On Fri, 14 Jul 2006, [EMAIL PROTECTED] wrote:
> +int cipso_v4_doi_add(struct cipso_v4_doi *doi_def)
> +{
> + if (doi_def == NULL || doi_def->doi == CIPSO_V4_DOI_UNKNOWN)
> + return -EINVAL;
> +
> + doi_def->valid = 1;
> + INIT_RCU_HEAD(&doi_def->rcu);
> + INIT_LIST_HEAD(&doi_def->dom_list);
> +
> + rcu_read_lock();
> + if (cipso_v4_doi_search(doi_def->doi) != NULL) {
> + rcu_read_unlock();
> + return -EEXIST;
> + }
> + spin_lock(&cipso_v4_doi_list_lock);
> + list_add_tail_rcu(&doi_def->list, &cipso_v4_doi_list);
> + spin_unlock(&cipso_v4_doi_list_lock);
> + rcu_read_unlock();
> +
> + return 0;
> +}
This is racy in that you can end up with duplicate entries in the list
between rcu_read_lock() and spin_lock().
You need to perform the search a second time under the spin_lock() as a
slow path to verify that an entry wasn't added, before adding a new one.
- James
James Morris
<[EMAIL PROTECTED]>
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