Re: kern/59081: Add close_range() system call

[Ricardo Branco <rbranco%suse.de@localhost>]

On 3/27/25 10:25 PM, Christos Zoulas via gnats wrote:
> The following reply was made to PR kern/59081; it has been noted by GNATS.
>
> From: Christos Zoulas <christos%zoulas.com@localhost>
> To: gnats-bugs%netbsd.org@localhost
> Cc: kern-bug-people%netbsd.org@localhost,
>   gnats-admin%netbsd.org@localhost,
>   netbsd-bugs%netbsd.org@localhost,
>   rbranco%suse.de@localhost
> Subject: Re: kern/59081: Add close_range() system call
> Date: Thu, 27 Mar 2025 17:20:09 -0400
>
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>   
>   Here is a complete patch: https://www.netbsd.org/~christos/close_range.diff
>   
>   christos
The whole approach with CLOSE_RANGE_UNSHARE is broken, meaning that
the current behaviour with the Linux emulation is broken.

It doesn't respect the fd range and unshares the whole filedesc structure:

https://github.com/NetBSD/src/blob/trunk/sys/compat/linux/common/linux_misc.c#L2090

The diff in https://www.netbsd.org/~christos/close_range.diff is doing 
the same.

Linux limits CLOSE_RANGE_UNSHARE to the specified range:

https://github.com/torvalds/linux/blob/master/fs/file.c#L788

So either we consider my patch in its original form or drop this attempt to
extend CLOSE_RANGE_UNSHARE to NetBSD.

Either way, the current Linux code needs fixing, which my patch does.

Best,
Ricardo.