linux-kernel - Re: [PATCH] habanalabs: added return value check for hl_fw_dynamic_send_clear

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Message-ID: <CAFCwf1193-TiMdx3unuHC1H4zK+7qYg_4A5mtOB7VGmqZ6M6HQ@mail.gmail.com>
Date:   Thu, 17 Nov 2022 10:45:57 +0200
From:   Oded Gabbay <ogabbay@...nel.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Marco Pagani <marpagan@...hat.com>, Arnd Bergmann <arnd@...db.de>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Tom Rix <trix@...hat.com>, linux-kernel@...r.kernel.org,
        llvm@...ts.linux.dev
Subject: Re: [PATCH] habanalabs: added return value check for hl_fw_dynamic_send_clear_cmd()

On Wed, Nov 16, 2022 at 5:17 PM Greg Kroah-Hartman
<gregkh@...uxfoundation.org> wrote:
>
> On Wed, Nov 16, 2022 at 02:41:25PM +0100, Marco Pagani wrote:
> > The clang-analyzer reported a warning: "Value stored to 'rc' is never
> > read".
> >
> > The return value check for the first hl_fw_dynamic_send_clear_cmd() call
> > in hl_fw_dynamic_send_protocol_cmd() appears to be missing.
> >
> > Signed-off-by: Marco Pagani <marpagan@...hat.com>
> > ---
> >  drivers/misc/habanalabs/common/firmware_if.c | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/misc/habanalabs/common/firmware_if.c b/drivers/misc/habanalabs/common/firmware_if.c
> > index 2de6a9bd564d..311942108dbc 100644
> > --- a/drivers/misc/habanalabs/common/firmware_if.c
> > +++ b/drivers/misc/habanalabs/common/firmware_if.c
> > @@ -1782,6 +1782,8 @@ int hl_fw_dynamic_send_protocol_cmd(struct hl_device *hdev,
> >
> >       /* first send clear command to clean former commands */
> >       rc = hl_fw_dynamic_send_clear_cmd(hdev, fw_loader);
> > +     if (rc)
> > +             return rc;
> >
> >       /* send the actual command */
> >       hl_fw_dynamic_send_cmd(hdev, fw_loader, cmd, size);
>
> Are you sure this is ok?  If the first "clean the buffer" command fails,
> all should still be good as that wasn't the real command.
>
> But maybe the hardware will never fail this?
>
> thanks,
>
> greg k-h

Actually it's a real mistake, it was overlooked when the code was
written (although chances of failure in clear cmd are very small).
I'll apply it to my tree.
Reviewed-by: Oded Gabbay <ogabbay@...nel.org>
Thanks,
Oded