From: Bartosz Golaszewski <brgl@kernel.org>
To: Rosen Penev <rosenp@gmail.com>
Cc: Kees Cook <kees@kernel.org>,
linux-gpio@vger.kernel.org,
Bamvor Jian Zhang <bamv2005@gmail.com>,
Linus Walleij <linusw@kernel.org>,
"Gustavo A. R. Silva" <gustavoars@kernel.org>,
open list <linux-kernel@vger.kernel.org>,
"open list:KERNEL HARDENING (not covered by other
areas):Keyword:b__counted_by(_le|_be)?b"
<linux-hardening@vger.kernel.org>,
Bartosz Golaszewski <brgl@kernel.org>
Subject: Re: [PATCH] gpio: mockup: allocate lines with main struct
Date: Tue, 24 Mar 2026 02:16:41 -0700 [thread overview]
Message-ID: <CAMRc=Me2RLj-vvCVNho9CPYVwsQHypC_KvKHJWkLyj=rMkfx2w@mail.gmail.com> (raw)
In-Reply-To: <CAKxU2N9KdziPen9-_gfe0UZjyuMTOsbb583aeF3=kqm22rGieA@mail.gmail.com>
On Mon, 23 Mar 2026 17:43:00 +0100, Rosen Penev <rosenp@gmail.com> said:
> On Mon, Mar 23, 2026 at 3:00 AM Bartosz Golaszewski <brgl@kernel.org> wrote:
>>
>> On Sat, Mar 21, 2026 at 12:00 AM Rosen Penev <rosenp@gmail.com> wrote:
>> >
>> > >
>> > > static int gpio_mockup_probe(struct platform_device *pdev)
>> > > {
>> > > ...
>> > > u16 ngpio;
>> > > ...
>> > > rv = device_property_read_u16(dev, "nr-gpios", &ngpio);
>> > > ...
>> > > gc->ngpio = ngpio;
>> > > ...
>> > > chip->lines = devm_kcalloc(dev, gc->ngpio,
>> > > sizeof(*chip->lines), GFP_KERNEL);
>> > >
>> > > But this begs the question: why add nr_lines when ngpio is already part
>> > > of the struct:
>> > Maintainers for some inexplicable reason want an extra variable for
>> > __counted_by works.
>>
>> I believe what Kees means here is: you can use ngpio for __counted_by() like so:
>>
>> __counted_by(gc.ngpio)
> __counted_by doesn't support nested variables like that.
>
> drivers/gpio/gpio-mockup.c:59:61: error: ‘gc’ undeclared here (not in
> a function)
> 59 | struct gpio_mockup_line_status lines[] __counted_by(gc.ngpio);
The following spin on your patch builds fine for me:
diff --git a/drivers/gpio/gpio-mockup.c b/drivers/gpio/gpio-mockup.c
index a7d69f3835c1e..9427ab8c45f73 100644
--- a/drivers/gpio/gpio-mockup.c
+++ b/drivers/gpio/gpio-mockup.c
@@ -52,10 +52,10 @@ struct gpio_mockup_line_status {
struct gpio_mockup_chip {
struct gpio_chip gc;
- struct gpio_mockup_line_status *lines;
struct irq_domain *irq_sim_domain;
struct dentry *dbg_dir;
struct mutex lock;
+ struct gpio_mockup_line_status lines[] __counted_by(gc.ngpio);
};
struct gpio_mockup_dbgfs_private {
@@ -436,15 +436,16 @@ static int gpio_mockup_probe(struct platform_device *pdev)
if (rv)
name = dev_name(dev);
- chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
+ chip = devm_kzalloc(dev, struct_size(chip, lines, ngpio), GFP_KERNEL);
if (!chip)
return -ENOMEM;
- mutex_init(&chip->lock);
-
gc = &chip->gc;
- gc->base = base;
gc->ngpio = ngpio;
+ gc->base = base;
+
+ mutex_init(&chip->lock);
+
gc->label = name;
gc->owner = THIS_MODULE;
gc->parent = dev;
@@ -460,11 +461,6 @@ static int gpio_mockup_probe(struct platform_device *pdev)
gc->request = gpio_mockup_request;
gc->free = gpio_mockup_free;
- chip->lines = devm_kcalloc(dev, gc->ngpio,
- sizeof(*chip->lines), GFP_KERNEL);
- if (!chip->lines)
- return -ENOMEM;
-
for (i = 0; i < gc->ngpio; i++)
chip->lines[i].dir = GPIO_LINE_DIRECTION_IN;
Bart
next prev parent reply other threads:[~2026-03-24 9:16 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-19 0:05 [PATCH] gpio: mockup: allocate lines with main struct Rosen Penev
2026-03-20 13:28 ` Linus Walleij
2026-03-20 18:10 ` Kees Cook
2026-03-20 23:00 ` Rosen Penev
2026-03-23 10:00 ` Bartosz Golaszewski
2026-03-23 16:43 ` Rosen Penev
2026-03-24 9:16 ` Bartosz Golaszewski [this message]
2026-03-24 15:51 ` Rosen Penev
2026-03-24 15:54 ` Bartosz Golaszewski
2026-03-24 15:56 ` Rosen Penev
2026-03-24 17:16 ` Bartosz Golaszewski
2026-03-24 18:25 ` Rosen Penev
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='CAMRc=Me2RLj-vvCVNho9CPYVwsQHypC_KvKHJWkLyj=rMkfx2w@mail.gmail.com' \
--to=brgl@kernel.org \
--cc=bamv2005@gmail.com \
--cc=gustavoars@kernel.org \
--cc=kees@kernel.org \
--cc=linusw@kernel.org \
--cc=linux-gpio@vger.kernel.org \
--cc=linux-hardening@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=rosenp@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 read-only IMAP folder(s) and NNTP newsgroup(s).