Thread (48 messages) 48 messages, 7 authors, 2025-05-13

Re: [PATCH v5 08/12] gpio: aggregator: export symbols of the GPIO forwarder library

From: Thomas Richard <thomas.richard@bootlin.com>
Date: 2025-05-12 14:30:20
Also in: linux-hardening, lkml

On 5/12/25 16:11, Andy Shevchenko wrote:
On Mon, May 12, 2025 at 04:08:35PM +0200, Thomas Richard wrote:
quoted
On 5/9/25 11:07, Geert Uytterhoeven wrote:
quoted
On Tue, 6 May 2025 at 17:21, Thomas Richard [off-list ref] wrote:
...
quoted
quoted
quoted
+int gpio_fwd_set_config(struct gpio_chip *chip, unsigned int offset,
+                       unsigned long config);
+
+int gpio_fwd_to_irq(struct gpio_chip *chip, unsigned int offset);
I would expect all of these to take gpiochip_fwd pointers instead of
gpio_chip pointers.  What prevents you from passing a gpio_chip pointer
that does not correspond to a gpiochip_fwd object, causing a crash?
Indeed nothing prevents from passing gpio_chip pointer which does not
correspond to a gpiochip_fwd object.
And it is also a bit weird to pass a gpiochip_fwd pointer in some cases
(for example gpio_fwd_gpio_add()) and a gpio_chip in other cases.

I can keep GPIO operations as is, and create exported wrappers which
take a gpiochip_fwd pointer as parameter, for example:

int gpiochip_fwd_get_multiple(struct gpiochip_fwd *fwd,
			      unsigned long *mask,
			      unsigned long *bits)
{
	struct gpio_chip *gc = gpiochip_fwd_get_gpiochip(fwd);

	return gpio_fwd_get_multiple_locked(chip, mask, bits);
}
EXPORT_SYMBOL_NS_GPL(gpiochip_fwd_get_multiple, "GPIO_FORWARDER");

So exported functions are gpiochip_fwd_*().
Sounds good for me. Let's wait for Geert's opinoin on this.
Regarding Geert's comment for patch 9/12, an other proposal for naming:
As mentioned above, exported functions gpiochip_fwd_*() take a
gpiochip_fwd as parameter.

But for all functions corresponding to a GPIO operation add the gpio
word, and for functions to add/remove GPIO descriptor add the desc word:

devm_gpiochip_fwd_alloc()
gpiochip_fwd_register()

gpiochip_fwd_desc_add()
gpiochip_fwd_desc_free()

gpiochip_fwd_get_gpiochip()
gpiochip_fwd_get_data()

gpiochip_fwd_gpio_request()
gpiochip_fwd_gpio_get_direction()
gpiochip_fwd_gpio_direction_input()
gpiochip_fwd_gpio_direction_output()
gpiochip_fwd_gpio_get()
gpiochip_fwd_gpio_set()
gpiochip_fwd_gpio_set_multiple()
gpiochip_fwd_gpio_get_multiple()
gpiochip_fwd_gpio_set_config()
gpiochip_fwd_gpio_to_irq()

Regards,

Thomas
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