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As reported by Laurent, when a DVB frontend need to register two drivers (e. g. a tuner and a demod), if the second driver fails to register (for example because it was not compiled), the error handling logic frees the frontend by calling dvb_frontend_detach(). That used to work fine, but changeset1f862a68df("[media] dvb_frontend: move kref to struct dvb_frontend") added a kref at struct dvb_frontend. So, now, instead of just freeing the data, the error handling do a kref_put(). That works fine only after dvb_register_frontend() succeeds. While it would be possible to add a helper function that would be initializing earlier the kref, that would require changing every single DVB frontend on non-trivial ways, and would make frontends different than other drivers. So, instead of doing that, let's focus on the real issue: only call kref_put() after kref_init(). That's easy to check, as, when the dvb frontend is successfuly registered, it will allocate its own private struct. So, if such struct is allocated, it means that it is safe to use kref_put(). If not, then nobody is using yet the frontend, and it is safe to just deallocate it. Fixes:1f862a68df("[media] dvb_frontend: move kref to struct dvb_frontend") Reported-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.