9148de3196
Currently, we reseed when random bytes are requested, if the current seed is too old. Since random bytes can be requested from all contexts, including hard IRQ, this means sometimes we wind up adding a bit of latency to hard IRQ. This was so much of a problem on s390x that now s390x just doesn't provide its architectural RNG from hard IRQ context, so we miss out in that case. Instead, let's just schedule a persistent delayed work, so that the reseeding and potentially expensive operations will always happen from process context, reducing unexpected latencies from hard IRQ. This also has the nice effect of accumulating a transcript of random inputs over time, since it means that we amass more input values. And it should make future vDSO integration a bit easier. Cc: Harald Freudenberger <freude@linux.ibm.com> Cc: Juergen Christ <jchrist@linux.ibm.com> Cc: Alexander Gordeev <agordeev@linux.ibm.com> Cc: Dominik Brodowski <linux@dominikbrodowski.net> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.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.