From: Joe Perches <joe@perches.com>
To: David Miller <davem@davemloft.net>
Cc: thierry.reding@gmail.com, hkallweit1@gmail.com, andrew@lunn.ch,
nic_swsd@realtek.com, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 2/2] r8169: Avoid pointer aliasing
Date: Tue, 05 Feb 2019 11:19:04 -0800 [thread overview]
Message-ID: <143a8f022c73c71f170eb04dc0b763f9ae83f6b5.camel@perches.com> (raw)
In-Reply-To: <20190205.111404.1429981997134153696.davem@davemloft.net>
On Tue, 2019-02-05 at 11:14 -0800, David Miller wrote:
> From: Joe Perches <joe@perches.com>
> Date: Tue, 05 Feb 2019 10:42:54 -0800
>
> > On Mon, 2019-02-04 at 19:20 -0800, David Miller wrote:
> >> From: Thierry Reding <thierry.reding@gmail.com>
> >> Date: Mon, 4 Feb 2019 17:42:13 +0100
> >>
> >> > @@ -7316,7 +7325,7 @@ static int rtl_get_ether_clk(struct rtl8169_private *tp)
> >> > static int rtl_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
> >> > {
> >> > const struct rtl_cfg_info *cfg = rtl_cfg_infos + ent->driver_data;
> >> > - u8 mac_addr[ETH_ALEN] __aligned(4) = {};
> >> > + u8 mac_addr[ETH_ALEN] = {};
> >> > struct rtl8169_private *tp;
> >>
> >> I agree with Heiner, you have to provide at least 2 byte alignment for this
> >> buffer due to the reasons he stated.
> >
> > It's declared after a pointer so it is already is 2 byte aligned.
> >
> > A lot of drivers wouldn't work otherwise.
>
> That's assuming a lot about what the compiler will do when nit allocates
> local variables to the stack.
It's also assuming what a compiler will do when
it defines a struct.
> I want it _explicit_.
Your choice, but there are a _lot_ of existing uses
and I think requiring it is as senseless as requiring
void * arithmetic to be cast to char * as gcc and
clang already do not add padding after a pointer.
next prev parent reply other threads:[~2019-02-05 19:19 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-04 16:42 [PATCH v2 1/2] r8169: Load MAC address from device tree if present Thierry Reding
2019-02-04 16:42 ` [PATCH v2 2/2] r8169: Avoid pointer aliasing Thierry Reding
2019-02-04 16:59 ` Andrew Lunn
2019-02-04 18:44 ` Heiner Kallweit
2019-02-05 3:20 ` David Miller
2019-02-05 18:42 ` Joe Perches
2019-02-05 19:14 ` David Miller
2019-02-05 19:19 ` Joe Perches [this message]
2019-02-06 7:25 ` Michal Kubecek
2019-02-05 20:04 ` Eric Dumazet
2019-02-05 20:18 ` Joe Perches
2019-02-05 20:23 ` Eric Dumazet
2019-02-05 20:23 ` Heiner Kallweit
2019-02-04 19:30 ` [PATCH v2 1/2] r8169: Load MAC address from device tree if present Heiner Kallweit
2019-02-06 2:27 [PATCH v2 2/2] r8169: Avoid pointer aliasing Paul Zimmerman
2019-02-06 2:52 ` Joe Perches
2019-02-06 3:25 ` Paul Zimmerman
2019-02-06 3:49 ` Joe Perches
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=143a8f022c73c71f170eb04dc0b763f9ae83f6b5.camel@perches.com \
--to=joe@perches.com \
--cc=andrew@lunn.ch \
--cc=davem@davemloft.net \
--cc=hkallweit1@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=netdev@vger.kernel.org \
--cc=nic_swsd@realtek.com \
--cc=thierry.reding@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).