staging: unisys: visorbus: remove periodic_work.h/.c

These files were made no-longer-necessary by recent commits.
Signed-off-by: Tim Sell <Timothy.Sell@unisys.com>
Signed-off-by: David Kershner <david.kershner@unisys.com>
Acked-By: Neil Horman <nhorman@tuxdriver.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/unisys/include/periodic_work.h

-/* periodic_work.h
- *
- * Copyright (C) 2010 - 2013 UNISYS CORPORATION
- * All rights reserved.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or (at
- * your option) any later version.
- *
- * 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, GOOD TITLE or
- * NON INFRINGEMENT.  See the GNU General Public License for more
- * details.
- */
-
-#ifndef __PERIODIC_WORK_H__
-#define __PERIODIC_WORK_H__
-
-#include <linux/seq_file.h>
-#include <linux/slab.h>
-
-/* PERIODIC_WORK an opaque structure to users.
- * Fields are declared only in the implementation .c files.
- */
-struct periodic_work;
-
-struct periodic_work *
-visor_periodic_work_create(ulong jiffy_interval,
-			   struct workqueue_struct *workqueue,
-			   void (*workfunc)(void *),
-			   void *workfuncarg,
-			   const char *devnam);
-void visor_periodic_work_destroy(struct periodic_work *pw);
-bool visor_periodic_work_nextperiod(struct periodic_work *pw);
-bool visor_periodic_work_start(struct periodic_work *pw);
-bool visor_periodic_work_stop(struct periodic_work *pw);
-
-#endif

drivers/staging/unisys/visorbus/Makefile

@@ -7,6 +7,5 @@ obj-$(CONFIG_UNISYS_VISORBUS)	+= visorbus.o
 visorbus-y := visorbus_main.o
 visorbus-y += visorchannel.o
 visorbus-y += visorchipset.o
-visorbus-y += periodic_work.o
 
 ccflags-y += -Idrivers/staging/unisys/include

drivers/staging/unisys/visorbus/periodic_work.c

-/* periodic_work.c
- *
- * Copyright (C) 2010 - 2015 UNISYS CORPORATION
- * All rights reserved.
- *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms and conditions of the GNU General Public License,
- * version 2, 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, GOOD TITLE or
- * NON INFRINGEMENT.  See the GNU General Public License for more
- * details.
- */
-
-/*
- *  Helper functions to schedule periodic work in Linux kernel mode.
- */
-#include <linux/sched.h>
-
-#include "periodic_work.h"
-
-#define MYDRVNAME "periodic_work"
-
-struct periodic_work {
-	rwlock_t lock;
-	struct delayed_work work;
-	void (*workfunc)(void *);
-	void *workfuncarg;
-	bool is_scheduled;
-	bool want_to_stop;
-	ulong jiffy_interval;
-	struct workqueue_struct *workqueue;
-	const char *devnam;
-};
-
-static void periodic_work_func(struct work_struct *work)
-{
-	struct periodic_work *pw;
-
-	pw = container_of(work, struct periodic_work, work.work);
-	(*pw->workfunc)(pw->workfuncarg);
-}
-
-struct periodic_work
-*visor_periodic_work_create(ulong jiffy_interval,
-			    struct workqueue_struct *workqueue,
-			    void (*workfunc)(void *),
-			    void *workfuncarg,
-			    const char *devnam)
-{
-	struct periodic_work *pw;
-
-	pw = kzalloc(sizeof(*pw), GFP_KERNEL | __GFP_NORETRY);
-	if (!pw)
-		return NULL;
-
-	rwlock_init(&pw->lock);
-	pw->jiffy_interval = jiffy_interval;
-	pw->workqueue = workqueue;
-	pw->workfunc = workfunc;
-	pw->workfuncarg = workfuncarg;
-	pw->devnam = devnam;
-	return pw;
-}
-EXPORT_SYMBOL_GPL(visor_periodic_work_create);
-
-void visor_periodic_work_destroy(struct periodic_work *pw)
-{
-	kfree(pw);
-}
-EXPORT_SYMBOL_GPL(visor_periodic_work_destroy);
-
-/** Call this from your periodic work worker function to schedule the next
- *  call.
- *  If this function returns false, there was a failure and the
- *  periodic work is no longer scheduled
- */
-bool visor_periodic_work_nextperiod(struct periodic_work *pw)
-{
-	bool rc = false;
-
-	write_lock(&pw->lock);
-	if (pw->want_to_stop) {
-		pw->is_scheduled = false;
-		pw->want_to_stop = false;
-		rc = true;  /* yes, true; see visor_periodic_work_stop() */
-		goto unlock;
-	} else if (!queue_delayed_work(pw->workqueue, &pw->work,
-				       pw->jiffy_interval)) {
-		pw->is_scheduled = false;
-		rc = false;
-		goto unlock;
-	}
-	rc = true;
-unlock:
-	write_unlock(&pw->lock);
-	return rc;
-}
-EXPORT_SYMBOL_GPL(visor_periodic_work_nextperiod);
-
-/** This function returns true iff new periodic work was actually started.
- *  If this function returns false, then no work was started
- *  (either because it was already started, or because of a failure).
- */
-bool visor_periodic_work_start(struct periodic_work *pw)
-{
-	bool rc = false;
-
-	write_lock(&pw->lock);
-	if (pw->is_scheduled) {
-		rc = false;
-		goto unlock;
-	}
-	if (pw->want_to_stop) {
-		rc = false;
-		goto unlock;
-	}
-	INIT_DELAYED_WORK(&pw->work, &periodic_work_func);
-	if (!queue_delayed_work(pw->workqueue, &pw->work,
-				pw->jiffy_interval)) {
-		rc = false;
-		goto unlock;
-	}
-	pw->is_scheduled = true;
-	rc = true;
-unlock:
-	write_unlock(&pw->lock);
-	return rc;
-}
-EXPORT_SYMBOL_GPL(visor_periodic_work_start);
-
-/** This function returns true iff your call actually stopped the periodic
- *  work.
- *
- *  -- PAY ATTENTION... this is important --
- *
- *  NO NO #1
- *
- *     Do NOT call this function from some function that is running on the
- *     same workqueue as the work you are trying to stop might be running
- *     on!  If you violate this rule, visor_periodic_work_stop() MIGHT work,
- *     but it also MIGHT get hung up in an infinite loop saying
- *     "waiting for delayed work...".  This will happen if the delayed work
- *     you are trying to cancel has been put in the workqueue list, but can't
- *     run yet because we are running that same workqueue thread right now.
- *
- *     Bottom line: If you need to call visor_periodic_work_stop() from a
- *     workitem, be sure the workitem is on a DIFFERENT workqueue than the
- *     workitem that you are trying to cancel.
- *
- *     If I could figure out some way to check for this "no no" condition in
- *     the code, I would.  It would have saved me the trouble of writing this
- *     long comment.  And also, don't think this is some "theoretical" race
- *     condition.  It is REAL, as I have spent the day chasing it.
- *
- *  NO NO #2
- *
- *     Take close note of the locks that you own when you call this function.
- *     You must NOT own any locks that are needed by the periodic work
- *     function that is currently installed.  If you DO, a deadlock may result,
- *     because stopping the periodic work often involves waiting for the last
- *     iteration of the periodic work function to complete.  Again, if you hit
- *     this deadlock, you will get hung up in an infinite loop saying
- *     "waiting for delayed work...".
- */
-bool visor_periodic_work_stop(struct periodic_work *pw)
-{
-	bool stopped_something = false;
-
-	write_lock(&pw->lock);
-	stopped_something = pw->is_scheduled && (!pw->want_to_stop);
-	while (pw->is_scheduled) {
-		pw->want_to_stop = true;
-		if (cancel_delayed_work(&pw->work)) {
-			/* We get here if the delayed work was pending as
-			 * delayed work, but was NOT run.
-			 */
-			WARN_ON(!pw->is_scheduled);
-			pw->is_scheduled = false;
-		} else {
-			/* If we get here, either the delayed work:
-			 * - was run, OR,
-			 * - is running RIGHT NOW on another processor, OR,
-			 * - wasn't even scheduled (there is a miniscule
-			 *   timing window where this could be the case)
-			 * flush_workqueue() would make sure it is finished
-			 * executing, but that still isn't very useful, which
-			 * explains the loop...
-			 */
-		}
-		if (pw->is_scheduled) {
-			write_unlock(&pw->lock);
-			schedule_timeout_interruptible(msecs_to_jiffies(10));
-			write_lock(&pw->lock);
-		} else {
-			pw->want_to_stop = false;
-		}
-	}
-	write_unlock(&pw->lock);
-	return stopped_something;
-}
-EXPORT_SYMBOL_GPL(visor_periodic_work_stop);

drivers/staging/unisys/visorbus/visorchipset.c

@@ -29,7 +29,6 @@
 #include "controlvmchannel.h"
 #include "controlvmcompletionstatus.h"
 #include "guestlinuxdebug.h"
-#include "periodic_work.h"
 #include "version.h"
 #include "visorbus.h"
 #include "visorbus_private.h"