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Aside of being conceptually wrong, there is also an actual (hard to trigger and mostly theoretical) problem. CPU0 CPU1 free_irq(X) interrupt X spin_lock(desc->lock) wake irq thread() spin_unlock(desc->lock) spin_lock(desc->lock) remove action() shutdown_irq() release_resources() thread_handler() spin_unlock(desc->lock) access released resources. synchronize_irq() Move the release resources invocation after synchronize_irq() so it's guaranteed that the threaded handler has finished. Move the resource request call out of the desc->lock held region as well, so the invocation context is the same for both request and release. This solves the problems with those functions on RT as well. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Marc Zyngier <marc.zyngier@arm.com> Cc: Heiko Stuebner <heiko@sntech.de> Cc: Julia Cartwright <julia@ni.com> Cc: Linus Walleij <linus.walleij@linaro.org> Cc: Brian Norris <briannorris@chromium.org> Cc: Doug Anderson <dianders@chromium.org> Cc: linux-rockchip@lists.infradead.org Cc: John Keeping <john@metanate.com> Cc: linux-gpio@vger.kernel.org Link: http://lkml.kernel.org/r/20170629214344.117028181@linutronix.de
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.