From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758608AbcFHVXB (ORCPT ); Wed, 8 Jun 2016 17:23:01 -0400 Received: from mail1.bemta12.messagelabs.com ([216.82.251.7]:45783 "EHLO mail1.bemta12.messagelabs.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755219AbcFHVOh (ORCPT ); Wed, 8 Jun 2016 17:14:37 -0400 X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFjrBIsWRWlGSWpSXmKPExsVywNY2Q3dnV0S 4wffZchYL25awWFzeNYfNgcnj8ya5AMYo1sy8pPyKBNaM5oV97AXPDSt2bLrG1sB4QauLkYtD SGAXo8T6ti2sEM5+Rom+9V9YIJxLjBJb7v+DyqxllNiwfi87hLOFUeLfqidsXYycHGwCBhIz7 9xlB7FFBM6zSDy9ldvFyMHBLKAmceO7JUhYWCBK4mdTMyOIzSKgInFq6R82kBJeAS+JvhNJIG EJATmJk8cms4LYnEDhh7/WMoHYQgKeEi3vHrND2GoSh88+YoOoD5b48uQomM0rIChxcuYTFhC bWUBC4uCLF8wTGIVmIUnNQpJawMi0ilGjOLWoLLVI18hEL6koMz2jJDcxM0fX0NBILze1uDgx PTUnMalYLzk/dxMjMITrGRgYdzAunO51iFGSg0lJlLfMPSJciC8pP6UyI7E4I76oNCe1+BCjD AeHkgRvcidQTrAoNT21Ii0zBxhNMGkJDh4lEd6TIGne4oLE3OLMdIjUKUZFKXFeO5CEAEgioz QPrg0WwZcYZaWEeRkZGBiEeApSi3IzS1DlXzGKczAqCfNagEzhycwrgZv+CmgxE9Di5UfCQRa XJCKkpBoYLfMqD1g/4Xlc9Mb0x9enYdtyTZ+1LOlb4PFc/9700iVdlzjuiUiuXXLPeaLf9Tvn gp+GbJgQ++/VXa8Vd+Ymsz1cZaB5r2fdSjPp31W8Cy6fnB6hx5PBl6Ao4P2JodXjyqVtGzqb5 y49HpUW9O975rP7zT8aZ3quZLeONu83yJto57bEguGrmxJLcUaioRZzUXEiAKfKxo7bAgAA X-Env-Sender: David.Kershner@unisys.com X-Msg-Ref: server-12.tower-200.messagelabs.com!1465420468!5672196!11 X-Originating-IP: [192.61.61.104] X-StarScan-Received: X-StarScan-Version: 8.46; banners=-,-,- X-VirusChecked: Checked From: David Kershner To: , , , , , , , , , , , , , , , , , , , , , CC: Tim Sell Subject: [PATCH v4 10/29] staging: unisys: visorbus: use kernel timer instead of workqueue Date: Wed, 8 Jun 2016 17:14:04 -0400 Message-ID: <1465420463-24982-11-git-send-email-david.kershner@unisys.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1465420463-24982-1-git-send-email-david.kershner@unisys.com> References: <1465420463-24982-1-git-send-email-david.kershner@unisys.com> X-OriginalArrivalTime: 08 Jun 2016 21:14:28.0350 (UTC) FILETIME=[BDDEB9E0:01D1C1CA] MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Tim Sell 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 --- 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, -- 1.9.1 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: David Kershner Subject: [PATCH v4 10/29] staging: unisys: visorbus: use kernel timer instead of workqueue Date: Wed, 8 Jun 2016 17:14:04 -0400 Message-ID: <1465420463-24982-11-git-send-email-david.kershner@unisys.com> In-Reply-To: <1465420463-24982-1-git-send-email-david.kershner@unisys.com> References: <1465420463-24982-1-git-send-email-david.kershner@unisys.com> MIME-Version: 1.0 Content-Type: text/plain List-ID: To: corbet@lwn.net, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, david.kershner@unisys.com, gregkh@linuxfoundation.org, erik.arfvidson@unisys.com, timothy.sell@unisys.com, hofrat@osadl.org, dzickus@redhat.com, jes.sorensen@redhat.com, alexander.curtin@unisys.com, janani.rvchndrn@gmail.com, sudipm.mukherjee@gmail.com, prarit@redhat.com, david.binder@unisys.com, nhorman@redhat.com, dan.j.williams@intel.com, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, driverdev-devel@linuxdriverproject.org, sparmaintainer@unisys.com Cc: Tim Sell From: Tim Sell 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 --- 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, -- 1.9.1