On Mon, Apr 10, 2023 at 11:16 AM Naresh Kamboju
<naresh.kamboju@xxxxxxxxxx> wrote:
(...)
> Anders performed bisection on this problem.
> The bisection have been poing to this commit log,
> first bad commit: [24c94060fc9b4e0f19e6e018869db46db21d6bc7]
> gpiolib: ensure that fwnode is properly set
I don't think this is the real issue.
(...)
> # 2. Module load error tests
> # 2.1 gpio overflow
(...)
> [ 88.900984] Freed in software_node_release+0xdc/0x108 age=34 cpu=1 pid=683
> [ 88.907899] __kmem_cache_free+0x2a4/0x2e0
> [ 88.912024] kfree+0xc0/0x1a0
> [ 88.915015] software_node_release+0xdc/0x108
> [ 88.919402] kobject_put+0xb0/0x220
> [ 88.922919] software_node_notify_remove+0x98/0xe8
> [ 88.927741] device_del+0x184/0x380
> [ 88.931259] platform_device_del.part.0+0x24/0xa8
> [ 88.935995] platform_device_unregister+0x30/0x50
I think the refcount is wrong on the fwnode.
The chip is allocated with devm_gpiochip_add_data() which will not call
gpiochip_remove() until all references are removed by calling
devm_gpio_chip_release().
Add a pr_info() devm_gpio_chip_release() in drivers/gpio/gpiolib-devres.c
and see if the callback is even called. I think this could be the
problem: if that isn't cleaned up, there will be dangling references.
diff --git a/drivers/gpio/gpiolib-devres.c b/drivers/gpio/gpiolib-devres.c
index fe9ce6b19f15..30a0622210d7 100644
--- a/drivers/gpio/gpiolib-devres.c
+++ b/drivers/gpio/gpiolib-devres.c
@@ -394,6 +394,7 @@ static void devm_gpio_chip_release(void *data)
{
struct gpio_chip *gc = data;
+ pr_info("GPIOCHIP %s WAS REMOVED BY DEVRES\n", gc->label);
gpiochip_remove(gc);
}
If this isn't working we need to figure out what is holding a reference to
the gpiochip.
I don't know how the references to the gpiochip fwnode is supposed to
drop to zero though? I didn't work with mockup much ...
What I could think of is that maybe the mockup driver need a .shutdown()
callback to forcibly call gpiochip_remove(), and in that case it should
be wrapped in a non-existining devm_gpiochip_remove() since devres
is used to register it.
Bartosz will know better though! I am pretty sure he has this working
flawlessly so the tests must be doing something weird which is leaving
references around.
Yours,
Linus Walleij
