linux-kernel - Re: [RFC PATCH] checkpatch: check for function calls with struct or union on stack

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Message-Id: <20180726122533.104f6eea950853ef50ebc680@linux-foundation.org>
Date:   Thu, 26 Jul 2018 12:25:33 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Joe Perches <joe@...ches.com>
Cc:     Andy Whitcroft <apw@...onical.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH] checkpatch: check for function calls with struct or
 union on stack

On Thu, 26 Jul 2018 11:27:50 -0700 Joe Perches <joe@...ches.com> wrote:

> I was cc'd on a patch where structs were used on stack instead
> of using pointers to the structs.

"passed by value" is a good term for this practice.

  This can cause defects when
> the calling function modifies the stack struct instead of the

     "called"

> calling function's struct.
> 
> Possible patch below, but it may be overkill for the number of
> instances
> where this is actually an issue.
> 
> Thoughts?

Seems worthwhile.

> There are what seems to be some false positives for a few of the
> .h files in include/linux/... where the false positives are for
> very small structs where the indirection via a pointer might be
> slower than than the stack use.
> 
> For instance: (some duplicates removed)

I'll give it a spin, see how noisy it is.