From: "Michal Suchánek" <msuchanek@suse.de>
To: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: "Erhard F." <erhard_f@mailbox.org>,
"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE"
<devicetree@vger.kernel.org>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
Javier Martinez Canillas <javierm@redhat.com>,
open list <linux-kernel@vger.kernel.org>,
Rob Herring <robh+dt@kernel.org>,
Thomas Zimmermann <tzimmermann@suse.de>,
Frank Rowand <frowand.list@gmail.com>
Subject: Re: [PATCH v2] of: Fix of platform build on powerpc due to bad of disaply code
Date: Fri, 20 Jan 2023 13:10:55 +0100 [thread overview]
Message-ID: <20230120121055.GU16547@kitsune.suse.cz> (raw)
In-Reply-To: <20230119103446.GO16547@kitsune.suse.cz>
On Thu, Jan 19, 2023 at 11:34:46AM +0100, Michal Suchánek wrote:
> Hello,
>
> On Thu, Jan 19, 2023 at 10:24:07AM +0000, Christophe Leroy wrote:
> >
> >
> > Le 19/01/2023 à 10:53, Michal Suchanek a écrit :
> > > The commit 2d681d6a23a1 ("of: Make of framebuffer devices unique")
> > > breaks build because of wrong argument to snprintf. That certainly
> > > avoids the runtime error but is not the intended outcome.
> > >
> > > Also use standard device name format of-display.N for all created
> > > devices.
> > >
> > > Fixes: 2d681d6a23a1 ("of: Make of framebuffer devices unique")
> > > Signed-off-by: Michal Suchanek <msuchanek@suse.de>
> > > ---
> > > v2: Update the device name format
> > > ---
> > > drivers/of/platform.c | 12 ++++++++----
> > > 1 file changed, 8 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/drivers/of/platform.c b/drivers/of/platform.c
> > > index f2a5d679a324..8c1b1de22036 100644
> > > --- a/drivers/of/platform.c
> > > +++ b/drivers/of/platform.c
> > > @@ -525,7 +525,9 @@ static int __init of_platform_default_populate_init(void)
> > > if (IS_ENABLED(CONFIG_PPC)) {
> > > struct device_node *boot_display = NULL;
> > > struct platform_device *dev;
> > > - int display_number = 1;
> > > + int display_number = 0;
> > > + char buf[14];
> >
> > Can you declare that in the for block where it is used instead ?
>
> No, there are two for blocks.
>
> >
> > > + char *of_display_format = "of-display.%d";
> >
> > Should be const ?
>
> Yes, could be.
>
> >
> > > int ret;
> > >
> > > /* Check if we have a MacOS display without a node spec */
> > > @@ -556,7 +558,10 @@ static int __init of_platform_default_populate_init(void)
> > > if (!of_get_property(node, "linux,opened", NULL) ||
> > > !of_get_property(node, "linux,boot-display", NULL))
> > > continue;
> > > - dev = of_platform_device_create(node, "of-display", NULL);
> > > + ret = snprintf(buf, sizeof(buf), of_display_format, display_number++);
> > > + if (ret >= sizeof(buf))
> > > + continue;
> >
> >
> > Can you make buf big enough to avoid that ?
>
> It would be a bit fragile that way.
>
> The buffer would have to theoretically accomodate
> "of-display.-9223372036854775808", and any change to the format requires
> recalculating the length, by hand.
>
> Of course, the memory would run out way before allocating that many
> devices so it's kind of pointless to try and accomodate all possible
> device numbers.
>
> >
> > And by the way could it be called something else than 'buf' ?
> >
> > See exemple here :
> > https://elixir.bootlin.com/linux/v6.1/source/drivers/fsi/fsi-occ.c#L690
>
> Yes, that is quite possible. Nonetheless, just like 'ret' generic
> variable names also work.
And in fact judicious use of short generic variable names is more
readeable than naming all variables foobar_* as far as I am concerned.
Of course, YMMV.
Thanks
Michal
next prev parent reply other threads:[~2023-01-20 12:11 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-17 16:58 [PATCH] of: Make of framebuffer devices unique Michal Suchanek
2023-01-18 16:24 ` Rob Herring
2023-01-18 20:13 ` Erhard F.
2023-01-18 21:46 ` Michal Suchánek
2023-01-19 8:00 ` Thomas Zimmermann
2023-01-19 9:01 ` Michal Suchánek
2023-01-19 9:18 ` Thomas Zimmermann
2023-01-18 21:50 ` [PATCH] of: Fix of platform build on powerpc due to bad of disaply code Michal Suchanek
2023-01-19 9:53 ` [PATCH v2] " Michal Suchanek
2023-01-19 10:00 ` Thomas Zimmermann
2023-01-19 11:42 ` Erhard F.
[not found] ` <8a9f7ba5-37a4-0927-4ab2-d212f1b098a9@csgroup.eu>
2023-01-19 10:34 ` Michal Suchánek
2023-01-20 12:10 ` Michal Suchánek [this message]
2023-01-19 13:11 ` Thomas Zimmermann
2023-01-19 13:23 ` Michal Suchánek
2023-01-19 15:20 ` Thomas Zimmermann
2023-01-20 11:27 ` Michal Suchánek
2023-01-20 11:39 ` Thomas Zimmermann
2023-01-20 11:56 ` Michal Suchánek
2023-01-19 15:18 ` Rob Herring
2023-01-20 17:23 ` Rob Herring
2023-01-20 17:52 ` Michal Suchánek
2023-01-20 18:09 ` [PATCH v3] of: Make of framebuffer devices unique Michal Suchanek
2023-01-30 16:50 ` Rob Herring
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