Re: [PATCH] checkpatch: Add a --strict test for structs with bool member definitions

[Joe Perches]

On Thu, 2018-04-12 at 08:22 +0200, Julia Lawall wrote:
> On Wed, 11 Apr 2018, Joe Perches wrote:
> > On Wed, 2018-04-11 at 09:29 -0700, Andrew Morton wrote:
> > > We already have some 500 bools-in-structs
> > 
> > I got at least triple that only in include/
> > so I expect there are at probably an order
> > of magnitude more than 500 in the kernel.
> > 
> > I suppose some cocci script could count the
> > actual number of instances.  A regex can not.
> 
> I got 12667.

Could you please post the cocci script?

> I'm not sure to understand the issue.  Will using a bitfield help if there
> are no other bitfields in the structure?

IMO, not really.

The primary issue is described by Linus here:
https://lkml.org/lkml/2017/11/21/384

I personally do not find a significant issue with
uncontrolled sizes of bool in kernel structs as
all of the kernel structs are transitory and not
written out to storage.

I suppose bool bitfields are also OK, but for the
RMW required.

Using unsigned int :1 bitfield instead of bool :1
has the negative of truncation so that the uint
has to be set with !! instead of a simple assign.