YAMAMOTO Takashi wrote:
>> @@ -36,10 +37,26 @@ int res_counter_charge(struct res_counter *counter, unsigned long val)
>> {
>> int ret;
>> unsigned long flags;
>> + struct res_counter *c, *unroll_c;
>> +
>> + local_irq_save(flags);
>> + for (c = counter; c != NULL; c = c->parent) {
>> + spin_lock(&c->lock);
>> + ret = res_counter_charge_locked(c, val);
>> + spin_unlock(&c->lock);
>> + if (ret < 0)
>> + goto unroll;
>> + }
>> + local_irq_restore(flags);
>> + return 0;
>>
>> - spin_lock_irqsave(&counter->lock, flags);
>> - ret = res_counter_charge_locked(counter, val);
>> - spin_unlock_irqrestore(&counter->lock, flags);
>> +unroll:
>> + for (unroll_c = counter; unroll_c != c; unroll_c = unroll_c->parent) {
>> + spin_lock(&unroll_c->lock);
>> + res_counter_uncharge_locked(unroll_c, val);
>> + spin_unlock(&unroll_c->lock);
>> + }
>> + local_irq_restore(flags);
>> return ret;
>> }
>
> what prevents the topology (in particular, ->parent pointers) from
> changing behind us?
The res_counter client must provide this. Currently cgroup subsystem does this.
> YAMAMOTO Takashi
>
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