
generic new function.

[menage@google.com: rewrote changelog]
[akpm@linux-foundation.org: address reviewer comments]
Signed-off-by: Michael S. Tsirkin 
Tested-by: Alex Williamson 
Acked-by: Paul Menage 
Cc: Li Zefan 
Cc: Ben Blum 
Cc: Sridhar Samudrala 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6

2010-08-04T18:47:58+00:00

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6: (1443 commits)
  phy/marvell: add 88ec048 support
  igb: Program MDICNFG register prior to PHY init
  e1000e: correct MAC-PHY interconnect register offset for 82579
  hso: Add new product ID
  can: Add driver for esd CAN-USB/2 device
  l2tp: fix export of header file for userspace
  can-raw: Fix skb_orphan_try handling
  Revert "net: remove zap_completion_queue"
  net: cleanup inclusion
  phy/marvell: add 88e1121 interface mode support
  u32: negative offset fix
  net: Fix a typo from "dev" to "ndev"
  igb: Use irq_synchronize per vector when using MSI-X
  ixgbevf: fix null pointer dereference due to filter being set for VLAN 0
  e1000e: Fix irq_synchronize in MSI-X case
  e1000e: register pm_qos request on hardware activation
  ip_fragment: fix subtracting PPPOE_SES_HLEN from mtu twice
  net: Add getsockopt support for TCP thin-streams
  cxgb4: update driver version
  cxgb4: add new PCI IDs
  ...

Manually fix up conflicts in:
 - drivers/net/e1000e/netdev.c: due to pm_qos registration
   infrastructure changes
 - drivers/net/phy/marvell.c: conflict between adding 88ec048 support
   and cleaning up the IDs
 - drivers/net/wireless/ipw2x00/ipw2100.c: trivial ipw2100_pm_qos_req
   conflict (registration change vs marking it static)

cgroups: Add an API to attach a task to current task's cgroup

2010-07-28T12:45:12+00:00

Add a new kernel API to attach a task to current task's cgroup
in all the active hierarchies.

Signed-off-by: Sridhar Samudrala 
Signed-off-by: Michael S. Tsirkin 
Reviewed-by: Paul Menage 
Acked-by: Li Zefan

sched: Fix PROVE_RCU vs cpu_cgroup

2010-06-08T16:44:04+00:00

PROVE_RCU has a few issues with the cpu_cgroup because the scheduler
typically holds rq->lock around the css rcu derefs but the generic
cgroup code doesn't (and can't) know about that lock.

Provide means to add extra checks to the css dereference and use that
in the scheduler to annotate its users.

The addition of rq->lock to these checks is correct because the
cgroup_subsys::attach() method takes the rq->lock for each task it
moves, therefore by holding that lock, we ensure the task is pinned to
the current cgroup and the RCU derefence is valid.

That leaves one genuine race in __sched_setscheduler() where we used
task_group() without holding any of the required locks and thus raced
with the cgroup code. Solve this by moving the check under the
appropriate lock.

Signed-off-by: Peter Zijlstra 
Cc: "Paul E. McKenney" 
LKML-Reference: 
Signed-off-by: Ingo Molnar

cgroups: make cftype.unregister_event() void-returning

2010-05-27T16:12:44+00:00

Since we are unable to handle an error returned by
cftype.unregister_event() properly, let's make the callback
void-returning.

mem_cgroup_unregister_event() has been rewritten to be a "never fail"
function.  On mem_cgroup_usage_register_event() we save old buffer for
thresholds array and reuse it in mem_cgroup_usage_unregister_event() to
avoid allocation.

Signed-off-by: Kirill A. Shutemov 
Acked-by: KAMEZAWA Hiroyuki 
Cc: Phil Carmody 
Cc: Balbir Singh 
Cc: Daisuke Nishimura 
Cc: Paul Menage 
Cc: Li Zefan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cgroup: Check task_lock in task_subsys_state()

2010-05-04T16:25:02+00:00

Expand task_subsys_state()'s rcu_dereference_check() to include the full
locking rule as documented in Documentation/cgroups/cgroups.txt by adding
a check for task->alloc_lock being held.

This fixes an RCU false positive when resuming from suspend. The warning
comes from freezer cgroup in cgroup_freezing_or_frozen().

Signed-off-by: Li Zefan 
Acked-by: Matt Helsley 
Signed-off-by: Paul E. McKenney

cgroups: remove events before destroying subsystem state objects

2010-03-12T23:52:37+00:00

Events should be removed after rmdir of cgroup directory, but before
destroying subsystem state objects.  Let's take reference to cgroup
directory dentry to do that.

Signed-off-by: Kirill A. Shutemov 
Acked-by: KAMEZAWA Hiroyuki 
Cc: Paul Menage 
Acked-by: Li Zefan 
Cc: Balbir Singh 
Cc: Pavel Emelyanov 
Cc: Dan Malek 
Cc: Daisuke Nishimura 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cgroup: implement eventfd-based generic API for notifications

2010-03-12T23:52:37+00:00

This patchset introduces eventfd-based API for notifications in cgroups
and implements memory notifications on top of it.

It uses statistics in memory controler to track memory usage.

Output of time(1) on building kernel on tmpfs:

Root cgroup before changes:
	make -j2  506.37 user 60.93s system 193% cpu 4:52.77 total
Non-root cgroup before changes:
	make -j2  507.14 user 62.66s system 193% cpu 4:54.74 total
Root cgroup after changes (0 thresholds):
	make -j2  507.13 user 62.20s system 193% cpu 4:53.55 total
Non-root cgroup after changes (0 thresholds):
	make -j2  507.70 user 64.20s system 193% cpu 4:55.70 total
Root cgroup after changes (1 thresholds, never crossed):
	make -j2  506.97 user 62.20s system 193% cpu 4:53.90 total
Non-root cgroup after changes (1 thresholds, never crossed):
	make -j2  507.55 user 64.08s system 193% cpu 4:55.63 total

This patch:

Introduce the write-only file "cgroup.event_control" in every cgroup.

To register new notification handler you need:
- create an eventfd;
- open a control file to be monitored. Callbacks register_event() and
  unregister_event() must be defined for the control file;
- write "  " to cgroup.event_control.
  Interpretation of args is defined by control file implementation;

eventfd will be woken up by control file implementation or when the
cgroup is removed.

To unregister notification handler just close eventfd.

If you need notification functionality for a control file you have to
implement callbacks register_event() and unregister_event() in the
struct cftype.

[kamezawa.hiroyu@jp.fujitsu.com: Kconfig fix]
Signed-off-by: Kirill A. Shutemov 
Reviewed-by: KAMEZAWA Hiroyuki 
Paul Menage 
Cc: Li Zefan 
Cc: Balbir Singh 
Cc: Pavel Emelyanov 
Cc: Dan Malek 
Cc: Vladislav Buzov 
Cc: Daisuke Nishimura 
Cc: Alexander Shishkin 
Cc: Davide Libenzi 
Signed-off-by: KAMEZAWA Hiroyuki 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds