Re: + unshare-use-swap-to-make-code-cleaner.patch added to -mm tree

[ebiederm@xmission.com (Eric W. Biederman)]

akpm@linux-foundation.org writes:

> The patch titled
>      Subject: kernel/fork.c: unshare(): use swap() to make code cleaner
> has been added to the -mm tree.  Its filename is
>      unshare-use-swap-to-make-code-cleaner.patch
>
> This patch should soon appear at
>     https://ozlabs.org/~akpm/mmots/broken-out/unshare-use-swap-to-make-code-cleaner.patch
> and later at
>     https://ozlabs.org/~akpm/mmotm/broken-out/unshare-use-swap-to-make-code-cleaner.patch
>
> Before you just go and hit "reply", please:
>    a) Consider who else should be cc'ed
>    b) Prefer to cc a suitable mailing list as well
>    c) Ideally: find the original patch on the mailing list and do a
>       reply-to-all to that, adding suitable additional cc's
>
> *** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
>
> The -mm tree is included into linux-next and is updated
> there every 3-4 working days

Why is the swap macro spelled in lower case?

Given that there is no way to write swap as a function I would think we
would want to write SWAP instead of swap to make it clear swap is a
macro.

Eric


> ------------------------------------------------------
> From: Ran Xiaokai <ran.xiaokai@zte.com.cn>
> Subject: kernel/fork.c: unshare(): use swap() to make code cleaner
>
> Use swap() instead of reimplementing it.
>
> Link: https://lkml.kernel.org/r/20210909022046.8151-1-ran.xiaokai@zte.com.cn
> Signed-off-by: Ran Xiaokai <ran.xiaokai@zte.com.cn>
> Cc: Gabriel Krisman Bertazi <krisman@collabora.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Eric W. Biederman <ebiederm@xmission.com>
> Cc: Jens Axboe <axboe@kernel.dk>
> Cc: Alexey Gladkov <legion@kernel.org>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> ---
>
>  kernel/fork.c |    9 +++------
>  1 file changed, 3 insertions(+), 6 deletions(-)
>
> --- a/kernel/fork.c~unshare-use-swap-to-make-code-cleaner
> +++ a/kernel/fork.c
> @@ -3078,7 +3078,7 @@ int unshare_fd(unsigned long unshare_fla
>  int ksys_unshare(unsigned long unshare_flags)
>  {
>  	struct fs_struct *fs, *new_fs = NULL;
> -	struct files_struct *fd, *new_fd = NULL;
> +	struct files_struct *new_fd = NULL;
>  	struct cred *new_cred = NULL;
>  	struct nsproxy *new_nsproxy = NULL;
>  	int do_sysvsem = 0;
> @@ -3165,11 +3165,8 @@ int ksys_unshare(unsigned long unshare_f
>  			spin_unlock(&fs->lock);
>  		}
>  
> -		if (new_fd) {
> -			fd = current->files;
> -			current->files = new_fd;
> -			new_fd = fd;
> -		}
> +		if (new_fd)
> +			swap(current->files, new_fd);
>  
>  		task_unlock(current);
>  
> _
>
> Patches currently in -mm which might be from ran.xiaokai@zte.com.cn are
>
> unshare-use-swap-to-make-code-cleaner.patch