linux-kernel - Re: [driver-core PATCH v5 5/9] driver core: Establish clear order of operations for deferred probe and remove

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Date:   Thu, 08 Nov 2018 15:42:19 -0800
From:   Bart Van Assche <bvanassche@....org>
To:     Joe Perches <joe@...ches.com>,
        Alexander Duyck <alexander.h.duyck@...ux.intel.com>,
        linux-kernel@...r.kernel.org, gregkh@...uxfoundation.org
Cc:     linux-nvdimm@...ts.01.org, tj@...nel.org,
        akpm@...ux-foundation.org, linux-pm@...r.kernel.org,
        jiangshanlai@...il.com, rafael@...nel.org, len.brown@...el.com,
        pavel@....cz, zwisler@...nel.org, dan.j.williams@...el.com,
        dave.jiang@...el.com
Subject: Re: [driver-core PATCH v5 5/9] driver core: Establish clear order
 of operations for deferred probe and remove

On Tue, 2018-11-06 at 17:34 -0800, Joe Perches wrote:
> On Tue, 2018-11-06 at 15:48 -0800, Bart Van Assche wrote:
> > On Mon, 2018-11-05 at 13:12 -0800, Alexander Duyck wrote:
> > > One change I made in addition is I replaced the use of "bool X:1" to define
> > > the bitfield to a "u8 X:1" setup in order to resolve some checkpatch
> > > warnings.
> > 
> > Please use "bool X:1" instead of "u8 X:1". I think it was a bad idea to make
> > checkpatch complain about "bool X:1" since "bool X:1" should only be avoided
> > in structures for which alignment must be architecture-independent. For struct
> > device it is fine if member alignment differs per architecture. Additionally,
> > changing "bool X:1" into "u8 X:1" will reduce performance on architectures that
> > cannot do byte addressing.
> 
> I generally agree.  But the checkpatch warning _could_
> be useful in those cases where alignment should be
> architecture-independent.
> 
> Any suggestion on how to improve the message?

It would be great if a heuristic could be developed that recognizes structs
for which the data layout must be architecture independent. If such a
heuristic could be developed it could be used to only display warn about
"bool X:n" for such structures.

Bart.