[PATCH] Modify the return value ret to EOPNOTSUPP when initialized to reduce repeated assignment of errno

[PATCH] Modify the return value ret to EOPNOTSUPP when initialized to reduce repeated assignment of errno

[Zhang chunchao]

Remove unnecessary initialization assignments.

Signed-off-by: Zhang chunchao <chunchao@nfschina.com>
---
 io_uring/io_uring.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index b54218da075c..8c267af06401 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -3859,14 +3859,13 @@ SYSCALL_DEFINE4(io_uring_register, unsigned int, fd, unsigned int, opcode,
 		void __user *, arg, unsigned int, nr_args)
 {
 	struct io_ring_ctx *ctx;
-	long ret = -EBADF;
+	long ret = -EOPNOTSUPP;
 	struct fd f;
 
 	f = fdget(fd);
 	if (!f.file)
 		return -EBADF;
 
-	ret = -EOPNOTSUPP;
 	if (!io_is_uring_fops(f.file))
 		goto out_fput;
 
-- 
2.18.2

Re: [PATCH] Modify the return value ret to EOPNOTSUPP when initialized to reduce repeated assignment of errno

[Stefano Garzarella]

On Thu, Aug 11, 2022 at 03:56:38PM +0800, Zhang chunchao wrote:
>Remove unnecessary initialization assignments.
>
>Signed-off-by: Zhang chunchao <chunchao@nfschina.com>
>---
> io_uring/io_uring.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
>diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
>index b54218da075c..8c267af06401 100644
>--- a/io_uring/io_uring.c
>+++ b/io_uring/io_uring.c
>@@ -3859,14 +3859,13 @@ SYSCALL_DEFINE4(io_uring_register, unsigned int, fd, unsigned int, opcode,
> 		void __user *, arg, unsigned int, nr_args)
> {
> 	struct io_ring_ctx *ctx;
>-	long ret = -EBADF;
>+	long ret = -EOPNOTSUPP;
> 	struct fd f;
>
> 	f = fdget(fd);
> 	if (!f.file)
> 		return -EBADF;
>
>-	ret = -EOPNOTSUPP;
> 	if (!io_is_uring_fops(f.file))
> 		goto out_fput;
>

What about remove the initialization and assign it in the if branch?
I find it a bit easier to read.

I mean something like this:

--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -3859,16 +3859,17 @@ SYSCALL_DEFINE4(io_uring_register, unsigned int, fd, unsigned int, opcode,
                 void __user *, arg, unsigned int, nr_args)
  {
         struct io_ring_ctx *ctx;
-       long ret = -EBADF;
+       long ret;
         struct fd f;

         f = fdget(fd);
         if (!f.file)
                 return -EBADF;

-       ret = -EOPNOTSUPP;
-       if (!io_is_uring_fops(f.file))
+       if (!io_is_uring_fops(f.file)) {
+               ret = -EOPNOTSUPP;
                 goto out_fput;
+       }

         ctx = f.file->private_data;


Otherwise remove the initialization, but leave the assignment as it is 
now.

Thanks,
Stefano

Re: [PATCH] Modify the return value ret to EOPNOTSUPP when initialized to reduce repeated assignment of errno

[Jens Axboe]

On 8/11/22 9:02 AM, Stefano Garzarella wrote:
> On Thu, Aug 11, 2022 at 03:56:38PM +0800, Zhang chunchao wrote:
>> Remove unnecessary initialization assignments.
>>
>> Signed-off-by: Zhang chunchao <chunchao@nfschina.com>
>> ---
>> io_uring/io_uring.c | 3 +--
>> 1 file changed, 1 insertion(+), 2 deletions(-)
>>
>> diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
>> index b54218da075c..8c267af06401 100644
>> --- a/io_uring/io_uring.c
>> +++ b/io_uring/io_uring.c
>> @@ -3859,14 +3859,13 @@ SYSCALL_DEFINE4(io_uring_register, unsigned int, fd, unsigned int, opcode,
>>         void __user *, arg, unsigned int, nr_args)
>> {
>>     struct io_ring_ctx *ctx;
>> -    long ret = -EBADF;
>> +    long ret = -EOPNOTSUPP;
>>     struct fd f;
>>
>>     f = fdget(fd);
>>     if (!f.file)
>>         return -EBADF;
>>
>> -    ret = -EOPNOTSUPP;
>>     if (!io_is_uring_fops(f.file))
>>         goto out_fput;
>>
> 
> What about remove the initialization and assign it in the if branch?
> I find it a bit easier to read.
> 
> I mean something like this:
> 
> --- a/io_uring/io_uring.c
> +++ b/io_uring/io_uring.c
> @@ -3859,16 +3859,17 @@ SYSCALL_DEFINE4(io_uring_register, unsigned int, fd, unsigned int, opcode,
>                 void __user *, arg, unsigned int, nr_args)
>  {
>         struct io_ring_ctx *ctx;
> -       long ret = -EBADF;
> +       long ret;
>         struct fd f;
> 
>         f = fdget(fd);
>         if (!f.file)
>                 return -EBADF;
> 
> -       ret = -EOPNOTSUPP;
> -       if (!io_is_uring_fops(f.file))
> +       if (!io_is_uring_fops(f.file)) {
> +               ret = -EOPNOTSUPP;
>                 goto out_fput;
> +       }
> 
>         ctx = f.file->private_data;
> 
> 
> Otherwise remove the initialization, but leave the assignment as it is now.

Generally the kernel likes to do:

err = -EFOO;
if (something)
	goto err_out;

rather than put it inside the if clause. I guess the rationale is it
makes it harder to forget to init the error value. I don't feel too
strongly, I'm fine with your patch too. Can you send it as a real patch?

-- 
Jens Axboe

Re: [PATCH] Modify the return value ret to EOPNOTSUPP when initialized to reduce repeated assignment of errno

[Stefano Garzarella]

On Thu, Aug 11, 2022 at 09:41:38AM -0600, Jens Axboe wrote:
>On 8/11/22 9:02 AM, Stefano Garzarella wrote:
>> On Thu, Aug 11, 2022 at 03:56:38PM +0800, Zhang chunchao wrote:
>>> Remove unnecessary initialization assignments.
>>>
>>> Signed-off-by: Zhang chunchao <chunchao@nfschina.com>
>>> ---
>>> io_uring/io_uring.c | 3 +--
>>> 1 file changed, 1 insertion(+), 2 deletions(-)
>>>
>>> diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
>>> index b54218da075c..8c267af06401 100644
>>> --- a/io_uring/io_uring.c
>>> +++ b/io_uring/io_uring.c
>>> @@ -3859,14 +3859,13 @@ SYSCALL_DEFINE4(io_uring_register, unsigned int, fd, unsigned int, opcode,
>>>         void __user *, arg, unsigned int, nr_args)
>>> {
>>>     struct io_ring_ctx *ctx;
>>> -    long ret = -EBADF;
>>> +    long ret = -EOPNOTSUPP;
>>>     struct fd f;
>>>
>>>     f = fdget(fd);
>>>     if (!f.file)
>>>         return -EBADF;
>>>
>>> -    ret = -EOPNOTSUPP;
>>>     if (!io_is_uring_fops(f.file))
>>>         goto out_fput;
>>>
>>
>> What about remove the initialization and assign it in the if branch?
>> I find it a bit easier to read.
>>
>> I mean something like this:
>>
>> --- a/io_uring/io_uring.c
>> +++ b/io_uring/io_uring.c
>> @@ -3859,16 +3859,17 @@ SYSCALL_DEFINE4(io_uring_register, unsigned int, fd, unsigned int, opcode,
>>                 void __user *, arg, unsigned int, nr_args)
>>  {
>>         struct io_ring_ctx *ctx;
>> -       long ret = -EBADF;
>> +       long ret;
>>         struct fd f;
>>
>>         f = fdget(fd);
>>         if (!f.file)
>>                 return -EBADF;
>>
>> -       ret = -EOPNOTSUPP;
>> -       if (!io_is_uring_fops(f.file))
>> +       if (!io_is_uring_fops(f.file)) {
>> +               ret = -EOPNOTSUPP;
>>                 goto out_fput;
>> +       }
>>
>>         ctx = f.file->private_data;
>>
>>
>> Otherwise remove the initialization, but leave the assignment as it is now.
>
>Generally the kernel likes to do:
>
>err = -EFOO;
>if (something)
>	goto err_out;
>
>rather than put it inside the if clause. I guess the rationale is it
>makes it harder to forget to init the error value. I don't feel too

ah, thanks for pointing this out! Make sense to me, but I hope recent 
compilers can spot that kind of issue :-)

>strongly, I'm fine with your patch too. Can you send it as a real patch?

@Zhang: if you want, feel free to change your patch following the 
suggestions and send a new version, otherwise I can send mine of course.

Thanks,
Stefano