Messages in this thread Patch in this message | | | Date | Fri, 24 Apr 2015 23:59:31 +1000 | Subject | Re: [PATCH v10 3/4] cgroups: allow a cgroup subsystem to reject a fork | From | Aleksa Sarai <> |
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Hey,
>> +#define CGROUP_PREFORK_COUNT 0 >> + >> static inline int cgroup_init_early(void) { return 0; } >> static inline int cgroup_init(void) { return 0; } >> static inline void cgroup_fork(struct task_struct *p) {} >> -static inline void cgroup_post_fork(struct task_struct *p) {} >> +static inline int cgroup_can_fork(struct task_struct *p, >> + void *s[CGROUP_PREFORK_COUNT]) >> +{ >> + return 0; >> +} > > Style consistency?
It's because it wraps. I can move it to be something like:
static inline int cgroup_can_fork(struct task_struct *p, void *s[CGROUP_PREFORK_COUNT]) { return 0; }
If you like.
>> @@ -2078,6 +2084,18 @@ static void cgroup_task_migrate(struct cgroup *old_cgrp, >> list_move_tail(&tsk->cg_list, &new_cset->mg_tasks); >> >> /* >> + * We detach from the old_cset subsystems here. We must do this >> + * before we drop the refcount for old_cset, in order to make sure >> + * that nobody frees it underneath us. >> + */ >> + for_each_e_css(css, i, old_cgrp) { >> + struct cgroup_subsys_state *old_css = old_cset->subsys[i]; >> + >> + if (old_css->ss->detach) >> + old_css->ss->detach(old_css, tsk); >> + } > > I don't get this. What can ->detach do that ->can_attach cannot?
->detach signifies that a task is being migrated away from a cgroup. On second thought, we could just use task_css() on each task in the tset to figure out what the cgroup the task is being migrated away from is and just uncharge that inside ->can_attach.
On the same point, are all the tasks in a tset passed to ->can_attach guaranteed to have the same css? Or do I have to uncharge each one individually?
-- Aleksa Sarai (cyphar) www.cyphar.com
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