linux-kernel - Re: [RFC PATCH 1/7] audit: don't needlessly reset valid wait time

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Message-ID: <CAHC9VhTJhVEEPSr3tmx9WSjGU_BD_cxqqLt9qg4LdhCeG0sd8g@mail.gmail.com>
Date:	Thu, 5 Nov 2015 10:17:37 -0500
From:	Paul Moore <paul@...l-moore.com>
To:	Richard Guy Briggs <rgb@...hat.com>
Cc:	linux-audit@...hat.com, linux-kernel@...r.kernel.org,
	v.rathor@...il.com
Subject: Re: [RFC PATCH 1/7] audit: don't needlessly reset valid wait time

On Wed, Nov 4, 2015 at 10:13 PM, Richard Guy Briggs <rgb@...hat.com> wrote:
> On 15/11/04, Paul Moore wrote:
>> On Thursday, October 22, 2015 02:53:14 PM Richard Guy Briggs wrote:
>> > After auditd has recovered from an overflowed queue, the first process
>> > that doesn't use reserves to make it through the queue checks should
>> > reset the audit backlog wait time to the configured value.  After that,
>> > there is no need to keep resetting it.
>> >
>> > Signed-off-by: Richard Guy Briggs <rgb@...hat.com>
>> > ---
>> >  kernel/audit.c |    2 +-
>> >  1 files changed, 1 insertions(+), 1 deletions(-)
>> >
>> > diff --git a/kernel/audit.c b/kernel/audit.c
>> > index a72ad37..daefd81 100644
>> > --- a/kernel/audit.c
>> > +++ b/kernel/audit.c
>> > @@ -1403,7 +1403,7 @@ struct audit_buffer *audit_log_start(struct
>> > audit_context *ctx, gfp_t gfp_mask, return NULL;
>> >     }
>> >
>> > -   if (!reserve)
>> > +   if (!reserve && !audit_backlog_wait_time)
>> >             audit_backlog_wait_time = audit_backlog_wait_time_master;
>> >
>> >     ab = audit_buffer_alloc(ctx, gfp_mask, type);
>>
>> This looks fine to me, I'm going to add it to audit#next-queue.
>>
>> Also, can you think of a good reason why "audit_backlog_wait_overflow" exists?
>> I'm going to replace it with the simple "audit_backlog_wait_time = 0;" unless
>> you can think of a solid reason not to do so.  It seems much more obvious and
>> readable to me.
>
> That goes back to ac4cec44, DWMW, July 2005.  Best answer I can come up
> with is that it labels magic values and puts them up front at the top of
> the file.

Yeah, I can see that from git blame, I was hoping for some thread I
may have missed.  Oh well, not terribly important.

> I'd suggest instead replacing it with a macro.  I don't have
> an significant objection to just assigning zero where you suggest.

If it weren't zero I would agree with you, magic numbers in general
are a bit scary.  However, in this particular case I don't consider
zero to be a magic number and its use seems pretty clear given the
context.

-- 
paul moore
www.paul-moore.com
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