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1dfffa0051
The locks (active.lock and rq->lock) need to be taken with disabled interrupts. This is done in i915_request_retire() by disabling the interrupts independently of the locks itself. While local_irq_disable()+spin_lock() equals spin_lock_irq() on vanilla it does not on PREEMPT_RT. Chris Wilson confirmed that local_irq_disable() was just introduced as an optimisation to avoid enabling/disabling interrupts during lock/unlock combo. Enable/disable interrupts as part of the locking instruction. Cc: Chris Wilson <chris@chris-wilson.co.uk> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Link: https://patchwork.freedesktop.org/patch/msgid/20191017161352.e5z3ugse7gxl5ari@linutronix.de
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.