linux-kernel - Re: [PATCH v2 2/2] kernel-trace: Less calls for iput() in create_trace

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Date:	Sun, 16 Nov 2014 20:34:59 +0100 (CET)
From:	Julia Lawall <julia.lawall@...6.fr>
To:	Steven Rostedt <rostedt@...dmis.org>
cc:	SF Markus Elfring <elfring@...rs.sourceforge.net>,
	Ingo Molnar <mingo@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>,
	kernel-janitors@...r.kernel.org, Coccinelle <cocci@...teme.lip6.fr>
Subject: Re: [PATCH v2 2/2] kernel-trace: Less calls for iput() in
 create_trace_uprobe() after error detection

On Sun, 16 Nov 2014, Steven Rostedt wrote:

> On Sun, 16 Nov 2014 20:22:22 +0100
> SF Markus Elfring <elfring@...rs.sourceforge.net> wrote:
>
> > From: Markus Elfring <elfring@...rs.sourceforge.net>
> > Date: Sun, 16 Nov 2014 19:49:39 +0100
> >
> > The iput() function was called in three cases by the create_trace_uprobe()
> > function during error handling even if the passed variable contained still
> > a null pointer. This implementation detail could be improved by the
> > introduction of another jump label.
>
> The first patch is fine, and the only reason is to save the few bytes
> that the branch check might take. It's in a path that is unlikely to be
> hit so it is not a performance issue at all.
>
> This patch is useless. I rather not apply any patch than to create
> another jump that skips over the freeing of iput() just because we know
> inode is null. That's why we had the if (inode) in the first place.
>
> So Nack on this patch and I'll contemplate applying the first one. I
> probably will as it seems rather harmless.

I wuold have thought that one could have just returned, like in the cases
above...  But maybe the printed message is useful.

julia
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