CVS commit: src/sys/kern

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

Module Name:    src
Committed By:   riastradh
Date:           Sun Mar 20 13:17:32 UTC 2022

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

Log Message:
entropy(9): Lock the per-CPU state in entropy_account_cpu.

This was previously called with the per-CPU state locked, which
worked fine as long as the global entropy lock was a spin lock so
acquiring it would never sleep.  Now it's an adaptive lock, so it's
not safe to take with the per-CPU state lock -- but we still need to
prevent reentrant access to the per-CPU entropy pool by interrupt
handlers while we're extracting from it.  So now the logic for
entering a sample is:

- lock per-CPU state
- entpool_enter
- unlock per-CPU state
- if anything pending on this CPU and it's time to consolidate:
  - lock global entropy state
  - lock per-CPU state
  - transfer
  - unlock per-CPU state
  - unlock global entropy state


To generate a diff of this commit:
cvs rdiff -u -r1.43 -r1.44 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.