From mboxrd@z Thu Jan  1 00:00:00 1970
From: Waiman Long <longman@redhat.com>
Date: Sun, 15 Mar 2020 22:01:51 +0000
Subject: Re: [PATCH v3 3/3] KEYS: Use kvmalloc() to better handle large buffer allocation
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References: <20200313152102.1707-1-longman@redhat.com>
 <20200313152102.1707-4-longman@redhat.com>
 <20200313164306.GA907@sol.localdomain>
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In-Reply-To: <20200315215253.GG224162@linux.intel.com>
To: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: Eric Biggers <ebiggers@kernel.org>, David Howells <dhowells@redhat.com>, James Morris <jmorris@namei.org>, "Serge E. Hallyn" <serge@hallyn.com>, Mimi Zohar <zohar@linux.ibm.com>, keyrings@vger.kernel.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, linux-integrity@vger.kernel.org, Sumit Garg <sumit.garg@linaro.org>, Jerry Snitselaar <jsnitsel@redhat.com>, Roberto Sassu <roberto.sassu@huawei.com>, Chris von Recklinghausen <crecklin@redhat.com>

On 3/15/20 5:52 PM, Jarkko Sakkinen wrote:
> On Fri, Mar 13, 2020 at 01:49:57PM -0400, Waiman Long wrote:
>>>>  			if (!tmpbuf || unlikely(ret > tmpbuflen)) {
>>>>  				if (unlikely(tmpbuf))
>>>> -					kzfree(tmpbuf);
>>>> +					__kvzfree(tmpbuf, tmpbuflen);
>>> Both kzfree() and __kvzfree() handle a NULL pointer, so there's no need for the
>>> NULL check first.
>>>
>> I would like to keep this one because of the unlikely annotation.
> What (measurable) gain does it bring anyway?

It is not a performance issue. I just want to indicate that the need to
free should not happen at all. It match the unlikely tag in the if
condition above.

Cheers,
Longman