gcc warns about an out-of-bounds access when the using nonzero values for 'plane_id' on kmb->plane_status: drivers/gpu/drm/kmb/kmb_plane.c: In function 'kmb_plane_atomic_disable': drivers/gpu/drm/kmb/kmb_plane.c:128:20: warning: array subscript 3 is above array bounds of 'struct layer_status[1]' [-Warray-bounds] 128 | kmb->plane_status[plane_id].ctrl = LCD_CTRL_GL2_ENABLE; | ~~~~~~~~~~~~~~~~~^~~~~~~~~~ drivers/gpu/drm/kmb/kmb_plane.c:125:20: warning: array subscript 2 is above array bounds of 'struct layer_status[1]' [-Warray-bounds] 125 | kmb->plane_status[plane_id].ctrl = LCD_CTRL_GL1_ENABLE; | ~~~~~~~~~~~~~~~~~^~~~~~~~~~ drivers/gpu/drm/kmb/kmb_plane.c:122:20: warning: array subscript 1 is above array bounds of 'struct layer_status[1]' [-Warray-bounds] 122 | kmb->plane_status[plane_id].ctrl = LCD_CTRL_VL2_ENABLE; Having the array truncated to one entry seems intentional, so add a range check before indexing it to make it clearer what is going on and shut up the warning. I received the warning from the kernel test robot after a private patch that turns on Warray-bounds unconditionally. Fixes: 7f7b96a8a0a1 ("drm/kmb: Add support for KeemBay Display") Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Anitha Chrisanthus <anitha.chrisanthus@intel.com> Signed-off-by: Sam Ravnborg <sam@ravnborg.org> Link: https://patchwork.freedesktop.org/patch/msgid/20201129200927.1854104-1-arnd@kernel.org
Linux kernel ============ There are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. Please read Documentation/admin-guide/README.rst first. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. The formatted documentation can also be read online at: https://www.kernel.org/doc/html/latest/ There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.
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