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

From: Andrew Morton <akpm@linux-foundation.org>
To: Joe Perches <joe@perches.com>
Cc: Andy Whitcroft <apw@canonical.com>, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH] checkpatch: check for function calls with struct or union on stack
Date: Thu, 26 Jul 2018 12:25:33 -0700	[thread overview]
Message-ID: <20180726122533.104f6eea950853ef50ebc680@linux-foundation.org> (raw)
In-Reply-To: <1236369d28b2f1f5389ff652c4eb89e699e6481e.camel@perches.com>

On Thu, 26 Jul 2018 11:27:50 -0700 Joe Perches <joe@perches.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.