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The fpu_recursion_depth counter is used to ensure that dc_fpu_begin() can be invoked multiple times while the FPU-disable function itself is only invoked once. Also the counter part (dc_fpu_end()) is ballanced properly. Instead of using the get_cpu_ptr() dance around the inc it is simpler to increment the per-CPU variable directly. Also the per-CPU variable has to be incremented and decremented on the same CPU. This is ensured by the inner-part which disables preemption. This is kind of not obvious, works and the preempt-counter is touched a few times for no reason. Disable preemption before incrementing fpu_recursion_depth for the first time. Keep preemption disabled until dc_fpu_end() where the counter is decremented making it obvious that the preemption has to stay disabled while the counter is non-zero. Use simple inc/dec functions. Remove the nested preempt_disable/enable functions which are now not needed. Acked-by: Harry Wentland <harry.wentland@amd.com> Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
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.