From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Date: Tue, 22 May 2012 20:59:02 +0000 Subject: Re: [PATCH] backlight: initialize struct backlight_properties properly Message-Id: <20120522135902.90253d07.akpm@linux-foundation.org> List-Id: References: <1337585085-4891-1-git-send-email-corentin.chary@gmail.com> In-Reply-To: <1337585085-4891-1-git-send-email-corentin.chary@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Corentin Chary Cc: Arnd Bergmann , Mathieu Poirier , Tobias Schandinat , Mark Brown , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, platform-driver-x86@vger.kernel.org, patches@opensource.wolfsonmicro.com, Florian@freedesktop.org, Dave@freedesktop.org, Richard Purdie , linux-fbdev@vger.kernel.org, Lars-Peter@freedesktop.org, Airlie , Axel Lin , linux-omap@vger.kernel.org, Matthew Garrett On Mon, 21 May 2012 09:24:35 +0200 Corentin Chary wrote: > In all these files, the .power field was never correctly initialized. > > ... > > --- a/drivers/gpu/drm/i915/intel_panel.c > +++ b/drivers/gpu/drm/i915/intel_panel.c > @@ -342,6 +342,7 @@ int intel_panel_setup_backlight(struct drm_device *dev) > else > return -ENODEV; > > + memset(&props, 0, sizeof(props)); This code is all still quite fragile. What happens if we add a new field to backlight_properties? We need to go edit a zillion drivers? There are two ways of fixing this: a) write and use void backlight_properties_init(struct backlight_properties *props, int type, int max_brightness, etc); or b) edit all sites to do struct backlight_properties bl_props = { .type = BACKLIGHT_RAW, .max_brighness = intel_panel_get_max_backlight(dev), .power = FB_BLANK_UNBLANK, }; they're largely equivalent - the struct will be zeroed out and then certain fields will be initialised. a) is a bit better because some future field may not want the all-zeroes pattern (eg, a spinlock). But they're both better than what we have now!