Re: [PATCH v3] kdb: remove unnecessary null check of dbg_io_ops

Sumit Garg
2020-06-30T11:36:47Z

On Tue, 30 Jun 2020 at 14:00, 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 | 14 +++++++-------
> 1 file changed, 7 insertions(+), 7 deletions(-)
>

Reviewed-by: Sumit Garg <sumit.garg@linaro.org>

> diff --git a/kernel/debug/kdb/kdb_io.c b/kernel/debug/kdb/kdb_io.c
> index 683a799618ad..81783ecaec58 100644
> --- a/kernel/debug/kdb/kdb_io.c
> +++ b/kernel/debug/kdb/kdb_io.c
> @@ -545,18 +545,18 @@ static int kdb_search_string(char *searched, char *searchfor)
> static void kdb_msg_write(const char *msg, int msg_len)
> {
> struct console *c;
> + const char *cp;
> + int len;
>
> if (msg_len == 0)
> return;
>
> - if (dbg_io_ops) {
> - const char *cp = msg;
> - int len = msg_len;
> + cp = msg;
> + len = msg_len;
>
> - while (len--) {
> - dbg_io_ops->write_char(*cp);
> - cp++;
> - }
> + while (len--) {
> + dbg_io_ops->write_char(*cp);
> + cp++;
> }
>
> for_each_console(c) {
> --
> 2.27.0
>