[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH v2 05/17] xen/cpupool: switch cpupool list to normal list interface
On 01.12.2020 09:21, Juergen Gross wrote: > @@ -260,23 +257,42 @@ static struct cpupool *cpupool_create( > > spin_lock(&cpupool_lock); > > - for_each_cpupool(q) > + if ( poolid != CPUPOOLID_NONE ) > { > - last = (*q)->cpupool_id; > - if ( (poolid != CPUPOOLID_NONE) && (last >= poolid) ) > - break; > + q = __cpupool_find_by_id(poolid, false); > + if ( !q ) > + list_add_tail(&c->list, &cpupool_list); > + else > + { > + list_add_tail(&c->list, &q->list); > + if ( q->cpupool_id == poolid ) > + { > + *perr = -EEXIST; > + goto err; > + } You bail _after_ having added the new entry to the list? > + } > + > + c->cpupool_id = poolid; > } > - if ( *q != NULL ) > + else > { > - if ( (*q)->cpupool_id == poolid ) > + /* Cpupool 0 is created with specified id at boot and never removed. > */ > + ASSERT(!list_empty(&cpupool_list)); > + > + q = list_last_entry(&cpupool_list, struct cpupool, list); > + /* In case of wrap search for first free id. */ > + if ( q->cpupool_id == CPUPOOLID_NONE - 1 ) > { > - *perr = -EEXIST; > - goto err; > + list_for_each_entry(q, &cpupool_list, list) > + if ( q->cpupool_id + 1 != list_next_entry(q, > list)->cpupool_id ) > + break; > } > - c->next = *q; > + > + list_add(&c->list, &q->list); > + > + c->cpupool_id = q->cpupool_id + 1; What guarantees that you managed to find an unused ID, other than at current CPU speeds it taking too long to create 4 billion pools? Since you're doing this under lock, wouldn't it help anyway to have a global helper variable pointing at the lowest pool followed by an unused ID? Jan
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