CVS commit: src/sys/kern

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

Module Name:    src
Committed By:   riastradh
Date:           Tue Oct 17 11:57:20 UTC 2023

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

Log Message:
thmap(9): Preallocate GC list storage for thmap_del.

thmap_del can't fail, and it is used in places in npf where sleeping
is forbidden, so it can't rely on allocating memory either.

Instead of having thmap_del allocate memory on the fly for each
object to defer freeing until thmap_gc, arrange to have thmap(9)
preallocate the same storage when allocating all the objects in the
first place, with a GC header.

This is suboptimal for memory usage, especially on insertion- and
lookup-heavy but deletion-light workloads, but it's not clear rmind's
alternative (https://github.com/rmind/thmap/tree/thmap_del_mem_fail)
is ready to use yet, so we'll go with this for correctness.

PR kern/57208
https://github.com/rmind/npf/issues/129

XXX pullup-10
XXX pullup-9


To generate a diff of this commit:
cvs rdiff -u -r1.14 -r1.15 src/sys/kern/subr_thmap.c

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