>> @@ -1561,8 +1561,10 @@ static int cpuset_write_resmask(struct cgroup *cgrp, struct cftype *cft,
>> return -ENODEV;
>>
>> trialcs = alloc_trial_cpuset(cs);
>> - if (!trialcs)
>> + if (!trialcs) {
>> + cgroup_unlock();
>> return -ENOMEM;
>> + }
>>
>> switch (cft->private) {
>> case FILE_CPULIST:
>
> It would be better to avoid multiple returns - it leads to more
> maintainable code and often shorter code:
>
I have no strong opinion on this.
> --- a/kernel/cpuset.c~cpuset-add-a-missing-unlock-in-cpuset_write_resmask-fix
> +++ a/kernel/cpuset.c
> @@ -1562,8 +1562,8 @@ static int cpuset_write_resmask(struct c
>
> trialcs = alloc_trial_cpuset(cs);
> if (!trialcs) {
> - cgroup_unlock();
> - return -ENOMEM;
> + retval = -ENOMEM;
> + goto out;
> }
>
> switch (cft->private) {
> @@ -1579,6 +1579,7 @@ static int cpuset_write_resmask(struct c
> }
>
> free_trial_cpuset(trialcs);
> +out:
> cgroup_unlock();
> return retval;
> }
> _
>
> also, alloc_trial_cpuset() is a fairly slow-looking function.
> cpuset_write_resmask() could run alloc_trial_cpuset() before running
> cgroup_lock_live_group(), thereby reducing lock hold times.
>
Nope. alloc_trial_cpuset() will read 'cs', so it must be protected by
the lock.
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