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SubjectRe: [PATCH v3 5/7] gpio: Add GPIO Aggregator/Repeater driver
Hi Eugeniu,

On Tue, Dec 3, 2019 at 11:51 AM Eugeniu Rosca <roscaeugeniu@gmail.com> wrote:
> On Wed, Nov 27, 2019 at 09:42:51AM +0100, Geert Uytterhoeven wrote:
> > +static int gpio_aggregator_probe(struct platform_device *pdev)
> > +{
> > + struct device *dev = &pdev->dev;
> > + struct gpio_desc **descs;
> > + struct gpiochip_fwd *fwd;
> > + int i, n;
>
> FWIW/FTR, doing some blind creation and deletion of gpio aggregator
> chips [1] on R-Car H3ULCB overnight, kmemleak reported once [2]. Not
> sure this is something 100% reproducible.
>
> [1] while true; do \
> echo e6055400.gpio 12,13 > /sys/bus/platform/drivers/gpio-aggregator/new_device; \
> echo gpio-aggregator.0 > /sys/bus/platform/drivers/gpio-aggregator/delete_device; \
> done
>
> [2] unreferenced object 0xffff0006d2c2e000 (size 128):
> comm "kworker/3:1", pid 55, jiffies 4294676978 (age 38546.676s)
> hex dump (first 32 bytes):
> 00 d9 d2 d3 06 00 ff ff 0c 00 e0 0f ff ff ff ff ................
> 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> backtrace:
> [<00000000a8e18c13>] slab_post_alloc_hook+0x8c/0x94
> [<000000006f419a4f>] __kmalloc+0x170/0x218
> [<0000000060d185ea>] kobj_map+0x78/0x1c0
> [<00000000c96645f3>] cdev_add+0x68/0x94
> [<00000000a7a5a8ac>] cdev_device_add+0x74/0x90
> [<00000000497871d3>] gpiochip_setup_dev+0x84/0x1f0
> [<00000000b993f95f>] gpiochip_add_data_with_key+0xbcc/0x11f0
> [<00000000fd728c0e>] devm_gpiochip_add_data+0x60/0xa8
> [<00000000442e34c1>] gpio_aggregator_probe+0x210/0x3c8
> [<00000000076e13fb>] platform_drv_probe+0x70/0xe4
> [<00000000de84b58b>] really_probe+0x2d8/0x434
> [<00000000c95c9784>] driver_probe_device+0x15c/0x16c
> [<00000000afb7dd4f>] __device_attach_driver+0xdc/0x120
> [<00000000efa40cae>] bus_for_each_drv+0x12c/0x154
> [<00000000c149acef>] __device_attach+0x148/0x1e0
> [<00000000a74fd158>] device_initial_probe+0x24/0x30

This is the allocation of the GPIO character device, which is allocated
in response to the creation of the GPIO chip, from .probe().
As that is done using devm_gpiochip_add_data(), the chardev should be
deallocated automatically by devm_gpio_chip_release() when
platform_device_unregister() is called.

Weird...

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds

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