Re: [PATCH] kernfs: move return value check after kmalloc()

From: NeilBrown
Date: Thu May 20 2021 - 23:29:30 EST


On Fri, 21 May 2021, Austin Kim wrote:
> With 414985ae23c0 ("sysfs, kernfs: move file core code to fs/kernfs/file.c"),
> 'return -ENOMEM' is executed when kmalloc() returns NULL.
>
> Since 'commit 4ef67a8c95f3 ("sysfs/kernfs: make read requests on pre-alloc
> files use the buffer.")', 'return -ENOMEM' statement is not properly located.
>
> Fix it by moving 'return -ENOMEM' after return from kmalloc().

I don't think there is anything to "fix" here. The current code is
correct.
The difference between the current code and your new code is purely a
difference in style. I don't object to your change, but only if it is
presented as a style improvement. It is not a code fix.

NeilBrown


>
> Fixes: 4ef67a8c95f3 ("sysfs/kernfs: make read requests on pre-alloc files use the buffer.")
> Signed-off-by: Austin Kim <austindh.kim@xxxxxxxxx>
> ---
> fs/kernfs/file.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c
> index c75719312147..c5e2429af836 100644
> --- a/fs/kernfs/file.c
> +++ b/fs/kernfs/file.c
> @@ -191,10 +191,11 @@ static ssize_t kernfs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
> buf = of->prealloc_buf;
> if (buf)
> mutex_lock(&of->prealloc_mutex);
> - else
> + else {
> buf = kmalloc(len, GFP_KERNEL);
> - if (!buf)
> - return -ENOMEM;
> + if (!buf)
> + return -ENOMEM;
> + }
>
> /*
> * @of->mutex nests outside active ref and is used both to ensure that
> --
> 2.20.1
>
>