linux-kernel - Re: [PATCH v3 1/2] IMA: Define workqueue for early boot "key" measurements

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Date:   Thu, 12 Dec 2019 17:59:11 -0800
From:   Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>
To:     Mimi Zohar <zohar@...ux.ibm.com>, linux-integrity@...r.kernel.org
Cc:     eric.snowberg@...cle.com, dhowells@...hat.com,
        mathew.j.martineau@...ux.intel.com, matthewgarrett@...gle.com,
        sashal@...nel.org, jamorris@...ux.microsoft.com,
        linux-kernel@...r.kernel.org, keyrings@...r.kernel.org
Subject: Re: [PATCH v3 1/2] IMA: Define workqueue for early boot "key"
 measurements

On 12/12/19 5:55 PM, Mimi Zohar 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);
>> +
>> +	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);
> 
> Don't you need a test here, before setting ima_process_keys?
> 
> 	if (ima_process_keys)
> 		return;
> 
> Mimi

That check is done before the comment - at the start of 
ima_process_queued_keys().

+void ima_process_queued_keys(void)
+{
+	struct ima_key_entry *entry, *tmp;
+	LIST_HEAD(temp_ima_keys);
+
+	if (ima_process_keys)
+		return;

thanks,
  -lakshmi