On Sat 03-11-12 01:38:33, Tejun Heo wrote: > Introduce FREEZING_SELF and FREEZING_PARENT and make FREEZING OR of > the two flags. This is to prepare for full hierarchy support. > > freezer_apply_date() is updated such that it can handle setting and > clearing of both flags. The two flags are also exposed to userland > via read-only files self_freezing and parent_freezing. > > Other than the added cgroupfs files, this patch doesn't introduce any > behavior change. OK, I can imagine that this might be useful to find the first parent group that needs to be thawed to unfreeze the group I am interested in. Could you also update Documentation/cgroups/freezer-subsystem.txt to clarify the intended usage? Minor nit. Same as mentioned in the previous patch freezer_apply_state should get enum freezer_state_flags state parameter. > Signed-off-by: Tejun Heo <tj@xxxxxxxxxx> Reviewed-by: Michal Hocko <mhocko@xxxxxxx> > --- > kernel/cgroup_freezer.c | 55 ++++++++++++++++++++++++++++++++++++++++++------- > 1 file changed, 47 insertions(+), 8 deletions(-) > > diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c > index e76aa9f..b8ad93c 100644 > --- a/kernel/cgroup_freezer.c > +++ b/kernel/cgroup_freezer.c > @@ -23,8 +23,12 @@ > #include <linux/seq_file.h> > > enum freezer_state_flags { > - CGROUP_FREEZING = (1 << 1), /* this freezer is freezing */ > + CGROUP_FREEZING_SELF = (1 << 1), /* this freezer is freezing */ > + CGROUP_FREEZING_PARENT = (1 << 2), /* the parent freezer is freezing */ > CGROUP_FROZEN = (1 << 3), /* this and its descendants frozen */ > + > + /* mask for all FREEZING flags */ > + CGROUP_FREEZING = CGROUP_FREEZING_SELF | CGROUP_FREEZING_PARENT, > }; > > struct freezer { > @@ -245,8 +249,13 @@ static void unfreeze_cgroup(struct freezer *freezer) > * freezer_apply_state - apply state change to a single cgroup_freezer > * @freezer: freezer to apply state change to > * @freeze: whether to freeze or unfreeze > + * @state: CGROUP_FREEZING_* flag to set or clear > + * > + * Set or clear @state on @cgroup according to @freeze, and perform > + * freezing or thawing as necessary. > */ > -static void freezer_apply_state(struct freezer *freezer, bool freeze) > +static void freezer_apply_state(struct freezer *freezer, bool freeze, > + unsigned int state) > { > /* also synchronizes against task migration, see freezer_attach() */ > lockdep_assert_held(&freezer->lock); > @@ -254,13 +263,19 @@ static void freezer_apply_state(struct freezer *freezer, bool freeze) > if (freeze) { > if (!(freezer->state & CGROUP_FREEZING)) > atomic_inc(&system_freezing_cnt); > - freezer->state |= CGROUP_FREEZING; > + freezer->state |= state; > freeze_cgroup(freezer); > } else { > - if (freezer->state & CGROUP_FREEZING) > - atomic_dec(&system_freezing_cnt); > - freezer->state &= ~(CGROUP_FREEZING | CGROUP_FROZEN); > - unfreeze_cgroup(freezer); > + bool was_freezing = freezer->state & CGROUP_FREEZING; > + > + freezer->state &= ~state; > + > + if (!(freezer->state & CGROUP_FREEZING)) { > + if (was_freezing) > + atomic_dec(&system_freezing_cnt); > + freezer->state &= ~CGROUP_FROZEN; > + unfreeze_cgroup(freezer); > + } > } > } > > @@ -275,7 +290,7 @@ static void freezer_change_state(struct freezer *freezer, bool freeze) > { > /* update @freezer */ > spin_lock_irq(&freezer->lock); > - freezer_apply_state(freezer, freeze); > + freezer_apply_state(freezer, freeze, CGROUP_FREEZING_SELF); > spin_unlock_irq(&freezer->lock); > } > > @@ -295,6 +310,20 @@ static int freezer_write(struct cgroup *cgroup, struct cftype *cft, > return 0; > } > > +static u64 freezer_self_freezing_read(struct cgroup *cgroup, struct cftype *cft) > +{ > + struct freezer *freezer = cgroup_freezer(cgroup); > + > + return (bool)(freezer->state & CGROUP_FREEZING_SELF); > +} > + > +static u64 freezer_parent_freezing_read(struct cgroup *cgroup, struct cftype *cft) > +{ > + struct freezer *freezer = cgroup_freezer(cgroup); > + > + return (bool)(freezer->state & CGROUP_FREEZING_PARENT); > +} > + > static struct cftype files[] = { > { > .name = "state", > @@ -302,6 +331,16 @@ static struct cftype files[] = { > .read_seq_string = freezer_read, > .write_string = freezer_write, > }, > + { > + .name = "self_freezing", > + .flags = CFTYPE_NOT_ON_ROOT, > + .read_u64 = freezer_self_freezing_read, > + }, > + { > + .name = "parent_freezing", > + .flags = CFTYPE_NOT_ON_ROOT, > + .read_u64 = freezer_parent_freezing_read, > + }, > { } /* terminate */ > }; > > -- > 1.7.11.7 > -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html