22fe5b0439
There is no point to update the TSS bitmap for tasks which use I/O bitmaps on every context switch. It's enough to update it right before exiting to user space. That reduces the context switch bitmap handling to invalidating the io bitmap base offset in the TSS when the outgoing task has TIF_IO_BITMAP set. The invaldiation is done on purpose when a task with an IO bitmap switches out to prevent any possible leakage of an activated IO bitmap. It also removes the requirement to update the tasks bitmap atomically in ioperm(). Signed-off-by: Thomas Gleixner <tglx@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.