2024-01-29 13:11:45

by Chen Jun

Subject: [PATCH] irqchip/mbigen: Fix incorrect null pointer check

bus_get_dev_root(&platform_bus_type) always returns NULL.
This makes mbigen_of_create_domain always return -ENODEV.

Fixes: fea087fc291b ("irqchip/mbigen: move to use bus_get_dev_root()")
Signed-off-by: Chen Jun <[email protected]>
---
drivers/irqchip/irq-mbigen.c | 8 +-------
1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/drivers/irqchip/irq-mbigen.c b/drivers/irqchip/irq-mbigen.c
index 5101a3fb11df..58881d313979 100644
--- a/drivers/irqchip/irq-mbigen.c
+++ b/drivers/irqchip/irq-mbigen.c
@@ -235,22 +235,17 @@ static const struct irq_domain_ops mbigen_domain_ops = {
static int mbigen_of_create_domain(struct platform_device *pdev,
struct mbigen_device *mgn_chip)
{
- struct device *parent;
struct platform_device *child;
struct irq_domain *domain;
struct device_node *np;
u32 num_pins;
int ret = 0;

- parent = bus_get_dev_root(&platform_bus_type);
- if (!parent)
- return -ENODEV;
-
for_each_child_of_node(pdev->dev.of_node, np) {
if (!of_property_read_bool(np, "interrupt-controller"))
continue;

- child = of_platform_device_create(np, NULL, parent);
+ child = of_platform_device_create(np, NULL, NULL);
if (!child) {
ret = -ENOMEM;
break;
@@ -273,7 +268,6 @@ static int mbigen_of_create_domain(struct platform_device *pdev,
}
}

- put_device(parent);
if (ret)
of_node_put(np);

--
2.17.1

2024-02-13 10:12:27

by Thomas Gleixner

Subject: Re: [PATCH] irqchip/mbigen: Fix incorrect null pointer check

On Mon, Jan 29 2024 at 21:00, Chen Jun wrote:
> bus_get_dev_root(&platform_bus_type) always returns NULL.
> This makes mbigen_of_create_domain always return -ENODEV.
>
> Fixes: fea087fc291b ("irqchip/mbigen: move to use bus_get_dev_root()")

Amazing that it took 9 month to figure that out ...

2024-02-13 10:17:07

by Thomas Gleixner

Subject: Re: [PATCH] irqchip/mbigen: Fix incorrect null pointer check

On Mon, Jan 29 2024 at 21:00, Chen Jun wrote:

That's not about an incorrect NULL pointer check. That's about using a
function which is guaranteed to return NULL on your platform, no?

> bus_get_dev_root(&platform_bus_type) always returns NULL.

Lacks an explanation why this always returns NULL.

Thanks

tglx

2024-02-18 03:13:24

by Chen Jun

Subject: Re: [PATCH] irqchip/mbigen: Fix incorrect null pointer check

$B:_(B 2024/2/13 18:09, Thomas Gleixner $B<LF;(B:
> On Mon, Jan 29 2024 at 21:00, Chen Jun wrote:
>
> That's not about an incorrect NULL pointer check. That's about using a
> function which is guaranteed to return NULL on your platform, no?
>
>> bus_get_dev_root(&platform_bus_type) always returns NULL.
>
> Lacks an explanation why this always returns NULL.
>

Thank you for the reply.

bus_get_dev_root returns sp->dev_root set in subsys_register.
And subsys_register is not called by platform_bus_init.

So, for platform_bus_type, bus_get_dev_root always returns NULL.

> Thanks
>
> tglx
>
>

2024-02-18 19:58:55

by Thomas Gleixner

Subject: Re: [PATCH] irqchip/mbigen: Fix incorrect null pointer check

On Sun, Feb 18 2024 at 03:13, chenjun (AM) wrote:
> 在 2024/2/13 18:09, Thomas Gleixner 写道:
>> On Mon, Jan 29 2024 at 21:00, Chen Jun wrote:
>>
>> That's not about an incorrect NULL pointer check. That's about using a
>> function which is guaranteed to return NULL on your platform, no?
>>
>>> bus_get_dev_root(&platform_bus_type) always returns NULL.
>>
>> Lacks an explanation why this always returns NULL.
>>
>
> Thank you for the reply.
>
> bus_get_dev_root returns sp->dev_root set in subsys_register.
> And subsys_register is not called by platform_bus_init.
>
> So, for platform_bus_type, bus_get_dev_root always returns NULL.

Please add this information to the change log.

Thanks,

tglx