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SubjectRe: [PATCH v4 1/2] IMA: Define workqueue for early boot "key" measurements
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On Fri, 2019-12-13 at 09:18 -0800, Lakshmi Ramasubramanian wrote:

> +/*
> + * ima_process_queued_keys() - process keys queued for measurement
> + *
> + * This function sets ima_process_keys to true and processes queued keys.
> + * From here on keys will be processed right away (not queued).
> + */
> +void ima_process_queued_keys(void)
> +{
> + struct ima_key_entry *entry, *tmp;
> + LIST_HEAD(temp_ima_keys);
> + bool process = false;
> +
> + if (ima_process_keys)
> + return;
> +
> + /*
> + * To avoid holding the mutex when processing queued keys,
> + * transfer the queued keys with the mutex held to a temp list,
> + * release the mutex, and then process the queued keys from
> + * the temp list.
> + *
> + * Since ima_process_keys is set to true, any new key will be
> + * processed immediately and not be queued.
> + */
> + INIT_LIST_HEAD(&temp_ima_keys);
> +
> + mutex_lock(&ima_keys_mutex);
> +
> + if (!ima_process_keys) {
> + ima_process_keys = true;

Thank you for moving the initialization here.  The comment is now
valid and the following code is now guaranteed to execute just once.

> +
> + if (!list_empty(&ima_keys)) {
> + list_for_each_entry_safe(entry, tmp, &ima_keys, list)
> + list_move_tail(&entry->list, &temp_ima_keys);
> + process = true;
> + }
> + }
> +
> + mutex_unlock(&ima_keys_mutex);
> +
> + if (!process)
> + return;

The new changes - checking if the list is empty and this test - are
unnecessary, as you implied earlier.

Mimi

> +
> + list_for_each_entry_safe(entry, tmp, &temp_ima_keys, list) {
> + process_buffer_measurement(entry->payload, entry->payload_len,
> + entry->keyring_name, KEY_CHECK, 0,
> + entry->keyring_name);
> + list_del(&entry->list);
> + ima_free_key_entry(entry);
> + }
> +}
> +
> /**
> * ima_post_key_create_or_update - measure asymmetric keys
> * @keyring: keyring to which the key is linked to

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