staging: unisys: visorbus: remove periodic_work.h/.c (8a64f954) · Commits · e / devices / android_kernel_teracube_2e

drivers/staging/unisys/include/periodic_work.h

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		/* 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

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		@@ -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

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		/* 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

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		@@ -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"