Re: [PATCH v2] kdb: remove unnecessary null check of dbg_io_ops

Doug Anderson
2020-06-29T21:16:58Z

Hi,

On Mon, Jun 29, 2020 at 1:50 PM Cengiz Can <cengiz@kernel.wtf> wrote:
>
> `kdb_msg_write` operates on a global `struct kgdb_io *` called
> `dbg_io_ops`.
>
> It's initialized in `debug_core.c` and checked throughout the debug
> flow.
>
> There's a null check in `kdb_msg_write` which triggers static analyzers
> and gives the (almost entirely wrong) impression that it can be null.
>
> Coverity scanner caught this as CID 1465042.
>
> I have removed the unnecessary null check and eliminated false-positive
> forward null dereference warning.
>
> Signed-off-by: Cengiz Can <cengiz@kernel.wtf>
> ---
> kernel/debug/kdb/kdb_io.c | 12 +++++-------
> 1 file changed, 5 insertions(+), 7 deletions(-)
>
> diff --git a/kernel/debug/kdb/kdb_io.c b/kernel/debug/kdb/kdb_io.c
> index 683a799618ad..4ac59a4fbeec 100644
> --- a/kernel/debug/kdb/kdb_io.c
> +++ b/kernel/debug/kdb/kdb_io.c
> @@ -549,14 +549,12 @@ static void kdb_msg_write(const char *msg, int msg_len)
> if (msg_len == 0)
> return;
>
> - if (dbg_io_ops) {
> - const char *cp = msg;
> - int len = msg_len;
> + const char *cp = msg;
> + int len = msg_len;

kernel/debug/kdb/kdb_io.c:552:14:
warning: ISO C90 forbids mixing declarations and code
[-Wdeclaration-after-statement]

-Doug