CVS commit: src/sys/kern

["Taylor R Campbell" <riastradh%netbsd.org@localhost>]

Module Name:    src
Committed By:   riastradh
Date:           Fri Mar 18 23:34:56 UTC 2022

Modified Files:
        src/sys/kern: kern_entropy.c

Log Message:
entropy(9): Use the early-entropy path only while cold.

This way, we never take the global entropy lock from interrupt
handlers (no interrupts while cold), so the global entropy lock need
not block interrupts.

There's an annoying ordering issue here: softint_establish doesn't
work until after CPUs have been detected, which happens inside
configure(), which is also what enables interrupts.  So we have no
opportunity to softint_establish the entropy softint _before_
interrupts are enabled.

To work around this, we have to put a conditional into the interrupt
path, and go out of our way to process any queued samples after
establishing the softint.  If we just made softint_establish work
early, like percpu_create does now, this problem would go away and we
could delete a bit of logic here.

Candidate fix for PR kern/56730.


To generate a diff of this commit:
cvs rdiff -u -r1.36 -r1.37 src/sys/kern/kern_entropy.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.