From: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
To: Wei Liu <wei.liu@kernel.org>
Cc: Dexuan Cui <decui@microsoft.com>,
"Gustavo A. R. Silva" <gustavo@embeddedor.com>,
KY Srinivasan <kys@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
Stephen Hemminger <sthemmin@microsoft.com>,
Sasha Levin <sashal@kernel.org>,
Andrew Murray <amurray@thegoodpenguin.co.uk>,
Bjorn Helgaas <bhelgaas@google.com>,
"linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] PCI: hv: Replace zero-length array with flexible-array member
Date: Wed, 4 Mar 2020 18:06:35 +0000 [thread overview]
Message-ID: <20200304180635.GA21844@e121166-lin.cambridge.arm.com> (raw)
In-Reply-To: <20200304175509.dwhn63omfzewaukv@debian>
On Wed, Mar 04, 2020 at 05:55:09PM +0000, Wei Liu wrote:
> On Thu, Feb 13, 2020 at 03:43:40AM +0000, Dexuan Cui wrote:
> > > From: linux-hyperv-owner@vger.kernel.org
> > > <linux-hyperv-owner@vger.kernel.org> On Behalf Of Gustavo A. R. Silva
> > > Sent: Wednesday, February 12, 2020 4:51 PM
> > > ...
> > > The current codebase makes use of the zero-length array language
> > > extension to the C90 standard, but the preferred mechanism to declare
> > > variable-length types such as these ones is a flexible array member[1][2],
> > > introduced in C99:
> > >
> > > struct foo {
> > > int stuff;
> > > struct boo array[];
> > > };
> > >
> > > By making use of the mechanism above, we will get a compiler warning
> > > in case the flexible array does not occur last in the structure, which
> > > will help us prevent some kind of undefined behavior bugs from being
> > > inadvertently introduced[3] to the codebase from now on.
> > >
> > > Also, notice that, dynamic memory allocations won't be affected by
> > > this change:
> > >
> > > "Flexible array members have incomplete type, and so the sizeof operator
> > > may not be applied. As a quirk of the original implementation of
> > > zero-length arrays, sizeof evaluates to zero."[1]
> > >
> > > This issue was found with the help of Coccinelle.
> >
> > Looks good to me. Thanks, Gustavo!
> >
> > Reviewed-by: Dexuan Cui <decui@microsoft.com>
> >
>
> Lorenzo, will you be picking up this patch? It seems to me you've been
> handling patches to pci-hyperv.c. This patch is not yet in pci/hv branch
> in your repository.
>
> Let me know what you think.
I shall pick it up, I checked patchwork and it was erroneously
assigned to Bjorn, that's why I have not taken it yet.
Fixed now, apologies, I will merge it shortly.
Lorenzo
next prev parent reply other threads:[~2020-03-04 18:06 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-13 0:50 [PATCH] PCI: hv: Replace zero-length array with flexible-array member Gustavo A. R. Silva
2020-02-13 3:43 ` Dexuan Cui
2020-03-04 17:55 ` Wei Liu
2020-03-04 18:06 ` Lorenzo Pieralisi [this message]
2020-03-04 18:10 ` Wei Liu
2020-03-04 18:24 ` Gustavo A. R. Silva
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