diff options
Diffstat (limited to 'drivers/staging/unisys/visorutil/periodic_work.c')
-rw-r--r-- | drivers/staging/unisys/visorutil/periodic_work.c | 204 |
1 files changed, 0 insertions, 204 deletions
diff --git a/drivers/staging/unisys/visorutil/periodic_work.c b/drivers/staging/unisys/visorutil/periodic_work.c deleted file mode 100644 index abbfb4889..000000000 --- a/drivers/staging/unisys/visorutil/periodic_work.c +++ /dev/null @@ -1,204 +0,0 @@ -/* periodic_work.c - * - * 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. - */ - -/* - * Helper functions to schedule periodic work in Linux kernel mode. - */ - -#include "timskmod.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) < 0) { - 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) < 0) { - 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); - SLEEPJIFFIES(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); |