diff mbox series

ARM: s3c: irq-s3c24xx: Fix return value check for s3c24xx_init_intc()

Message ID 20210831095728.2447598-1-liu.yun@linux.dev (mailing list archive)
State Superseded
Headers show
Series ARM: s3c: irq-s3c24xx: Fix return value check for s3c24xx_init_intc() | expand

Commit Message

Jackie Liu Aug. 31, 2021, 9:57 a.m. UTC
From: Jackie Liu <liuyun01@kylinos.cn>

The s3c24xx_init_intc() returns an error pointer upon failure, not NULL.
let's add an error pointer check in s3c24xx_handle_irq.

Fixes: 1f629b7a3ced ("ARM: S3C24XX: transform irq handling into a declarative form")
Signed-off-by: Jackie Liu <liuyun01@kylinos.cn>
---
 arch/arm/mach-s3c/irq-s3c24xx.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Krzysztof Kozlowski Sept. 1, 2021, 12:09 p.m. UTC | #1
On 31/08/2021 11:57, Jackie Liu wrote:
> From: Jackie Liu <liuyun01@kylinos.cn>
> 
> The s3c24xx_init_intc() returns an error pointer upon failure, not NULL.
> let's add an error pointer check in s3c24xx_handle_irq.
> 
> Fixes: 1f629b7a3ced ("ARM: S3C24XX: transform irq handling into a declarative form")
> Signed-off-by: Jackie Liu <liuyun01@kylinos.cn>

Please use scripts/get_maintainers.pl to get list of mailing lists to
CC. You skipped two - arm and LKML.

> ---
>  arch/arm/mach-s3c/irq-s3c24xx.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm/mach-s3c/irq-s3c24xx.c b/arch/arm/mach-s3c/irq-s3c24xx.c
> index 0c631c14a817..d58bf0f9bf9a 100644
> --- a/arch/arm/mach-s3c/irq-s3c24xx.c
> +++ b/arch/arm/mach-s3c/irq-s3c24xx.c
> @@ -362,11 +362,11 @@ static inline int s3c24xx_handle_intc(struct s3c_irq_intc *intc,
>  static asmlinkage void __exception_irq_entry s3c24xx_handle_irq(struct pt_regs *regs)
>  {
>  	do {
> -		if (likely(s3c_intc[0]))
> +		if (likely(!IS_ERR_OR_NULL(s3c_intc[0])))
>  			if (s3c24xx_handle_intc(s3c_intc[0], regs, 0))

Thanks for the patch but it does not look entirely correct.

For platform based machines, neither ERR nor NULL can happen here.
The s3c24xx_handle_irq() will be set as IRQ handler iff this succeeds:
    s3c_intc[0] = s3c24xx_init_intc()

If this fails, the next calls to s3c24xx_init_intc() won't be executed.

For DT machine, s3c_init_intc_of() could set the IRQ handler without
setting s3c_intc[0] only if it was called with num_ctrl=0. There is no
such code path, so again the s3c_intc[0] will have a valid pointer if
set_handle_irq() is called.

Therefore in s3c24xx_handle_irq(), the s3c_intc[0] is always something.

The code can be simplified by removing if(), if we really wanted and
were sure about it.


>  				continue;
>  
> -		if (s3c_intc[2])
> +		if (!IS_ERR_OR_NULL(s3c_intc[2]))

For the non-DT case, this seems ugly but proper solution. The
s3c_intc[2] could be NULL (not set at all) or set as ERR (if
s3c24xx_init_intc() fails).

>  			if (s3c24xx_handle_intc(s3c_intc[2], regs, 64))
>  				continue;
>  
> 


Best regards,
Krzysztof
Jackie Liu Sept. 1, 2021, 12:28 p.m. UTC | #2
Hi Krzysztof, Thanks for you message.

在 2021/9/1 下午8:09, Krzysztof Kozlowski 写道:
> On 31/08/2021 11:57, Jackie Liu wrote:
>> From: Jackie Liu <liuyun01@kylinos.cn>
>>
>> The s3c24xx_init_intc() returns an error pointer upon failure, not NULL.
>> let's add an error pointer check in s3c24xx_handle_irq.
>>
>> Fixes: 1f629b7a3ced ("ARM: S3C24XX: transform irq handling into a declarative form")
>> Signed-off-by: Jackie Liu <liuyun01@kylinos.cn>
> 
> Please use scripts/get_maintainers.pl to get list of mailing lists to
> CC. You skipped two - arm and LKML.
> 
>> ---
>>   arch/arm/mach-s3c/irq-s3c24xx.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/arm/mach-s3c/irq-s3c24xx.c b/arch/arm/mach-s3c/irq-s3c24xx.c
>> index 0c631c14a817..d58bf0f9bf9a 100644
>> --- a/arch/arm/mach-s3c/irq-s3c24xx.c
>> +++ b/arch/arm/mach-s3c/irq-s3c24xx.c
>> @@ -362,11 +362,11 @@ static inline int s3c24xx_handle_intc(struct s3c_irq_intc *intc,
>>   static asmlinkage void __exception_irq_entry s3c24xx_handle_irq(struct pt_regs *regs)
>>   {
>>   	do {
>> -		if (likely(s3c_intc[0]))
>> +		if (likely(!IS_ERR_OR_NULL(s3c_intc[0])))
>>   			if (s3c24xx_handle_intc(s3c_intc[0], regs, 0))
> 
> Thanks for the patch but it does not look entirely correct.
> 
> For platform based machines, neither ERR nor NULL can happen here.
> The s3c24xx_handle_irq() will be set as IRQ handler iff this succeeds:
>      s3c_intc[0] = s3c24xx_init_intc()
> 
> If this fails, the next calls to s3c24xx_init_intc() won't be executed.
> 
> For DT machine, s3c_init_intc_of() could set the IRQ handler without
> setting s3c_intc[0] only if it was called with num_ctrl=0. There is no
> such code path, so again the s3c_intc[0] will have a valid pointer if
> set_handle_irq() is called.
> 
> Therefore in s3c24xx_handle_irq(), the s3c_intc[0] is always something.
> 
> The code can be simplified by removing if(), if we really wanted and
> were sure about it.

In fact, I didn't study his underlying logic in depth, but found that
this place was not particularly perfect based on the return value of the
function, because I happened to encounter a similar problem elsewhere.

> 
> 
>>   				continue;
>>   
>> -		if (s3c_intc[2])
>> +		if (!IS_ERR_OR_NULL(s3c_intc[2]))
> 
> For the non-DT case, this seems ugly but proper solution. The
> s3c_intc[2] could be NULL (not set at all) or set as ERR (if
> s3c24xx_init_intc() fails).
> 
>>   			if (s3c24xx_handle_intc(s3c_intc[2], regs, 64))
>>   				continue;
>>   
>>
> 
> 
> Best regards,
> Krzysztof
> 

Would you mind review v2?

--------------------------------------------------------------

diff --git a/arch/arm/mach-s3c/irq-s3c24xx.c 
b/arch/arm/mach-s3c/irq-s3c24xx.c
index 0c631c14a817..df471d322493 100644
--- a/arch/arm/mach-s3c/irq-s3c24xx.c
+++ b/arch/arm/mach-s3c/irq-s3c24xx.c
@@ -362,11 +362,24 @@ static inline int s3c24xx_handle_intc(struct 
s3c_irq_intc *intc,
  static asmlinkage void __exception_irq_entry s3c24xx_handle_irq(struct 
pt_regs *regs)
  {
         do {
-               if (likely(s3c_intc[0]))
-                       if (s3c24xx_handle_intc(s3c_intc[0], regs, 0))
-                               continue;
+               /* For platform based machines, neither ERR nor NULL can 
happen here.
+                * The s3c24xx_handle_irq() will be set as IRQ handler 
iff this succeeds:
+                *
+                *    s3c_intc[0] = s3c24xx_init_intc()
+                *
+                * If this fails, the next calls to s3c24xx_init_intc() 
won't be executed.
+                *
+                * For DT machine, s3c_init_intc_of() could set the IRQ 
handler without
+                * setting s3c_intc[0] only if it was called with 
num_ctrl=0. There is no
+                * such code path, so again the s3c_intc[0] will have a 
valid pointer if
+                * set_handle_irq() is called.
+                *
+                * Therefore in s3c24xx_handle_irq(), the s3c_intc[0] is 
always something.
+                */
+               if (s3c24xx_handle_intc(s3c_intc[0], regs, 0))
+                       continue;

-               if (s3c_intc[2])
+               if (!IS_ERR_OR_NULL(s3c_intc[2]))
                         if (s3c24xx_handle_intc(s3c_intc[2], regs, 64))
                                 continue;


---
Thanks, Jackie
Krzysztof Kozlowski Sept. 1, 2021, 12:31 p.m. UTC | #3
On 01/09/2021 14:28, Jackie Liu wrote:
> 
> Hi Krzysztof, Thanks for you message.
> 
> 在 2021/9/1 下午8:09, Krzysztof Kozlowski 写道:
>> On 31/08/2021 11:57, Jackie Liu wrote:
>>> From: Jackie Liu <liuyun01@kylinos.cn>
>>>
>>> The s3c24xx_init_intc() returns an error pointer upon failure, not NULL.
>>> let's add an error pointer check in s3c24xx_handle_irq.
>>>
>>> Fixes: 1f629b7a3ced ("ARM: S3C24XX: transform irq handling into a declarative form")
>>> Signed-off-by: Jackie Liu <liuyun01@kylinos.cn>
>>
>> Please use scripts/get_maintainers.pl to get list of mailing lists to
>> CC. You skipped two - arm and LKML.
>>
>>> ---
>>>   arch/arm/mach-s3c/irq-s3c24xx.c | 4 ++--
>>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/arch/arm/mach-s3c/irq-s3c24xx.c b/arch/arm/mach-s3c/irq-s3c24xx.c
>>> index 0c631c14a817..d58bf0f9bf9a 100644
>>> --- a/arch/arm/mach-s3c/irq-s3c24xx.c
>>> +++ b/arch/arm/mach-s3c/irq-s3c24xx.c
>>> @@ -362,11 +362,11 @@ static inline int s3c24xx_handle_intc(struct s3c_irq_intc *intc,
>>>   static asmlinkage void __exception_irq_entry s3c24xx_handle_irq(struct pt_regs *regs)
>>>   {
>>>   	do {
>>> -		if (likely(s3c_intc[0]))
>>> +		if (likely(!IS_ERR_OR_NULL(s3c_intc[0])))
>>>   			if (s3c24xx_handle_intc(s3c_intc[0], regs, 0))
>>
>> Thanks for the patch but it does not look entirely correct.
>>
>> For platform based machines, neither ERR nor NULL can happen here.
>> The s3c24xx_handle_irq() will be set as IRQ handler iff this succeeds:
>>      s3c_intc[0] = s3c24xx_init_intc()
>>
>> If this fails, the next calls to s3c24xx_init_intc() won't be executed.
>>
>> For DT machine, s3c_init_intc_of() could set the IRQ handler without
>> setting s3c_intc[0] only if it was called with num_ctrl=0. There is no
>> such code path, so again the s3c_intc[0] will have a valid pointer if
>> set_handle_irq() is called.
>>
>> Therefore in s3c24xx_handle_irq(), the s3c_intc[0] is always something.
>>
>> The code can be simplified by removing if(), if we really wanted and
>> were sure about it.
> 
> In fact, I didn't study his underlying logic in depth, but found that
> this place was not particularly perfect based on the return value of the
> function, because I happened to encounter a similar problem elsewhere.
> 
>>
>>
>>>   				continue;
>>>   
>>> -		if (s3c_intc[2])
>>> +		if (!IS_ERR_OR_NULL(s3c_intc[2]))
>>
>> For the non-DT case, this seems ugly but proper solution. The
>> s3c_intc[2] could be NULL (not set at all) or set as ERR (if
>> s3c24xx_init_intc() fails).
>>
>>>   			if (s3c24xx_handle_intc(s3c_intc[2], regs, 64))
>>>   				continue;
>>>   
>>>
>>
>>
>> Best regards,
>> Krzysztof
>>
> 
> Would you mind review v2?

Sure, please send it.


Best regards,
Krzysztof
diff mbox series

Patch

diff --git a/arch/arm/mach-s3c/irq-s3c24xx.c b/arch/arm/mach-s3c/irq-s3c24xx.c
index 0c631c14a817..d58bf0f9bf9a 100644
--- a/arch/arm/mach-s3c/irq-s3c24xx.c
+++ b/arch/arm/mach-s3c/irq-s3c24xx.c
@@ -362,11 +362,11 @@  static inline int s3c24xx_handle_intc(struct s3c_irq_intc *intc,
 static asmlinkage void __exception_irq_entry s3c24xx_handle_irq(struct pt_regs *regs)
 {
 	do {
-		if (likely(s3c_intc[0]))
+		if (likely(!IS_ERR_OR_NULL(s3c_intc[0])))
 			if (s3c24xx_handle_intc(s3c_intc[0], regs, 0))
 				continue;
 
-		if (s3c_intc[2])
+		if (!IS_ERR_OR_NULL(s3c_intc[2]))
 			if (s3c24xx_handle_intc(s3c_intc[2], regs, 64))
 				continue;