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Several drivers call subdev pad operations, passing structures that are not fully zeroed. While the drivers initialize the fields they care about explicitly, this results in reserved fields having uninitialized values. Future kernel API changes that make use of those fields thus risk breaking proper driver operation in ways that could be hard to detect. To avoid this, make the code more robust by zero-initializing all the structures passed to subdev pad operation. Maintain a consistent coding style by preferring designated initializers (which zero-initialize all the fields that are not specified) over memset() where possible, and make variable declarations local to inner scopes where applicable. One notable exception to this rule is in the ipu3 driver, where a memset() is needed as the structure is not a local variable but a function parameter provided by the caller. Not all fields of those structures can be initialized when declaring the variables, as the values for those fields are computed later in the code. Initialize the 'which' field in all cases, and other fields when the variable declaration is so close to the v4l2_subdev_call() call that it keeps all the context easily visible when reading the code, to avoid hindering readability. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Acked-by: Shuah Khan <skhan@linuxfoundation.org> # For vimc Reviewed-by: Lad Prabhakar <prabhakar.csengg@gmail.com> # For am437x Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com> Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com> Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com> Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de> # For drivers/staging/media/imx/ Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
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.