[PATCH 2/2] staging: lustre: libcfs: remove workitem code.

From: NeilBrown
Date: Wed Jan 10 2018 - 23:08:08 EST

There are now no users. workqueues are doing the job
that this used to do.

Signed-off-by: NeilBrown <neilb@xxxxxxxx>
---
.../staging/lustre/include/linux/libcfs/libcfs.h | 1
.../lustre/include/linux/libcfs/libcfs_workitem.h | 104 ----
drivers/staging/lustre/lnet/libcfs/Makefile | 2
drivers/staging/lustre/lnet/libcfs/module.c | 11
drivers/staging/lustre/lnet/libcfs/workitem.c | 466 --------------------
5 files changed, 2 insertions(+), 582 deletions(-)
delete mode 100644 drivers/staging/lustre/include/linux/libcfs/libcfs_workitem.h
delete mode 100644 drivers/staging/lustre/lnet/libcfs/workitem.c

diff --git a/drivers/staging/lustre/include/linux/libcfs/libcfs.h b/drivers/staging/lustre/include/linux/libcfs/libcfs.h
index 5bd7bee0624b..ca3472cc952f 100644
--- a/drivers/staging/lustre/include/linux/libcfs/libcfs.h
+++ b/drivers/staging/lustre/include/linux/libcfs/libcfs.h
@@ -45,7 +45,6 @@
#include <linux/libcfs/libcfs_prim.h>
#include <linux/libcfs/libcfs_time.h>
#include <linux/libcfs/libcfs_string.h>
-#include <linux/libcfs/libcfs_workitem.h>
#include <linux/libcfs/libcfs_hash.h>
#include <linux/libcfs/libcfs_fail.h>
#include <linux/libcfs/curproc.h>
diff --git a/drivers/staging/lustre/include/linux/libcfs/libcfs_workitem.h b/drivers/staging/lustre/include/linux/libcfs/libcfs_workitem.h
deleted file mode 100644
index ddaca33a13ac..000000000000
--- a/drivers/staging/lustre/include/linux/libcfs/libcfs_workitem.h
+++ /dev/null
@@ -1,104 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * GPL HEADER START
- *
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 only,
- * as published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful, but
- * WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * General Public License version 2 for more details (a copy is included
- * in the LICENSE file that accompanied this code).
- *
- * You should have received a copy of the GNU General Public License
- * version 2 along with this program; If not, see
- * http://www.gnu.org/licenses/gpl-2.0.html
- *
- * GPL HEADER END
- */
-/*
- * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
- * Use is subject to license terms.
- *
- * Copyright (c) 2012, Intel Corporation.
- */
-/*
- * This file is part of Lustre, http://www.lustre.org/
- * Lustre is a trademark of Sun Microsystems, Inc.
- *
- * libcfs/include/libcfs/libcfs_workitem.h
- *
- * Author: Isaac Huang <he.h.huang@xxxxxxxxxx>
- * Liang Zhen <zhen.liang@xxxxxxx>
- *
- * A workitems is deferred work with these semantics:
- * - a workitem always runs in thread context.
- * - a workitem can be concurrent with other workitems but is strictly
- * serialized with respect to itself.
- * - no CPU affinity, a workitem does not necessarily run on the same CPU
- * that schedules it. However, this might change in the future.
- * - if a workitem is scheduled again before it has a chance to run, it
- * runs only once.
- * - if a workitem is scheduled while it runs, it runs again after it
- * completes; this ensures that events occurring while other events are
- * being processed receive due attention. This behavior also allows a
- * workitem to reschedule itself.
- *
- * Usage notes:
- * - a workitem can sleep but it should be aware of how that sleep might
- * affect others.
- * - a workitem runs inside a kernel thread so there's no user space to access.
- * - do not use a workitem if the scheduling latency can't be tolerated.
- *
- * When wi_action returns non-zero, it means the workitem has either been
- * freed or reused and workitem scheduler won't touch it any more.
- */
-
-#ifndef __LIBCFS_WORKITEM_H__
-#define __LIBCFS_WORKITEM_H__
-
-struct cfs_wi_sched;
-
-void cfs_wi_sched_destroy(struct cfs_wi_sched *sched);
-int cfs_wi_sched_create(char *name, struct cfs_cpt_table *cptab, int cpt,
- int nthrs, struct cfs_wi_sched **sched_pp);
-
-struct cfs_workitem;
-
-typedef int (*cfs_wi_action_t) (struct cfs_workitem *);
-struct cfs_workitem {
- /** chain on runq or rerunq */
- struct list_head wi_list;
- /** working function */
- cfs_wi_action_t wi_action;
- /** in running */
- unsigned short wi_running:1;
- /** scheduled */
- unsigned short wi_scheduled:1;
-};
-
-static inline void
-cfs_wi_init(struct cfs_workitem *wi, cfs_wi_action_t action)
-{
- INIT_LIST_HEAD(&wi->wi_list);
-
- wi->wi_running = 0;
- wi->wi_scheduled = 0;
- wi->wi_action = action;
-}
-
-void cfs_wi_schedule(struct cfs_wi_sched *sched, struct cfs_workitem *wi);
-int cfs_wi_deschedule(struct cfs_wi_sched *sched, struct cfs_workitem *wi);
-void cfs_wi_exit(struct cfs_wi_sched *sched, struct cfs_workitem *wi);
-
-int cfs_wi_startup(void);
-void cfs_wi_shutdown(void);
-
-/** # workitem scheduler loops before reschedule */
-#define CFS_WI_RESCHED 128
-
-#endif /* __LIBCFS_WORKITEM_H__ */
diff --git a/drivers/staging/lustre/lnet/libcfs/Makefile b/drivers/staging/lustre/lnet/libcfs/Makefile
index db5b36cc3e6d..730f2c675047 100644
--- a/drivers/staging/lustre/lnet/libcfs/Makefile
+++ b/drivers/staging/lustre/lnet/libcfs/Makefile
@@ -15,7 +15,7 @@ libcfs-linux-objs += linux-mem.o
libcfs-linux-objs := $(addprefix linux/,$(libcfs-linux-objs))

libcfs-all-objs := debug.o fail.o module.o tracefile.o \
- libcfs_string.o hash.o workitem.o \
+ libcfs_string.o hash.o \
libcfs_cpu.o libcfs_mem.o libcfs_lock.o

libcfs-objs := $(libcfs-linux-objs) $(libcfs-all-objs)
diff --git a/drivers/staging/lustre/lnet/libcfs/module.c b/drivers/staging/lustre/lnet/libcfs/module.c
index 555f47651730..a03f924f1d7c 100644
--- a/drivers/staging/lustre/lnet/libcfs/module.c
+++ b/drivers/staging/lustre/lnet/libcfs/module.c
@@ -547,12 +547,6 @@ static int libcfs_init(void)
goto cleanup_cpu;
}

- rc = cfs_wi_startup();
- if (rc) {
- CERROR("initialize workitem: error %d\n", rc);
- goto cleanup_deregister;
- }
-
cfs_rehash_wq = alloc_workqueue("cfs_rh", WQ_SYSFS, 4);
if (!cfs_rehash_wq) {
CERROR("Failed to start rehash workqueue.\n");
@@ -563,15 +557,13 @@ static int libcfs_init(void)
rc = cfs_crypto_register();
if (rc) {
CERROR("cfs_crypto_register: error %d\n", rc);
- goto cleanup_wi;
+ goto cleanup_deregister;
}

lustre_insert_debugfs(lnet_table, lnet_debugfs_symlinks);

CDEBUG(D_OTHER, "portals setup OK\n");
return 0;
- cleanup_wi:
- cfs_wi_shutdown();
cleanup_deregister:
misc_deregister(&libcfs_dev);
cleanup_cpu:
@@ -593,7 +585,6 @@ static void libcfs_exit(void)
}

cfs_crypto_unregister();
- cfs_wi_shutdown();

misc_deregister(&libcfs_dev);

diff --git a/drivers/staging/lustre/lnet/libcfs/workitem.c b/drivers/staging/lustre/lnet/libcfs/workitem.c
deleted file mode 100644
index 74a9595dc730..000000000000
--- a/drivers/staging/lustre/lnet/libcfs/workitem.c
+++ /dev/null
@@ -1,466 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * GPL HEADER START
- *
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 only,
- * as published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful, but
- * WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * General Public License version 2 for more details (a copy is included
- * in the LICENSE file that accompanied this code).
- *
- * You should have received a copy of the GNU General Public License
- * version 2 along with this program; If not, see
- * http://www.gnu.org/licenses/gpl-2.0.html
- *
- * GPL HEADER END
- */
-/*
- * Copyright (c) 2007, 2010, Oracle and/or its affiliates. All rights reserved.
- * Use is subject to license terms.
- *
- * Copyright (c) 2011, 2012, Intel Corporation.
- */
-/*
- * This file is part of Lustre, http://www.lustre.org/
- * Lustre is a trademark of Sun Microsystems, Inc.
- *
- * libcfs/libcfs/workitem.c
- *
- * Author: Isaac Huang <isaac@xxxxxxxxxxxxx>
- * Liang Zhen <zhen.liang@xxxxxxx>
- */
-
-#define DEBUG_SUBSYSTEM S_LNET
-
-#include <linux/libcfs/libcfs.h>
-
-#define CFS_WS_NAME_LEN 16
-
-struct cfs_wi_sched {
- /* chain on global list */
- struct list_head ws_list;
- /** serialised workitems */
- spinlock_t ws_lock;
- /** where schedulers sleep */
- wait_queue_head_t ws_waitq;
- /** concurrent workitems */
- struct list_head ws_runq;
- /**
- * rescheduled running-workitems, a workitem can be rescheduled
- * while running in wi_action(), but we don't to execute it again
- * unless it returns from wi_action(), so we put it on ws_rerunq
- * while rescheduling, and move it to runq after it returns
- * from wi_action()
- */
- struct list_head ws_rerunq;
- /** CPT-table for this scheduler */
- struct cfs_cpt_table *ws_cptab;
- /** CPT id for affinity */
- int ws_cpt;
- /** number of scheduled workitems */
- int ws_nscheduled;
- /** started scheduler thread, protected by cfs_wi_data::wi_glock */
- unsigned int ws_nthreads:30;
- /** shutting down, protected by cfs_wi_data::wi_glock */
- unsigned int ws_stopping:1;
- /** serialize starting thread, protected by cfs_wi_data::wi_glock */
- unsigned int ws_starting:1;
- /** scheduler name */
- char ws_name[CFS_WS_NAME_LEN];
-};
-
-static struct cfs_workitem_data {
- /** serialize */
- spinlock_t wi_glock;
- /** list of all schedulers */
- struct list_head wi_scheds;
- /** WI module is initialized */
- int wi_init;
- /** shutting down the whole WI module */
- int wi_stopping;
-} cfs_wi_data;
-
-static inline int
-cfs_wi_sched_cansleep(struct cfs_wi_sched *sched)
-{
- spin_lock(&sched->ws_lock);
- if (sched->ws_stopping) {
- spin_unlock(&sched->ws_lock);
- return 0;
- }
-
- if (!list_empty(&sched->ws_runq)) {
- spin_unlock(&sched->ws_lock);
- return 0;
- }
- spin_unlock(&sched->ws_lock);
- return 1;
-}
-
-/* XXX:
- * 0. it only works when called from wi->wi_action.
- * 1. when it returns no one shall try to schedule the workitem.
- */
-void
-cfs_wi_exit(struct cfs_wi_sched *sched, struct cfs_workitem *wi)
-{
- LASSERT(!in_interrupt()); /* because we use plain spinlock */
- LASSERT(!sched->ws_stopping);
-
- spin_lock(&sched->ws_lock);
-
- LASSERT(wi->wi_running);
- if (wi->wi_scheduled) { /* cancel pending schedules */
- LASSERT(!list_empty(&wi->wi_list));
- list_del_init(&wi->wi_list);
-
- LASSERT(sched->ws_nscheduled > 0);
- sched->ws_nscheduled--;
- }
-
- LASSERT(list_empty(&wi->wi_list));
-
- wi->wi_scheduled = 1; /* LBUG future schedule attempts */
- spin_unlock(&sched->ws_lock);
-}
-EXPORT_SYMBOL(cfs_wi_exit);
-
-/**
- * cancel schedule request of workitem \a wi
- */
-int
-cfs_wi_deschedule(struct cfs_wi_sched *sched, struct cfs_workitem *wi)
-{
- int rc;
-
- LASSERT(!in_interrupt()); /* because we use plain spinlock */
- LASSERT(!sched->ws_stopping);
-
- /*
- * return 0 if it's running already, otherwise return 1, which
- * means the workitem will not be scheduled and will not have
- * any race with wi_action.
- */
- spin_lock(&sched->ws_lock);
-
- rc = !(wi->wi_running);
-
- if (wi->wi_scheduled) { /* cancel pending schedules */
- LASSERT(!list_empty(&wi->wi_list));
- list_del_init(&wi->wi_list);
-
- LASSERT(sched->ws_nscheduled > 0);
- sched->ws_nscheduled--;
-
- wi->wi_scheduled = 0;
- }
-
- LASSERT(list_empty(&wi->wi_list));
-
- spin_unlock(&sched->ws_lock);
- return rc;
-}
-EXPORT_SYMBOL(cfs_wi_deschedule);
-
-/*
- * Workitem scheduled with (serial == 1) is strictly serialised not only with
- * itself, but also with others scheduled this way.
- *
- * Now there's only one static serialised queue, but in the future more might
- * be added, and even dynamic creation of serialised queues might be supported.
- */
-void
-cfs_wi_schedule(struct cfs_wi_sched *sched, struct cfs_workitem *wi)
-{
- LASSERT(!in_interrupt()); /* because we use plain spinlock */
- LASSERT(!sched->ws_stopping);
-
- spin_lock(&sched->ws_lock);
-
- if (!wi->wi_scheduled) {
- LASSERT(list_empty(&wi->wi_list));
-
- wi->wi_scheduled = 1;
- sched->ws_nscheduled++;
- if (!wi->wi_running) {
- list_add_tail(&wi->wi_list, &sched->ws_runq);
- wake_up(&sched->ws_waitq);
- } else {
- list_add(&wi->wi_list, &sched->ws_rerunq);
- }
- }
-
- LASSERT(!list_empty(&wi->wi_list));
- spin_unlock(&sched->ws_lock);
-}
-EXPORT_SYMBOL(cfs_wi_schedule);
-
-static int cfs_wi_scheduler(void *arg)
-{
- struct cfs_wi_sched *sched = (struct cfs_wi_sched *)arg;
-
- cfs_block_allsigs();
-
- /* CPT affinity scheduler? */
- if (sched->ws_cptab)
- if (cfs_cpt_bind(sched->ws_cptab, sched->ws_cpt))
- CWARN("Unable to bind %s on CPU partition %d\n",
- sched->ws_name, sched->ws_cpt);
-
- spin_lock(&cfs_wi_data.wi_glock);
-
- LASSERT(sched->ws_starting == 1);
- sched->ws_starting--;
- sched->ws_nthreads++;
-
- spin_unlock(&cfs_wi_data.wi_glock);
-
- spin_lock(&sched->ws_lock);
-
- while (!sched->ws_stopping) {
- int nloops = 0;
- int rc;
- struct cfs_workitem *wi;
-
- while (!list_empty(&sched->ws_runq) &&
- nloops < CFS_WI_RESCHED) {
- wi = list_entry(sched->ws_runq.next,
- struct cfs_workitem, wi_list);
- LASSERT(wi->wi_scheduled && !wi->wi_running);
-
- list_del_init(&wi->wi_list);
-
- LASSERT(sched->ws_nscheduled > 0);
- sched->ws_nscheduled--;
-
- wi->wi_running = 1;
- wi->wi_scheduled = 0;
-
- spin_unlock(&sched->ws_lock);
- nloops++;
-
- rc = (*wi->wi_action)(wi);
-
- spin_lock(&sched->ws_lock);
- if (rc) /* WI should be dead, even be freed! */
- continue;
-
- wi->wi_running = 0;
- if (list_empty(&wi->wi_list))
- continue;
-
- LASSERT(wi->wi_scheduled);
- /* wi is rescheduled, should be on rerunq now, we
- * move it to runq so it can run action now
- */
- list_move_tail(&wi->wi_list, &sched->ws_runq);
- }
-
- if (!list_empty(&sched->ws_runq)) {
- spin_unlock(&sched->ws_lock);
- /* don't sleep because some workitems still
- * expect me to come back soon
- */
- cond_resched();
- spin_lock(&sched->ws_lock);
- continue;
- }
-
- spin_unlock(&sched->ws_lock);
- rc = wait_event_interruptible_exclusive(sched->ws_waitq,
- !cfs_wi_sched_cansleep(sched));
- spin_lock(&sched->ws_lock);
- }
-
- spin_unlock(&sched->ws_lock);
-
- spin_lock(&cfs_wi_data.wi_glock);
- sched->ws_nthreads--;
- spin_unlock(&cfs_wi_data.wi_glock);
-
- return 0;
-}
-
-void
-cfs_wi_sched_destroy(struct cfs_wi_sched *sched)
-{
- int i;
-
- LASSERT(cfs_wi_data.wi_init);
- LASSERT(!cfs_wi_data.wi_stopping);
-
- spin_lock(&cfs_wi_data.wi_glock);
- if (sched->ws_stopping) {
- CDEBUG(D_INFO, "%s is in progress of stopping\n",
- sched->ws_name);
- spin_unlock(&cfs_wi_data.wi_glock);
- return;
- }
-
- LASSERT(!list_empty(&sched->ws_list));
- sched->ws_stopping = 1;
-
- spin_unlock(&cfs_wi_data.wi_glock);
-
- i = 2;
- wake_up_all(&sched->ws_waitq);
-
- spin_lock(&cfs_wi_data.wi_glock);
- while (sched->ws_nthreads > 0) {
- CDEBUG(is_power_of_2(++i) ? D_WARNING : D_NET,
- "waiting for %d threads of WI sched[%s] to terminate\n",
- sched->ws_nthreads, sched->ws_name);
-
- spin_unlock(&cfs_wi_data.wi_glock);
- set_current_state(TASK_UNINTERRUPTIBLE);
- schedule_timeout(cfs_time_seconds(1) / 20);
- spin_lock(&cfs_wi_data.wi_glock);
- }
-
- list_del(&sched->ws_list);
-
- spin_unlock(&cfs_wi_data.wi_glock);
- LASSERT(!sched->ws_nscheduled);
-
- kfree(sched);
-}
-EXPORT_SYMBOL(cfs_wi_sched_destroy);
-
-int
-cfs_wi_sched_create(char *name, struct cfs_cpt_table *cptab,
- int cpt, int nthrs, struct cfs_wi_sched **sched_pp)
-{
- struct cfs_wi_sched *sched;
- int rc;
-
- LASSERT(cfs_wi_data.wi_init);
- LASSERT(!cfs_wi_data.wi_stopping);
- LASSERT(!cptab || cpt == CFS_CPT_ANY ||
- (cpt >= 0 && cpt < cfs_cpt_number(cptab)));
-
- sched = kzalloc(sizeof(*sched), GFP_NOFS);
- if (!sched)
- return -ENOMEM;
-
- if (strlen(name) > sizeof(sched->ws_name) - 1) {
- kfree(sched);
- return -E2BIG;
- }
- strncpy(sched->ws_name, name, sizeof(sched->ws_name));
-
- sched->ws_cptab = cptab;
- sched->ws_cpt = cpt;
-
- spin_lock_init(&sched->ws_lock);
- init_waitqueue_head(&sched->ws_waitq);
- INIT_LIST_HEAD(&sched->ws_runq);
- INIT_LIST_HEAD(&sched->ws_rerunq);
- INIT_LIST_HEAD(&sched->ws_list);
-
- rc = 0;
- while (nthrs > 0) {
- char name[16];
- struct task_struct *task;
-
- spin_lock(&cfs_wi_data.wi_glock);
- while (sched->ws_starting > 0) {
- spin_unlock(&cfs_wi_data.wi_glock);
- schedule();
- spin_lock(&cfs_wi_data.wi_glock);
- }
-
- sched->ws_starting++;
- spin_unlock(&cfs_wi_data.wi_glock);
-
- if (sched->ws_cptab && sched->ws_cpt >= 0) {
- snprintf(name, sizeof(name), "%s_%02d_%02u",
- sched->ws_name, sched->ws_cpt,
- sched->ws_nthreads);
- } else {
- snprintf(name, sizeof(name), "%s_%02u",
- sched->ws_name, sched->ws_nthreads);
- }
-
- task = kthread_run(cfs_wi_scheduler, sched, "%s", name);
- if (!IS_ERR(task)) {
- nthrs--;
- continue;
- }
- rc = PTR_ERR(task);
-
- CERROR("Failed to create thread for WI scheduler %s: %d\n",
- name, rc);
-
- spin_lock(&cfs_wi_data.wi_glock);
-
- /* make up for cfs_wi_sched_destroy */
- list_add(&sched->ws_list, &cfs_wi_data.wi_scheds);
- sched->ws_starting--;
-
- spin_unlock(&cfs_wi_data.wi_glock);
-
- cfs_wi_sched_destroy(sched);
- return rc;
- }
- spin_lock(&cfs_wi_data.wi_glock);
- list_add(&sched->ws_list, &cfs_wi_data.wi_scheds);
- spin_unlock(&cfs_wi_data.wi_glock);
-
- *sched_pp = sched;
- return 0;
-}
-EXPORT_SYMBOL(cfs_wi_sched_create);
-
-int
-cfs_wi_startup(void)
-{
- memset(&cfs_wi_data, 0, sizeof(cfs_wi_data));
-
- spin_lock_init(&cfs_wi_data.wi_glock);
- INIT_LIST_HEAD(&cfs_wi_data.wi_scheds);
- cfs_wi_data.wi_init = 1;
-
- return 0;
-}
-
-void
-cfs_wi_shutdown(void)
-{
- struct cfs_wi_sched *sched;
- struct cfs_wi_sched *temp;
-
- spin_lock(&cfs_wi_data.wi_glock);
- cfs_wi_data.wi_stopping = 1;
- spin_unlock(&cfs_wi_data.wi_glock);
-
- /* nobody should contend on this list */
- list_for_each_entry(sched, &cfs_wi_data.wi_scheds, ws_list) {
- sched->ws_stopping = 1;
- wake_up_all(&sched->ws_waitq);
- }
-
- list_for_each_entry(sched, &cfs_wi_data.wi_scheds, ws_list) {
- spin_lock(&cfs_wi_data.wi_glock);
-
- while (sched->ws_nthreads) {
- spin_unlock(&cfs_wi_data.wi_glock);
- set_current_state(TASK_UNINTERRUPTIBLE);
- schedule_timeout(cfs_time_seconds(1) / 20);
- spin_lock(&cfs_wi_data.wi_glock);
- }
- spin_unlock(&cfs_wi_data.wi_glock);
- }
- list_for_each_entry_safe(sched, temp, &cfs_wi_data.wi_scheds, ws_list) {
- list_del(&sched->ws_list);
- kfree(sched);
- }
-
- cfs_wi_data.wi_stopping = 0;
- cfs_wi_data.wi_init = 0;
-}