From: Mimi Zohar <zohar@linux.ibm.com>
To: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>,
linux-integrity@vger.kernel.org
Cc: eric.snowberg@oracle.com, dhowells@redhat.com,
mathew.j.martineau@linux.intel.com, matthewgarrett@google.com,
sashal@kernel.org, jamorris@linux.microsoft.com,
linux-kernel@vger.kernel.org, keyrings@vger.kernel.org
Subject: Re: [PATCH v3 1/2] IMA: Define workqueue for early boot "key" measurements
Date: Thu, 12 Dec 2019 21:32:57 -0500 [thread overview]
Message-ID: <1576204377.4579.206.camel@linux.ibm.com> (raw)
In-Reply-To: <6e0dad33-66f9-4807-d08d-ff30396cec5e@linux.microsoft.com>
On Thu, 2019-12-12 at 17:59 -0800, Lakshmi Ramasubramanian wrote:
> 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().
The first test prevents taking the mutex unnecessarily.
Mimi
> +void ima_process_queued_keys(void)
> +{
> + struct ima_key_entry *entry, *tmp;
> + LIST_HEAD(temp_ima_keys);
> +
> + if (ima_process_keys)
> + return;
>
> thanks,
> -lakshmi
next prev parent reply other threads:[~2019-12-13 2:33 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-13 0:42 [PATCH v3 0/2] IMA: Deferred measurement of keys Lakshmi Ramasubramanian
2019-12-13 0:42 ` [PATCH v3 1/2] IMA: Define workqueue for early boot "key" measurements Lakshmi Ramasubramanian
2019-12-13 1:55 ` Mimi Zohar
2019-12-13 1:59 ` Lakshmi Ramasubramanian
2019-12-13 2:32 ` Mimi Zohar [this message]
2019-12-13 2:59 ` Lakshmi Ramasubramanian
2019-12-13 13:06 ` Mimi Zohar
2019-12-13 15:51 ` Lakshmi Ramasubramanian
2019-12-15 12:44 ` Mimi Zohar
2019-12-13 0:42 ` [PATCH v3 2/2] IMA: Call workqueue functions to measure queued keys Lakshmi Ramasubramanian
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