[v2] firmware: qcom: scm: Fix incorrect of_node_put call in scm_init

Message ID 1512555692-14439-1-git-send-email-lollivier@baylibre.com
State New
Headers show
Series
  • [v2] firmware: qcom: scm: Fix incorrect of_node_put call in scm_init
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Commit Message

Loys Ollivier Dec. 6, 2017, 10:21 a.m.
When using other platform architectures, in the init of the qcom_scm
driver, of_node_put is called on /firmware if no qcom dt is found.
This results in a kernel error: Bad of_node_put() on /firmware.

The call to of_node_put from the qcom_scm init is unnecessary as
of_find_matching_node is calling it automatically.

Remove this of_node_put().

Fixes: d0f6fa7ba2d6 ("firmware: qcom: scm: Convert SCM to platform driver")
Signed-off-by: Loys Ollivier <lollivier@baylibre.com>

---
Change since v1, remove the curly brackets as if statement becomes a
one liner.

 drivers/firmware/qcom_scm.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

-- 
2.7.4

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Comments

Jerome Forissier Dec. 7, 2017, 8:42 a.m. | #1
On 12/06/2017 09:06 PM, Stephen Boyd wrote:
> On 12/06, Loys Ollivier wrote:

>> When using other platform architectures, in the init of the qcom_scm

>> driver, of_node_put is called on /firmware if no qcom dt is found.

>> This results in a kernel error: Bad of_node_put() on /firmware.

>>

>> The call to of_node_put from the qcom_scm init is unnecessary as

>> of_find_matching_node is calling it automatically.

>>

>> Remove this of_node_put().

>>

>> Fixes: d0f6fa7ba2d6 ("firmware: qcom: scm: Convert SCM to platform driver")

>> Signed-off-by: Loys Ollivier <lollivier@baylibre.com>

>> ---

> 

> This still looks wrong. Especially if of_find_matching_node() is

> going to look for siblings of the /firmware node for the

> compatible string for scm device. Why do we check at all? Can't

> we just delete this and let of_platform_populate() take care of

> it? BTW, OP-TEE driver seems to have a similar problem.


https://lkml.org/lkml/2017/11/29/230
		
> 

> ---8<----

> 

> diff --git a/drivers/firmware/qcom_scm.c b/drivers/firmware/qcom_scm.c

> index af4c75217ea6..440d8f796faa 100644

> --- a/drivers/firmware/qcom_scm.c

> +++ b/drivers/firmware/qcom_scm.c

> @@ -626,23 +626,11 @@ static int __init qcom_scm_init(void)

>  	int ret;

>  

>  	fw_np = of_find_node_by_name(NULL, "firmware");

> -

>  	if (!fw_np)

> -		return -ENODEV;

> -

> -	np = of_find_matching_node(fw_np, qcom_scm_dt_match);

> -

> -	if (!np) {

> -		of_node_put(fw_np);

> -		return -ENODEV;

> -	}

> -

> -	of_node_put(np);

> +		return 0;

>  

>  	ret = of_platform_populate(fw_np, qcom_scm_dt_match, NULL, NULL);

> -

>  	of_node_put(fw_np);

> -

>  	if (ret)

>  		return ret;

>  

> 

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Stephen Boyd Dec. 8, 2017, 5:04 p.m. | #2
On 12/07, Loys Ollivier wrote:
> 

> 

> On 07/12/2017 09:42, Jerome Forissier wrote:

> > 

> > 

> > On 12/06/2017 09:06 PM, Stephen Boyd wrote:

> >> On 12/06, Loys Ollivier wrote:

> >>> When using other platform architectures, in the init of the qcom_scm

> >>> driver, of_node_put is called on /firmware if no qcom dt is found.

> >>> This results in a kernel error: Bad of_node_put() on /firmware.

> >>>

> >>> The call to of_node_put from the qcom_scm init is unnecessary as

> >>> of_find_matching_node is calling it automatically.

> >>>

> >>> Remove this of_node_put().

> >>>

> >>> Fixes: d0f6fa7ba2d6 ("firmware: qcom: scm: Convert SCM to platform driver")

> >>> Signed-off-by: Loys Ollivier <lollivier@baylibre.com>

> >>> ---

> >>

> >> This still looks wrong. Especially if of_find_matching_node() is

> >> going to look for siblings of the /firmware node for the

> >> compatible string for scm device. Why do we check at all? Can't

> >> we just delete this and let of_platform_populate() take care of

> >> it? BTW, OP-TEE driver seems to have a similar problem.

> > 

> > https://lkml.org/lkml/2017/11/29/230

> >

> Well, the patch I sent is a fix for a specific bug I am encountering.

> I tested the patch and it solves my problem. Stephen, your changes looks

> good but it's a change in the driver's behavior. Maybe it could be

> another patch ?


Sure. But there's another of_node_put(fw_np) in this function, so
why isn't that also removed? Assuming of_find_matching_node() is
calling of_node_put() on what's passed in, then the node is going
to get put twice in the "working" case.

Andy?

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Loys Ollivier Dec. 12, 2017, 3:35 p.m. | #3
On 08/12/2017 18:04, Stephen Boyd wrote:
> On 12/07, Loys Ollivier wrote:

>>

>>

>> On 07/12/2017 09:42, Jerome Forissier wrote:

>>>

>>>

>>> On 12/06/2017 09:06 PM, Stephen Boyd wrote:

>>>> On 12/06, Loys Ollivier wrote:

>>>>> When using other platform architectures, in the init of the qcom_scm

>>>>> driver, of_node_put is called on /firmware if no qcom dt is found.

>>>>> This results in a kernel error: Bad of_node_put() on /firmware.

>>>>>

>>>>> The call to of_node_put from the qcom_scm init is unnecessary as

>>>>> of_find_matching_node is calling it automatically.

>>>>>

>>>>> Remove this of_node_put().

>>>>>

>>>>> Fixes: d0f6fa7ba2d6 ("firmware: qcom: scm: Convert SCM to platform driver")

>>>>> Signed-off-by: Loys Ollivier <lollivier@baylibre.com>

>>>>> ---

>>>>

>>>> This still looks wrong. Especially if of_find_matching_node() is

>>>> going to look for siblings of the /firmware node for the

>>>> compatible string for scm device. Why do we check at all? Can't

>>>> we just delete this and let of_platform_populate() take care of

>>>> it? BTW, OP-TEE driver seems to have a similar problem.

>>>

>>> https://lkml.org/lkml/2017/11/29/230

>>>

>> Well, the patch I sent is a fix for a specific bug I am encountering.

>> I tested the patch and it solves my problem. Stephen, your changes looks

>> good but it's a change in the driver's behavior. Maybe it could be

>> another patch ?

> 

> Sure. But there's another of_node_put(fw_np) in this function, so

> why isn't that also removed? Assuming of_find_matching_node() is

> calling of_node_put() on what's passed in, then the node is going

> to get put twice in the "working" case.

> 

> Andy?

>

Agreed, I had a look and this second call to of_node_put(fw_np) seem to
be unnecessary as well. Unfortunately I can't test your suggestion as I
am using another platform arch. I am just testing that this driver does
not break my arch.
I can submit a v3 removing this of_node_put as well if you want.
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Patch

diff --git a/drivers/firmware/qcom_scm.c b/drivers/firmware/qcom_scm.c
index af4c75217ea6..5beb6a6adcf6 100644
--- a/drivers/firmware/qcom_scm.c
+++ b/drivers/firmware/qcom_scm.c
@@ -632,10 +632,8 @@  static int __init qcom_scm_init(void)
 
 	np = of_find_matching_node(fw_np, qcom_scm_dt_match);
 
-	if (!np) {
-		of_node_put(fw_np);
+	if (!np)
 		return -ENODEV;
-	}
 
 	of_node_put(np);