Re: [PATCH -mm 1/9] unshare system call: system call handler function

[JANAK DESAI <janak@us.ibm.com>]

Jamie Lokier wrote:

>Eric W. Biederman wrote:
>  
>
>>I follow but I am very disturbed.
>>
>>You are leaving CLONE_NEWNS to mean you want a new namespace.
>>
>>For clone CLONE_FS unset means generate an unshared fs_struct
>>          CLONE_FS set   means share the fs_struct with the parent
>>
>>But for unshare CLONE_FS unset means share the fs_struct with others
>>            and CLONE_FS set   means generate an unshared fs_struct
>>
>>The meaning of CLONE_FS between the two calls in now flipped,
>>but CLONE_NEWNS is not.  Please let's not implement it this way.
>>    
>>
>
>I agree.
>
>  
>
>>Part of the problem is the double negative in the name, leading
>>me to suggest that sys_share might almost be a better name.
>>    
>>
>
>I agree with that suggestion, too.
>
>Alternatively, we could just add a flag to clone(): CLONE_SELF,
>meaning don't create a new task, just modify the properties of the
>current task.
>  
>
... and this won't cause confusion :-) ? Clone to me implies that a second
entity is being created.

>  
>
>>So please code don't invert the meaning of the bits.  This will
>>allow sharing of the sanity checks with clone.
>>In addition this leaves open the possibility that routines like
>>copy_fs properly refactored can be shared between clone and unshare.
>>    
>>
>
>And also make the API less confusing to document and use.
>
>-- Jamie
>
>  
>
I am all for less confusing API and saner semantics. I will take a look
at yours and Eric's suggestions to see what can be done.

Thanks.

-Janak