CVS commit: [netbsd-9] src/sys/kern

["Martin Husemann" <martin%netbsd.org@localhost>]

Module Name:    src
Committed By:   martin
Date:           Wed Oct 18 15:07:06 UTC 2023

Modified Files:
        src/sys/kern [netbsd-9]: subr_thmap.c

Log Message:
Pull up following revision(s) (requested by riastradh in ticket #1755):

        sys/kern/subr_thmap.c: revision 1.14
        sys/kern/subr_thmap.c: revision 1.15

thmap(9): Test alloc failure, not THMAP_GETPTR failure.
THMAP_GETPTR may return nonnull even though alloc returned zero.

Note that this failure branch is not actually appropriate;
thmap_create should not fail.  We really need to pass KM_SLEEP
through in this call site even though there are other call sites for
which KM_NOSLEEP is appropriate.

Adapted from: https://github.com/rmind/thmap/pull/14
PR kern/57666
https://github.com/rmind/thmap/issues/13

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


To generate a diff of this commit:
cvs rdiff -u -r1.5.6.1 -r1.5.6.2 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.