From 9ebab64952237f7b9b263d6dc0cdf31e83a2d5e7 Mon Sep 17 00:00:00 2001 From: Tim Sell Date: Fri, 10 Jun 2016 21:48:08 -0400 Subject: [PATCH] staging: unisys: visorbus: use kernel timer instead of workqueue A kernel timer is now used as the vehicle to periodically call the channel_interrupt function of registered visor drivers, instead of a workqueue. This simplifies a lot of things by making periodic_work.c and periodic_work.h no longer necessary. This change also means that the channel_interrupt() callbacks registered by visor drivers (via visorbus_register_visor_driver()) will now be called in atomic context (i.e., canNOT sleep) rather than kernel thread context (CAN sleep). Fortunately this did NOT necessitate any change to the existing channel_interrupt() callbacks, because none of them ever perform any operations that would be invalid in atomic context. Signed-off-by: Tim Sell Signed-off-by: David Kershner Acked-By: Neil Horman Reviewed-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman --- drivers/staging/unisys/include/visorbus.h | 10 +++-- drivers/staging/unisys/visorbus/visorbus_main.c | 54 +++++++------------------ 2 files changed, 21 insertions(+), 43 deletions(-) diff --git a/drivers/staging/unisys/include/visorbus.h b/drivers/staging/unisys/include/visorbus.h index 9baf1ec..9bb88bb 100644 --- a/drivers/staging/unisys/include/visorbus.h +++ b/drivers/staging/unisys/include/visorbus.h @@ -34,8 +34,9 @@ #include #include #include +#include +#include -#include "periodic_work.h" #include "channel.h" struct visor_driver; @@ -126,8 +127,8 @@ struct visor_driver { * device: Device struct meant for use by the bus driver * only. * list_all: Used by the bus driver to enumerate devices. - * periodic_work: Device work queue. Private use by bus driver - * only. + * timer: Timer fired periodically to do interrupt-type + * activity. * being_removed: Indicates that the device is being removed from * the bus. Private bus driver use only. * visordriver_callback_lock: Used by the bus driver to lock when handling @@ -157,7 +158,8 @@ struct visor_device { /* These fields are for private use by the bus driver only. */ struct device device; struct list_head list_all; - struct periodic_work *periodic_work; + struct timer_list timer; + bool timer_active; bool being_removed; struct semaphore visordriver_callback_lock; bool pausing; diff --git a/drivers/staging/unisys/visorbus/visorbus_main.c b/drivers/staging/unisys/visorbus/visorbus_main.c index ebdd5de..e98e720 100644 --- a/drivers/staging/unisys/visorbus/visorbus_main.c +++ b/drivers/staging/unisys/visorbus/visorbus_main.c @@ -19,7 +19,6 @@ #include "visorbus.h" #include "visorbus_private.h" #include "version.h" -#include "periodic_work.h" #include "vbuschannel.h" #include "guestlinuxdebug.h" #include "vmcallinterface.h" @@ -116,7 +115,6 @@ struct bus_type visorbus_type = { .bus_groups = visorbus_bus_groups, }; -static struct workqueue_struct *periodic_dev_workqueue; static long long bus_count; /** number of bus instances */ /** ever-increasing */ @@ -222,10 +220,6 @@ visorbus_release_device(struct device *xdev) { struct visor_device *dev = to_visor_device(xdev); - if (dev->periodic_work) { - visor_periodic_work_destroy(dev->periodic_work); - dev->periodic_work = NULL; - } if (dev->visorchannel) { visorchannel_destroy(dev->visorchannel); dev->visorchannel = NULL; @@ -530,35 +524,36 @@ unregister_driver_attributes(struct visor_driver *drv) } static void -dev_periodic_work(void *xdev) +dev_periodic_work(unsigned long __opaque) { - struct visor_device *dev = xdev; + struct visor_device *dev = (struct visor_device *)__opaque; struct visor_driver *drv = to_visor_driver(dev->device.driver); - down(&dev->visordriver_callback_lock); if (drv->channel_interrupt) drv->channel_interrupt(dev); - up(&dev->visordriver_callback_lock); - if (!visor_periodic_work_nextperiod(dev->periodic_work)) - put_device(&dev->device); + mod_timer(&dev->timer, jiffies + POLLJIFFIES_NORMALCHANNEL); } static void dev_start_periodic_work(struct visor_device *dev) { - if (dev->being_removed) + if (dev->being_removed || dev->timer_active) return; /* now up by at least 2 */ get_device(&dev->device); - if (!visor_periodic_work_start(dev->periodic_work)) - put_device(&dev->device); + dev->timer.expires = jiffies + POLLJIFFIES_NORMALCHANNEL; + add_timer(&dev->timer); + dev->timer_active = true; } static void dev_stop_periodic_work(struct visor_device *dev) { - if (visor_periodic_work_stop(dev->periodic_work)) - put_device(&dev->device); + if (!dev->timer_active) + return; + del_timer_sync(&dev->timer); + dev->timer_active = false; + put_device(&dev->device); } /** This is called automatically upon adding a visor_device (device_add), or @@ -776,17 +771,9 @@ create_visor_device(struct visor_device *dev) dev->device.release = visorbus_release_device; /* keep a reference just for us (now 2) */ get_device(&dev->device); - dev->periodic_work = - visor_periodic_work_create(POLLJIFFIES_NORMALCHANNEL, - periodic_dev_workqueue, - dev_periodic_work, - dev, dev_name(&dev->device)); - if (!dev->periodic_work) { - POSTCODE_LINUX_3(DEVICE_CREATE_FAILURE_PC, chipset_dev_no, - DIAG_SEVERITY_ERR); - err = -EINVAL; - goto err_put; - } + init_timer(&dev->timer); + dev->timer.data = (unsigned long)(dev); + dev->timer.function = dev_periodic_work; /* bus_id must be a unique name with respect to this bus TYPE * (NOT bus instance). That's why we need to include the bus @@ -1268,13 +1255,6 @@ visorbus_init(void) goto error; } - periodic_dev_workqueue = create_singlethread_workqueue("visorbus_dev"); - if (!periodic_dev_workqueue) { - POSTCODE_LINUX_2(CREATE_WORKQUEUE_PC, DIAG_SEVERITY_ERR); - err = -ENOMEM; - goto error; - } - /* This enables us to receive notifications when devices appear for * which this service partition is to be a server for. */ @@ -1297,10 +1277,6 @@ visorbus_exit(void) visorchipset_register_busdev(NULL, NULL, NULL); remove_all_visor_devices(); - flush_workqueue(periodic_dev_workqueue); /* better not be any work! */ - destroy_workqueue(periodic_dev_workqueue); - periodic_dev_workqueue = NULL; - list_for_each_safe(listentry, listtmp, &list_all_bus_instances) { struct visor_device *dev = list_entry(listentry, struct visor_device, -- 2.7.4