The proper use of EXPORT_SYMBOL_GPL()

The kernel, in theory, puts strict limits on which functions and data structures are available to loadable kernel modules; only those that have been explicitly exported with EXPORT_SYMBOL() or EXPORT_SYMBOL_GPL() are accessible. In the case of EXPORT_SYMBOL_GPL(), only modules that declare a GPL-compatible license will be able to see the symbol. There have been questions about when EXPORT_SYMBOL_GPL() should be used for almost as long as it has existed. The latest attempt to answer those questions was a session run by Greg Kroah-Hartman at the 2018 Kernel Maintainers Summit; that session offered little in the way of general guidance, but it did address one specific case.

Full Story (comments: 7)