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

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

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---

• References:
  • [PATCH -mm 1/9] unshare system call: system call handler function
    • From: JANAK DESAI <[email protected]>
  • Re: [PATCH -mm 1/9] unshare system call: system call handler function
    • From: [email protected] (Eric W. Biederman)
  • Re: [PATCH -mm 1/9] unshare system call: system call handler function
    • From: JANAK DESAI <[email protected]>
  • Re: [PATCH -mm 1/9] unshare system call: system call handler function
    • From: [email protected] (Eric W. Biederman)
  • Re: [PATCH -mm 1/9] unshare system call: system call handler function
    • From: Jamie Lokier <[email protected]>

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