linux-kernel - Re: [PATCH v3] kdb: remove unnecessary null check of dbg_io

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Date:   Tue, 30 Jun 2020 14:48:53 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Sumit Garg <sumit.garg@...aro.org>
Cc:     Cengiz Can <cengiz@...nel.wtf>,
        Daniel Thompson <daniel.thompson@...aro.org>,
        Douglas Anderson <dianders@...omium.org>,
        Jason Wessel <jason.wessel@...driver.com>,
        kgdb-bugreport@...ts.sourceforge.net,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Petr Mladek <pmladek@...e.com>
Subject: Re: [PATCH v3] kdb: remove unnecessary null check of dbg_io_ops

On Tue, Jun 30, 2020 at 05:06:31PM +0530, Sumit Garg wrote:
> On Tue, 30 Jun 2020 at 14:00, Cengiz Can <cengiz@...nel.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.

> > -               while (len--) {
> > -                       dbg_io_ops->write_char(*cp);
> > -                       cp++;
> > -               }
> > +       while (len--) {
> > +               dbg_io_ops->write_char(*cp);
> > +               cp++;
> >         }

Despite being in the original code this can be simple done in two lines:

	while (len--)
		dbg_io_ops->write_char(*cp++);

-- 
With Best Regards,
Andy Shevchenko