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| Current File : //sys/amd64/compile/hs32/modules/usr/src/sys/modules/ata/atapci/chipsets/atacyrix/@/geom/bde/g_bde_work.c |
/*-
* Copyright (c) 2002 Poul-Henning Kamp
* Copyright (c) 2002 Networks Associates Technology, Inc.
* All rights reserved.
*
* This software was developed for the FreeBSD Project by Poul-Henning Kamp
* and NAI Labs, the Security Research Division of Network Associates, Inc.
* under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
* DARPA CHATS research program.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $FreeBSD: release/9.1.0/sys/geom/bde/g_bde_work.c 172836 2007-10-20 23:23:23Z julian $
*/
/*
* This source file contains the state-engine which makes things happen in the
* right order.
*
* Outline:
* 1) g_bde_start1()
* Break the struct bio into multiple work packets one per zone.
* 2) g_bde_start2()
* Setup the necessary sector buffers and start those read operations
* which we can start at this time and put the item on the work-list.
* 3) g_bde_worker()
* Scan the work-list for items which are ready for crypto processing
* and call the matching crypto function in g_bde_crypt.c and schedule
* any writes needed. Read operations finish here by releasing the
* sector buffers and delivering the original bio request.
* 4) g_bde_write_done()
* Release sector buffers and deliver the original bio request.
*
* Because of the C-scope rules, the functions are almost perfectly in the
* opposite order in this source file.
*
* XXX: A switch to the hardware assisted crypto in src/sys/opencrypto will add
* XXX: additional states to this state-engine. Since no hardware available
* XXX: at this time has AES support, implementing this has been postponed
* XXX: until such time as it would result in a benefit.
*/
#include <sys/param.h>
#include <sys/bio.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/queue.h>
#include <sys/malloc.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <sys/proc.h>
#include <sys/kthread.h>
#include <crypto/rijndael/rijndael-api-fst.h>
#include <crypto/sha2/sha2.h>
#include <geom/geom.h>
#include <geom/bde/g_bde.h>
static void g_bde_delete_sector(struct g_bde_softc *wp, struct g_bde_sector *sp);
static struct g_bde_sector * g_bde_new_sector(struct g_bde_work *wp, u_int len);
static void g_bde_release_keysector(struct g_bde_work *wp);
static struct g_bde_sector *g_bde_get_keysector(struct g_bde_work *wp);
static int g_bde_start_read(struct g_bde_sector *sp);
static void g_bde_purge_sector(struct g_bde_softc *sc, int fraction);
/*
* Work item allocation.
*
* C++ would call these constructors and destructors.
*/
static u_int g_bde_nwork;
SYSCTL_UINT(_debug, OID_AUTO, gbde_nwork, CTLFLAG_RD, &g_bde_nwork, 0, "");
static MALLOC_DEFINE(M_GBDE, "gbde", "GBDE data structures");
static struct g_bde_work *
g_bde_new_work(struct g_bde_softc *sc)
{
struct g_bde_work *wp;
wp = malloc(sizeof *wp, M_GBDE, M_NOWAIT | M_ZERO);
if (wp == NULL)
return (wp);
wp->state = SETUP;
wp->softc = sc;
g_bde_nwork++;
sc->nwork++;
TAILQ_INSERT_TAIL(&sc->worklist, wp, list);
return (wp);
}
static void
g_bde_delete_work(struct g_bde_work *wp)
{
struct g_bde_softc *sc;
sc = wp->softc;
g_bde_nwork--;
sc->nwork--;
TAILQ_REMOVE(&sc->worklist, wp, list);
free(wp, M_GBDE);
}
/*
* Sector buffer allocation
*
* These two functions allocate and free back variable sized sector buffers
*/
static u_int g_bde_nsect;
SYSCTL_UINT(_debug, OID_AUTO, gbde_nsect, CTLFLAG_RD, &g_bde_nsect, 0, "");
static void
g_bde_delete_sector(struct g_bde_softc *sc, struct g_bde_sector *sp)
{
g_bde_nsect--;
sc->nsect--;
if (sp->malloc)
free(sp->data, M_GBDE);
free(sp, M_GBDE);
}
static struct g_bde_sector *
g_bde_new_sector(struct g_bde_work *wp, u_int len)
{
struct g_bde_sector *sp;
sp = malloc(sizeof *sp, M_GBDE, M_NOWAIT | M_ZERO);
if (sp == NULL)
return (sp);
if (len > 0) {
sp->data = malloc(len, M_GBDE, M_NOWAIT | M_ZERO);
if (sp->data == NULL) {
free(sp, M_GBDE);
return (NULL);
}
sp->malloc = 1;
}
g_bde_nsect++;
wp->softc->nsect++;
sp->size = len;
sp->softc = wp->softc;
sp->ref = 1;
sp->owner = wp;
sp->offset = wp->so;
sp->state = JUNK;
return (sp);
}
/*
* Skey sector cache.
*
* Nothing prevents two separate I/O requests from addressing the same zone
* and thereby needing the same skey sector. We therefore need to sequence
* I/O operations to the skey sectors. A certain amount of caching is also
* desirable, although the extent of benefit from this is not at this point
* determined.
*
* XXX: GEOM may be able to grow a generic caching facility at some point
* XXX: to support such needs.
*/
static u_int g_bde_ncache;
SYSCTL_UINT(_debug, OID_AUTO, gbde_ncache, CTLFLAG_RD, &g_bde_ncache, 0, "");
static void
g_bde_purge_one_sector(struct g_bde_softc *sc, struct g_bde_sector *sp)
{
g_trace(G_T_TOPOLOGY, "g_bde_purge_one_sector(%p, %p)", sc, sp);
if (sp->ref != 0)
return;
TAILQ_REMOVE(&sc->freelist, sp, list);
g_bde_ncache--;
sc->ncache--;
bzero(sp->data, sp->size);
g_bde_delete_sector(sc, sp);
}
static struct g_bde_sector *
g_bde_get_keysector(struct g_bde_work *wp)
{
struct g_bde_sector *sp;
struct g_bde_softc *sc;
off_t offset;
offset = wp->kso;
g_trace(G_T_TOPOLOGY, "g_bde_get_keysector(%p, %jd)", wp, (intmax_t)offset);
sc = wp->softc;
if (malloc_last_fail() < g_bde_ncache)
g_bde_purge_sector(sc, -1);
sp = TAILQ_FIRST(&sc->freelist);
if (sp != NULL && sp->ref == 0 && sp->used + 300 < time_uptime)
g_bde_purge_one_sector(sc, sp);
TAILQ_FOREACH(sp, &sc->freelist, list) {
if (sp->offset == offset)
break;
}
if (sp != NULL) {
sp->ref++;
KASSERT(sp->offset == offset, ("wrong offset"));
KASSERT(sp->softc == wp->softc, ("wrong softc"));
if (sp->ref == 1)
sp->owner = wp;
} else {
if (malloc_last_fail() < g_bde_ncache) {
TAILQ_FOREACH(sp, &sc->freelist, list)
if (sp->ref == 0)
break;
}
if (sp == NULL && !TAILQ_EMPTY(&sc->freelist))
sp = TAILQ_FIRST(&sc->freelist);
if (sp != NULL && sp->ref > 0)
sp = NULL;
if (sp == NULL) {
sp = g_bde_new_sector(wp, sc->sectorsize);
if (sp != NULL) {
g_bde_ncache++;
sc->ncache++;
TAILQ_INSERT_TAIL(&sc->freelist, sp, list);
sp->malloc = 2;
}
}
if (sp != NULL) {
sp->offset = offset;
sp->softc = wp->softc;
sp->ref = 1;
sp->owner = wp;
sp->state = JUNK;
sp->error = 0;
}
}
if (sp != NULL) {
TAILQ_REMOVE(&sc->freelist, sp, list);
TAILQ_INSERT_TAIL(&sc->freelist, sp, list);
sp->used = time_uptime;
}
wp->ksp = sp;
return(sp);
}
static void
g_bde_release_keysector(struct g_bde_work *wp)
{
struct g_bde_softc *sc;
struct g_bde_work *wp2;
struct g_bde_sector *sp;
sp = wp->ksp;
g_trace(G_T_TOPOLOGY, "g_bde_release_keysector(%p)", sp);
KASSERT(sp->malloc == 2, ("Wrong sector released"));
sc = sp->softc;
KASSERT(sc != NULL, ("NULL sp->softc"));
KASSERT(wp == sp->owner, ("Releasing, not owner"));
sp->owner = NULL;
wp->ksp = NULL;
sp->ref--;
if (sp->ref > 0) {
TAILQ_REMOVE(&sc->freelist, sp, list);
TAILQ_INSERT_TAIL(&sc->freelist, sp, list);
TAILQ_FOREACH(wp2, &sc->worklist, list) {
if (wp2->ksp == sp) {
KASSERT(wp2 != wp, ("Self-reowning"));
sp->owner = wp2;
wakeup(sp->softc);
break;
}
}
KASSERT(wp2 != NULL, ("Failed to pick up owner for %p\n", sp));
} else if (sp->error != 0) {
sp->offset = ~0;
sp->error = 0;
sp->state = JUNK;
}
TAILQ_REMOVE(&sc->freelist, sp, list);
TAILQ_INSERT_HEAD(&sc->freelist, sp, list);
}
static void
g_bde_purge_sector(struct g_bde_softc *sc, int fraction)
{
struct g_bde_sector *sp;
int n;
g_trace(G_T_TOPOLOGY, "g_bde_purge_sector(%p)", sc);
if (fraction > 0)
n = sc->ncache / fraction + 1;
else
n = g_bde_ncache - malloc_last_fail();
if (n < 0)
return;
if (n > sc->ncache)
n = sc->ncache;
while(n--) {
TAILQ_FOREACH(sp, &sc->freelist, list) {
if (sp->ref != 0)
continue;
TAILQ_REMOVE(&sc->freelist, sp, list);
g_bde_ncache--;
sc->ncache--;
bzero(sp->data, sp->size);
g_bde_delete_sector(sc, sp);
break;
}
}
}
static struct g_bde_sector *
g_bde_read_keysector(struct g_bde_softc *sc, struct g_bde_work *wp)
{
struct g_bde_sector *sp;
g_trace(G_T_TOPOLOGY, "g_bde_read_keysector(%p)", wp);
sp = g_bde_get_keysector(wp);
if (sp == NULL) {
g_bde_purge_sector(sc, -1);
sp = g_bde_get_keysector(wp);
}
if (sp == NULL)
return (sp);
if (sp->owner != wp)
return (sp);
if (sp->state == VALID)
return (sp);
if (g_bde_start_read(sp) == 0)
return (sp);
g_bde_release_keysector(wp);
return (NULL);
}
/*
* Contribute to the completion of the original bio request.
*
* We have no simple way to tell how many bits the original bio request has
* been segmented into, so the easiest way to determine when we can deliver
* it is to keep track of the number of bytes we have completed. We keep
* track of any errors underway and latch onto the first one.
*
* We always report "nothing done" in case of error, because random bits here
* and there may be completed and returning a number of completed bytes does
* not convey any useful information about which bytes they were. If some
* piece of broken code somewhere interprets this to mean that nothing has
* changed on the underlying media they deserve the lossage headed for them.
*
* A single mutex per g_bde instance is used to prevent contention.
*/
static void
g_bde_contribute(struct bio *bp, off_t bytes, int error)
{
g_trace(G_T_TOPOLOGY, "g_bde_contribute bp %p bytes %jd error %d",
bp, (intmax_t)bytes, error);
if (bp->bio_error == 0)
bp->bio_error = error;
bp->bio_completed += bytes;
KASSERT(bp->bio_completed <= bp->bio_length, ("Too large contribution"));
if (bp->bio_completed == bp->bio_length) {
if (bp->bio_error != 0)
bp->bio_completed = 0;
g_io_deliver(bp, bp->bio_error);
}
}
/*
* This is the common case "we're done with this work package" function
*/
static void
g_bde_work_done(struct g_bde_work *wp, int error)
{
g_bde_contribute(wp->bp, wp->length, error);
if (wp->sp != NULL)
g_bde_delete_sector(wp->softc, wp->sp);
if (wp->ksp != NULL)
g_bde_release_keysector(wp);
g_bde_delete_work(wp);
}
/*
* A write operation has finished. When we have all expected cows in the
* barn close the door and call it a day.
*/
static void
g_bde_write_done(struct bio *bp)
{
struct g_bde_sector *sp;
struct g_bde_work *wp;
struct g_bde_softc *sc;
sp = bp->bio_caller1;
sc = bp->bio_caller2;
mtx_lock(&sc->worklist_mutex);
KASSERT(sp != NULL, ("NULL sp"));
KASSERT(sc != NULL, ("NULL sc"));
KASSERT(sp->owner != NULL, ("NULL sp->owner"));
g_trace(G_T_TOPOLOGY, "g_bde_write_done(%p)", sp);
if (bp->bio_error == 0 && bp->bio_completed != sp->size)
bp->bio_error = EIO;
sp->error = bp->bio_error;
g_destroy_bio(bp);
wp = sp->owner;
if (wp->error == 0)
wp->error = sp->error;
if (wp->bp->bio_cmd == BIO_DELETE) {
KASSERT(sp == wp->sp, ("trashed delete op"));
g_bde_work_done(wp, wp->error);
mtx_unlock(&sc->worklist_mutex);
return;
}
KASSERT(wp->bp->bio_cmd == BIO_WRITE, ("Confused in g_bde_write_done()"));
KASSERT(sp == wp->sp || sp == wp->ksp, ("trashed write op"));
if (wp->sp == sp) {
g_bde_delete_sector(sc, wp->sp);
wp->sp = NULL;
} else {
sp->state = VALID;
}
if (wp->sp == NULL && wp->ksp != NULL && wp->ksp->state == VALID)
g_bde_work_done(wp, wp->error);
mtx_unlock(&sc->worklist_mutex);
return;
}
/*
* Send a write request for the given sector down the pipeline.
*/
static int
g_bde_start_write(struct g_bde_sector *sp)
{
struct bio *bp;
struct g_bde_softc *sc;
g_trace(G_T_TOPOLOGY, "g_bde_start_write(%p)", sp);
sc = sp->softc;
KASSERT(sc != NULL, ("NULL sc in g_bde_start_write"));
KASSERT(sp->owner != NULL, ("NULL sp->owner in g_bde_start_write"));
bp = g_new_bio();
if (bp == NULL)
return (ENOMEM);
bp->bio_cmd = BIO_WRITE;
bp->bio_offset = sp->offset;
bp->bio_data = sp->data;
bp->bio_length = sp->size;
bp->bio_done = g_bde_write_done;
bp->bio_caller1 = sp;
bp->bio_caller2 = sc;
sp->state = IO;
g_io_request(bp, sc->consumer);
return(0);
}
/*
* A read operation has finished. Mark the sector no longer iobusy and
* wake up the worker thread and let it do its thing.
*/
static void
g_bde_read_done(struct bio *bp)
{
struct g_bde_sector *sp;
struct g_bde_softc *sc;
sp = bp->bio_caller1;
g_trace(G_T_TOPOLOGY, "g_bde_read_done(%p)", sp);
sc = bp->bio_caller2;
mtx_lock(&sc->worklist_mutex);
if (bp->bio_error == 0 && bp->bio_completed != sp->size)
bp->bio_error = EIO;
sp->error = bp->bio_error;
if (sp->error == 0)
sp->state = VALID;
else
sp->state = JUNK;
wakeup(sc);
g_destroy_bio(bp);
mtx_unlock(&sc->worklist_mutex);
}
/*
* Send a read request for the given sector down the pipeline.
*/
static int
g_bde_start_read(struct g_bde_sector *sp)
{
struct bio *bp;
struct g_bde_softc *sc;
g_trace(G_T_TOPOLOGY, "g_bde_start_read(%p)", sp);
sc = sp->softc;
KASSERT(sc != NULL, ("Null softc in sp %p", sp));
bp = g_new_bio();
if (bp == NULL)
return (ENOMEM);
bp->bio_cmd = BIO_READ;
bp->bio_offset = sp->offset;
bp->bio_data = sp->data;
bp->bio_length = sp->size;
bp->bio_done = g_bde_read_done;
bp->bio_caller1 = sp;
bp->bio_caller2 = sc;
sp->state = IO;
g_io_request(bp, sc->consumer);
return(0);
}
/*
* The worker thread.
*
* The up/down path of GEOM is not allowed to sleep or do any major work
* so we use this thread to do the actual crypto operations and to push
* the state engine onwards.
*
* XXX: if we switch to the src/sys/opencrypt hardware assisted encryption
* XXX: using a thread here is probably not needed.
*/
void
g_bde_worker(void *arg)
{
struct g_bde_softc *sc;
struct g_bde_work *wp, *twp;
struct g_geom *gp;
int restart, error;
gp = arg;
sc = gp->softc;
mtx_lock(&sc->worklist_mutex);
for (;;) {
restart = 0;
g_trace(G_T_TOPOLOGY, "g_bde_worker scan");
TAILQ_FOREACH_SAFE(wp, &sc->worklist, list, twp) {
KASSERT(wp != NULL, ("NULL wp"));
KASSERT(wp->softc != NULL, ("NULL wp->softc"));
if (wp->state != WAIT)
continue; /* Not interesting here */
KASSERT(wp->bp != NULL, ("NULL wp->bp"));
KASSERT(wp->sp != NULL, ("NULL wp->sp"));
if (wp->ksp != NULL) {
if (wp->ksp->owner != wp)
continue;
if (wp->ksp->state == IO)
continue;
KASSERT(wp->ksp->state == VALID,
("Illegal sector state (%d)",
wp->ksp->state));
}
if (wp->bp->bio_cmd == BIO_READ && wp->sp->state == IO)
continue;
if (wp->ksp != NULL && wp->ksp->error != 0) {
g_bde_work_done(wp, wp->ksp->error);
continue;
}
switch(wp->bp->bio_cmd) {
case BIO_READ:
if (wp->ksp == NULL) {
KASSERT(wp->error != 0,
("BIO_READ, no ksp and no error"));
g_bde_work_done(wp, wp->error);
break;
}
if (wp->sp->error != 0) {
g_bde_work_done(wp, wp->sp->error);
break;
}
mtx_unlock(&sc->worklist_mutex);
g_bde_crypt_read(wp);
mtx_lock(&sc->worklist_mutex);
restart++;
g_bde_work_done(wp, wp->sp->error);
break;
case BIO_WRITE:
wp->state = FINISH;
KASSERT(wp->sp->owner == wp,
("Write not owner sp"));
KASSERT(wp->ksp->owner == wp,
("Write not owner ksp"));
mtx_unlock(&sc->worklist_mutex);
g_bde_crypt_write(wp);
mtx_lock(&sc->worklist_mutex);
restart++;
error = g_bde_start_write(wp->sp);
if (error) {
g_bde_work_done(wp, error);
break;
}
error = g_bde_start_write(wp->ksp);
if (wp->error != 0)
wp->error = error;
break;
case BIO_DELETE:
wp->state = FINISH;
mtx_unlock(&sc->worklist_mutex);
g_bde_crypt_delete(wp);
mtx_lock(&sc->worklist_mutex);
restart++;
g_bde_start_write(wp->sp);
break;
}
if (restart)
break;
}
if (!restart) {
/*
* We don't look for our death-warrant until we are
* idle. Shouldn't make a difference in practice.
*/
if (sc->dead)
break;
g_trace(G_T_TOPOLOGY, "g_bde_worker sleep");
error = msleep(sc, &sc->worklist_mutex,
PRIBIO, "-", hz);
if (error == EWOULDBLOCK) {
/*
* Lose our skey cache in an orderly fashion.
* The exact rate can be tuned to be less
* aggressive if this is desirable. 10% per
* second means that the cache is gone in a
* few minutes.
*/
g_bde_purge_sector(sc, 10);
}
}
}
g_trace(G_T_TOPOLOGY, "g_bde_worker die");
g_bde_purge_sector(sc, 1);
KASSERT(sc->nwork == 0, ("Dead but %d work remaining", sc->nwork));
KASSERT(sc->ncache == 0, ("Dead but %d cache remaining", sc->ncache));
KASSERT(sc->nsect == 0, ("Dead but %d sect remaining", sc->nsect));
mtx_unlock(&sc->worklist_mutex);
sc->dead = 2;
wakeup(sc);
kproc_exit(0);
}
/*
* g_bde_start1 has chopped the incoming request up so all the requests
* we see here are inside a single zone. Map the data and key locations
* grab the buffers we need and fire off the first volley of read requests.
*/
static void
g_bde_start2(struct g_bde_work *wp)
{
struct g_bde_softc *sc;
KASSERT(wp != NULL, ("NULL wp in g_bde_start2"));
KASSERT(wp->softc != NULL, ("NULL wp->softc"));
g_trace(G_T_TOPOLOGY, "g_bde_start2(%p)", wp);
sc = wp->softc;
switch (wp->bp->bio_cmd) {
case BIO_READ:
wp->sp = g_bde_new_sector(wp, 0);
if (wp->sp == NULL) {
g_bde_work_done(wp, ENOMEM);
return;
}
wp->sp->size = wp->length;
wp->sp->data = wp->data;
if (g_bde_start_read(wp->sp) != 0) {
g_bde_work_done(wp, ENOMEM);
return;
}
g_bde_read_keysector(sc, wp);
if (wp->ksp == NULL)
wp->error = ENOMEM;
break;
case BIO_DELETE:
wp->sp = g_bde_new_sector(wp, wp->length);
if (wp->sp == NULL) {
g_bde_work_done(wp, ENOMEM);
return;
}
break;
case BIO_WRITE:
wp->sp = g_bde_new_sector(wp, wp->length);
if (wp->sp == NULL) {
g_bde_work_done(wp, ENOMEM);
return;
}
g_bde_read_keysector(sc, wp);
if (wp->ksp == NULL) {
g_bde_work_done(wp, ENOMEM);
return;
}
break;
default:
KASSERT(0 == 1,
("Wrong bio_cmd %d in g_bde_start2", wp->bp->bio_cmd));
}
wp->state = WAIT;
wakeup(sc);
}
/*
* Create a sequence of work structures, and have g_bde_map_sector() determine
* how long they each can be. Feed them to g_bde_start2().
*/
void
g_bde_start1(struct bio *bp)
{
struct g_bde_softc *sc;
struct g_bde_work *wp;
off_t done;
sc = bp->bio_to->geom->softc;
bp->bio_driver1 = sc;
mtx_lock(&sc->worklist_mutex);
for(done = 0; done < bp->bio_length; ) {
wp = g_bde_new_work(sc);
if (wp != NULL) {
wp->bp = bp;
wp->offset = bp->bio_offset + done;
wp->data = bp->bio_data + done;
wp->length = bp->bio_length - done;
g_bde_map_sector(wp);
done += wp->length;
g_bde_start2(wp);
}
if (wp == NULL || bp->bio_error != 0) {
g_bde_contribute(bp, bp->bio_length - done, ENOMEM);
break;
}
}
mtx_unlock(&sc->worklist_mutex);
return;
}