Re: [PATCH] fsi: fix bogos error returns from cfam_read and cfam_write

[Joel Stanley]

Hi Colin,

On Fri, 22 Nov 2019 at 23:31, Colin King <colin.king@xxxxxxxxxxxxx> wrote:
>
> From: Colin Ian King <colin.king@xxxxxxxxxxxxx>
>
> In the case where errors occur in functions cfam_read and cfam_write
> the error return code in rc is not returned and a bogus non-error
> count size is returned instead. Fix this by returning the correct
> error code when an error occurs or the count size if the functions
> worked correctly.

 You're correct that if there's an error we need to return an error.

However the other case is when there's a partial read that completed.
We already advance the file offset, but I think we should also return
the number of bytes successfully read.

Cheers,

Joel

>
> Addresses-Coverity: ("Unused value")
> Fixes: d1dcd6782576 ("fsi: Add cfam char devices")
> Signed-off-by: Colin Ian King <colin.king@xxxxxxxxxxxxx>
> ---
>  drivers/fsi/fsi-core.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/fsi/fsi-core.c b/drivers/fsi/fsi-core.c
> index 8244da8a7241..c3885b138ead 100644
> --- a/drivers/fsi/fsi-core.c
> +++ b/drivers/fsi/fsi-core.c
> @@ -718,7 +718,7 @@ static ssize_t cfam_read(struct file *filep, char __user *buf, size_t count,
>         rc = count;
>   fail:
>         *offset = off;
> -       return count;
> +       return rc;
>  }
>
>  static ssize_t cfam_write(struct file *filep, const char __user *buf,
> @@ -755,7 +755,7 @@ static ssize_t cfam_write(struct file *filep, const char __user *buf,
>         rc = count;
>   fail:
>         *offset = off;
> -       return count;
> +       return rc;
>  }
>
>  static loff_t cfam_llseek(struct file *file, loff_t offset, int whence)
> --
> 2.24.0
>