From: David Kershner <david.kershner@unisys.com> 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 <Timothy.Sell@unisys.com> Subject: [PATCH v4 10/29] staging: unisys: visorbus: use kernel timer instead of workqueue Date: Wed, 8 Jun 2016 17:14:04 -0400 [thread overview] Message-ID: <1465420463-24982-11-git-send-email-david.kershner@unisys.com> (raw) In-Reply-To: <1465420463-24982-1-git-send-email-david.kershner@unisys.com> From: Tim Sell <Timothy.Sell@unisys.com> 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 <Timothy.Sell@unisys.com> Signed-off-by: David Kershner <david.kershner@unisys.com> --- 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 <linux/poll.h> #include <linux/kernel.h> #include <linux/uuid.h> +#include <linux/seq_file.h> +#include <linux/slab.h> -#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
WARNING: multiple messages have this Message-ID (diff)
From: David Kershner <david.kershner@unisys.com> 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 <Timothy.Sell@unisys.com> Subject: [PATCH v4 10/29] staging: unisys: visorbus: use kernel timer instead of workqueue Date: Wed, 8 Jun 2016 17:14:04 -0400 [thread overview] Message-ID: <1465420463-24982-11-git-send-email-david.kershner@unisys.com> (raw) In-Reply-To: <1465420463-24982-1-git-send-email-david.kershner@unisys.com> From: Tim Sell <Timothy.Sell@unisys.com> 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 <Timothy.Sell@unisys.com> Signed-off-by: David Kershner <david.kershner@unisys.com> --- 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 <linux/poll.h> #include <linux/kernel.h> #include <linux/uuid.h> +#include <linux/seq_file.h> +#include <linux/slab.h> -#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
next prev parent reply other threads:[~2016-06-08 21:23 UTC|newest] Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-06-08 21:13 [PATCH v4 00/29] Fixed issues raised by tglx, then move visorbus to drivers/virt David Kershner 2016-06-08 21:13 ` David Kershner 2016-06-08 21:13 ` [PATCH v4 01/29] staging: unisys: visorbus: remove return values for write_vbus functions David Kershner 2016-06-08 21:13 ` David Kershner 2016-06-08 21:13 ` [PATCH v4 02/29] staging: unisys: visorbus: check parahotplug_request_complete_result David Kershner 2016-06-08 21:13 ` David Kershner 2016-06-08 21:13 ` [PATCH v4 03/29] staging: unisys: visorbus: remove unused module parameters David Kershner 2016-06-08 21:13 ` David Kershner 2016-06-08 21:13 ` [PATCH v4 04/29] staging: unisys: visorbus: remove unused struct David Kershner 2016-06-08 21:13 ` David Kershner 2016-06-08 21:13 ` [PATCH v4 05/29] staging: unisys: visorbus: modify format string to match argument David Kershner 2016-06-08 21:13 ` David Kershner 2016-06-08 21:14 ` [PATCH v4 06/29] staging: unisys: visornic: Correct comment spelling mistake David Kershner 2016-06-08 21:14 ` David Kershner 2016-06-08 21:14 ` [PATCH v4 07/29] staging: unisys: include: Remove thread-related enum members David Kershner 2016-06-08 21:14 ` David Kershner 2016-06-08 21:14 ` [PATCH v4 08/29] staging: unisys: visorbus: removed unused periodic_test_workqueue David Kershner 2016-06-08 21:14 ` David Kershner 2016-06-08 21:14 ` [PATCH v4 09/29] staging: unisys: visorinput: remove unnecessary locking David Kershner 2016-06-08 21:14 ` David Kershner 2016-06-09 9:01 ` Thomas Gleixner 2016-06-09 9:01 ` Thomas Gleixner 2016-06-09 12:03 ` Sell, Timothy C 2016-06-09 12:03 ` Sell, Timothy C 2016-06-09 19:55 ` Thomas Gleixner 2016-06-09 19:55 ` Thomas Gleixner 2016-06-09 20:30 ` Sell, Timothy C 2016-06-09 20:30 ` Sell, Timothy C 2016-06-11 3:34 ` Sell, Timothy C 2016-06-11 3:34 ` Sell, Timothy C 2016-06-08 21:14 ` David Kershner [this message] 2016-06-08 21:14 ` [PATCH v4 10/29] staging: unisys: visorbus: use kernel timer instead of workqueue David Kershner 2016-06-08 21:14 ` [PATCH v4 11/29] staging: unisys: visorbus: remove periodic_work.h/.c David Kershner 2016-06-08 21:14 ` David Kershner 2016-06-08 21:14 ` [PATCH v4 12/29] staging: unisys: visorbus: Make visordriver_callback_lock a mutex David Kershner 2016-06-08 21:14 ` David Kershner 2016-06-08 21:14 ` [PATCH v4 13/29] staging: unisys: visorbus: Remove unnecessary EXPORT_SYMBOL statements David Kershner 2016-06-08 21:14 ` David Kershner 2016-06-08 21:14 ` [PATCH v4 14/29] staging: unisys: visorbus: Remove unused functions David Kershner 2016-06-08 21:14 ` David Kershner 2016-06-08 21:14 ` [PATCH v4 15/29] staging: unisys: Remove reference to unused STANDALONE_CLIENT David Kershner 2016-06-08 21:14 ` David Kershner 2016-06-08 21:14 ` [PATCH v4 16/29] staging: unisys: visorbus: remove unused parameter from function David Kershner 2016-06-08 21:14 ` David Kershner 2016-06-08 21:14 ` [PATCH v4 17/29] staging: unisys: visorbus: fix commenting in vbusdevinfo.h David Kershner 2016-06-08 21:14 ` David Kershner 2016-06-08 21:14 ` [PATCH v4 18/29] staging: unisys: visorbus: fix commenting in visorbus_main.c David Kershner 2016-06-08 21:14 ` David Kershner 2016-06-08 21:14 ` [PATCH v4 19/29] staging: unisys: visorbus: fix visorchannel.c comments David Kershner 2016-06-08 21:14 ` David Kershner 2016-06-08 21:14 ` [PATCH v4 20/29] staging: unisys: visorbus: Rectify commenting in visorchipset.c David Kershner 2016-06-08 21:14 ` David Kershner 2016-06-08 21:14 ` [PATCH v4 21/29] staging: unisys: visorbus: Move visorbus-unique functions to private header David Kershner 2016-06-08 21:14 ` David Kershner 2016-06-08 21:14 ` [PATCH v4 22/29] staging: unisys: visorbus: rectify kerneldoc comment for struct David Kershner 2016-06-08 21:14 ` David Kershner 2016-06-08 21:14 ` [PATCH v4 23/29] staging: unisys: visorbus: Remove notifier-related code from visorbus David Kershner 2016-06-08 21:14 ` David Kershner 2016-06-08 21:14 ` [PATCH v4 24/29] staging: unisys: visorbus: Rename function to follow existing convention David Kershner 2016-06-08 21:14 ` David Kershner 2016-06-08 21:14 ` [PATCH v4 25/29] staging: unisys: visorbus: fix visorbus_private.h comments David Kershner 2016-06-08 21:14 ` David Kershner 2016-06-08 21:14 ` [PATCH v4 26/29] staging: unisys: Move vbushelper.h to visorbus directory David Kershner 2016-06-08 21:14 ` David Kershner 2016-06-08 21:14 ` [PATCH v4 27/29] include: linux: visorbus: Add visorbus to include/linux directory David Kershner 2016-06-08 21:14 ` David Kershner 2016-06-08 21:14 ` [PATCH v4 28/29] Documentation: Move visorbus documentation from staging to Documentation/ David Kershner 2016-06-08 21:14 ` David Kershner 2016-06-08 21:14 ` [PATCH v4 29/29] drivers: Add visorbus to the drivers/virt directory David Kershner 2016-06-08 21:14 ` David Kershner
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