Re: [PATCH v2 11/13] drm/modes: parse_cmdline: Explicitly memset the passed in drm_cmdline_mode struct

From: Maxime Ripard <mripard@kernel.org>
To: Hans de Goede <hdegoede@redhat.com>
Cc: "David Airlie" <airlied@linux.ie>,
	"Derek Basehore" <dbasehore@chromium.org>,
	dri-devel@lists.freedesktop.org,
	"Sean Paul" <seanpaul@chromium.org>,
	"Daniel Vetter" <daniel.vetter@intel.com>,
	"Mathieu Alexandre-Tétreault" <alexandretm@amotus.ca>
Subject: Re: [PATCH v2 11/13] drm/modes: parse_cmdline: Explicitly memset the passed in drm_cmdline_mode struct
Date: Mon, 18 Nov 2019 13:28:16 +0100	[thread overview]
Message-ID: <20191118122816.GJ4345@gilmour.lan> (raw)
In-Reply-To: <20191113164434.254159-11-hdegoede@redhat.com>

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On Wed, Nov 13, 2019 at 05:44:32PM +0100, Hans de Goede wrote:
> Instead of only setting mode->specified on false on an early exit and
> leaving e.g. mode->bpp_specified and mode->refresh_specified as is,
> lets be consistent and just zero out the entire passed in struct at
> the top of drm_mode_parse_command_line_for_connector()
>
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> ---
>  drivers/gpu/drm/drm_modes.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c
> index beb764efe6b3..1fee4a71eff7 100644
> --- a/drivers/gpu/drm/drm_modes.c
> +++ b/drivers/gpu/drm/drm_modes.c
> @@ -1745,12 +1745,11 @@ bool drm_mode_parse_command_line_for_connector(const char *mode_option,
>  	char *bpp_end_ptr = NULL, *refresh_end_ptr = NULL;
>  	int i, len, ret;
>
> +	memset(mode, 0, sizeof(*mode));
>  	mode->panel_orientation = DRM_MODE_PANEL_ORIENTATION_UNKNOWN;

The reported error by kbuild rings a bell. I think I tried to do this,
saw that error, and then forgot about it.

Looking more at the code now, I don't see any in bochs that looks
really wrong. Either way, we should either fix bochs, or add a
unit-test to have a test for the bochs case so that we don't have that
issue sneaking around.

(btw, thanks for adding more tests, that's really appreciated)

Maxime

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