Re: [PATCH v8 3/4] cgroups: allow a cgroup subsystem to reject a fork

From: Aleksa Sarai
Date: Thu Apr 02 2015 - 19:42:34 EST

Hello, Tejun.

>> +struct cgroup_fork_state {
>> + void *ss_state[CGROUP_SUBSYS_COUNT];
>> +};
> Can we collect the subsystems which require pre/post fork callbacks to
> the front in group_subsys.h and do do CGROUP_SUBSYS_FORK_COUNT (or
> whatever) instead? Then, we don't need all these subsys bitmasks
> either we can just test the index against that and be done with it.

I tried doing this and the kernel would refuse to boot. I believe it has
something to do with the ordering of early_init subsystems, but I'm not
entirely sure (this optimisation can be dealt with later [it's non-critical],
so IMO this should be done in a separate patchset [if at all]). Also, your
later comments would fix the subsys bitmask problem (we can just pass the
default %NULL), we don't even need to test the index.

Aleksa Sarai (cyphar)
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