linux-kernel - Re: [PATCH] gpiolib: demote the hogging log messages to debug

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAL_JsqKDQy+tq7uDJ9impTr+uetkb7vz-K4BYX8bZBkpvZ=8uQ@mail.gmail.com>
Date:   Mon, 12 Jun 2023 09:42:43 -0600
From:   Rob Herring <robh+dt@...nel.org>
To:     Frank Rowand <frowand.list@...il.com>
Cc:     Bartosz Golaszewski <brgl@...ev.pl>,
        Linus Walleij <linus.walleij@...aro.org>,
        Kent Gibson <warthog618@...il.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org,
        Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH] gpiolib: demote the hogging log messages to debug

On Sun, Jun 11, 2023 at 6:48 AM Frank Rowand <frowand.list@...il.com> wrote:
>
> On 6/11/23 07:39, Frank Rowand wrote:
> > On 6/9/23 08:47, Rob Herring wrote:
> >> On Mon, Jun 5, 2023 at 6:53 AM Bartosz Golaszewski <brgl@...ev.pl> wrote:
> >>>
> >>> From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> >>>
> >>> Drivers should be silent when they work correctly. There's no reason to
> >>> emit info messages when GPIO lines are hogged. Demote the message to
> >>> debug.
> >>>
> >>> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> >>> Suggested-by: Kent Gibson <warthog618@...il.com>
> >>> ---
> >>>  drivers/gpio/gpiolib.c |  2 +-
> >>>  drivers/of/unittest.c  | 16 ++++++++--------
> >>>  2 files changed, 9 insertions(+), 9 deletions(-)
> >>>
> >>> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> >>> index a7220e04a93e..e4515bda8915 100644
> >>> --- a/drivers/gpio/gpiolib.c
> >>> +++ b/drivers/gpio/gpiolib.c
> >>> @@ -4243,7 +4243,7 @@ int gpiod_hog(struct gpio_desc *desc, const char *name,
> >>>         /* Mark GPIO as hogged so it can be identified and removed later */
> >>>         set_bit(FLAG_IS_HOGGED, &desc->flags);
> >>>
> >>> -       gpiod_info(desc, "hogged as %s%s\n",
> >>> +       gpiod_dbg(desc, "hogged as %s%s\n",
> >>>                 (dflags & GPIOD_FLAGS_BIT_DIR_OUT) ? "output" : "input",
> >>>                 (dflags & GPIOD_FLAGS_BIT_DIR_OUT) ?
> >>>                   (dflags & GPIOD_FLAGS_BIT_DIR_VAL) ? "/high" : "/low" : "");
> >>> diff --git a/drivers/of/unittest.c b/drivers/of/unittest.c
> >>> index 2191c0136531..0060334a98a7 100644
> >>> --- a/drivers/of/unittest.c
> >>> +++ b/drivers/of/unittest.c
> >>> @@ -1849,19 +1849,19 @@ static void __init of_unittest_overlay_gpio(void)
> >>>          * driver is registered
> >>>          */
> >>>
> >>> -       EXPECT_BEGIN(KERN_INFO,
> >>> +       EXPECT_BEGIN(KERN_DEBUG,
> >>>                      "gpio-<<int>> (line-B-input): hogged as input\n");
> >>
> >> As debug messages are normally off, I think you can just remove these.
> >
> > This patch is an example of exactly why the message level is the first parameter
> > passed to EXPECT_*().  The test results are then _always_ valid, not just
> > _normally_.
>
> One should never say never.  One should never say always. :-)
>
> Yes, there is still the exception where debug can be enabled independently
> for drivers/gpio/gpiolib.c  vs for drivers/of/unittest.c.  And dynamic
> debug can make things even more wonky.

If we turned on debug messages for drivers/of/, the unittest would be
hopelessly broken.

Debug messages are special compared to all the other levels as they
are normally off whereas the rest are always on. For the unittest we
should assume they are off.

Rob