[ovs-dev] [PATCH 2/3] datapath: Fix OVS compat workqueue support.
Pravin B Shelar
pshelar at nicira.com
Thu Dec 22 04:28:25 UTC 2011
Resending this patch as net-namespace patches depends on it.
--8<--------------------------cut here-------------------------->8-
Signed-off-by: Pravin B Shelar <pshelar at nicira.com>
---
datapath/datapath.c | 9 +-
datapath/linux/Modules.mk | 3 +-
datapath/linux/compat/include/linux/workqueue.h | 74 ++++++---
datapath/linux/compat/workqueue.c | 213 +++++++++++++++++++++++
4 files changed, 276 insertions(+), 23 deletions(-)
create mode 100644 datapath/linux/compat/workqueue.c
diff --git a/datapath/datapath.c b/datapath/datapath.c
index 025d932..72cf9f6 100644
--- a/datapath/datapath.c
+++ b/datapath/datapath.c
@@ -2053,10 +2053,14 @@ static int __init dp_init(void)
if (err)
goto error;
- err = ovs_tnl_init();
+ err = ovs_workqueues_init();
if (err)
goto error_genl_exec;
+ err = ovs_tnl_init();
+ if (err)
+ goto error_wq;
+
err = ovs_flow_init();
if (err)
goto error_tnl_exit;
@@ -2083,6 +2087,8 @@ error_flow_exit:
ovs_flow_exit();
error_tnl_exit:
ovs_tnl_exit();
+error_wq:
+ ovs_workqueues_exit();
error_genl_exec:
genl_exec_exit();
error:
@@ -2097,6 +2103,7 @@ static void dp_cleanup(void)
ovs_vport_exit();
ovs_flow_exit();
ovs_tnl_exit();
+ ovs_workqueues_exit();
genl_exec_exit();
}
diff --git a/datapath/linux/Modules.mk b/datapath/linux/Modules.mk
index f6cb88e..40c3927 100644
--- a/datapath/linux/Modules.mk
+++ b/datapath/linux/Modules.mk
@@ -9,7 +9,8 @@ openvswitch_sources += \
linux/compat/netdevice.c \
linux/compat/reciprocal_div.c \
linux/compat/skbuff-openvswitch.c \
- linux/compat/time.c
+ linux/compat/time.c \
+ linux/compat/workqueue.c
openvswitch_headers += \
linux/compat/include/linux/compiler.h \
linux/compat/include/linux/compiler-gcc.h \
diff --git a/datapath/linux/compat/include/linux/workqueue.h b/datapath/linux/compat/include/linux/workqueue.h
index 01c6345..919afe3 100644
--- a/datapath/linux/compat/include/linux/workqueue.h
+++ b/datapath/linux/compat/include/linux/workqueue.h
@@ -1,41 +1,73 @@
#ifndef __LINUX_WORKQUEUE_WRAPPER_H
#define __LINUX_WORKQUEUE_WRAPPER_H 1
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,23)
#include_next <linux/workqueue.h>
+static inline int __init ovs_workqueues_init(void) { return 0; }
+static inline void ovs_workqueues_exit(void) {}
+
+#else
+#include <linux/timer.h>
+
+int __init ovs_workqueues_init(void);
+void ovs_workqueues_exit(void);
-#include <linux/version.h>
-#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,23)
/* Older kernels have an implementation of work queues with some very bad
* characteristics when trying to cancel work (potential deadlocks, use after
- * free, etc. Here we directly use timers instead for delayed work. It's not
- * optimal but it is better than the alternative. Note that work queues
- * normally run in process context but this will cause them to operate in
- * softirq context.
+ * free, etc. Therefore we implement simple ovs specific work queue using
+ * single worker thread. work-queue API are kept similar for compatibility.
*/
+struct work_struct;
-#include <linux/timer.h>
+typedef void (*work_func_t)(struct work_struct *work);
-#undef DECLARE_DELAYED_WORK
-#define DECLARE_DELAYED_WORK(n, f) \
- struct timer_list n = TIMER_INITIALIZER((void (*)(unsigned long))f, 0, 0)
+#define work_data_bits(work) ((unsigned long *)(&(work)->data))
-#define schedule_delayed_work rpl_schedule_delayed_work
-static inline int schedule_delayed_work(struct timer_list *timer, unsigned long delay)
-{
- if (timer_pending(timer))
- return 0;
+struct work_struct {
+#define WORK_STRUCT_PENDING 0 /* T if work item pending execution */
+ atomic_long_t data;
+ struct list_head entry;
+ work_func_t func;
+};
+
+#define WORK_DATA_INIT() ATOMIC_LONG_INIT(0)
+
+#define work_clear_pending(work) \
+ clear_bit(WORK_STRUCT_PENDING, work_data_bits(work))
+
+struct delayed_work {
+ struct work_struct work;
+ struct timer_list timer;
+};
- mod_timer(timer, jiffies + delay);
- return 1;
+#define __WORK_INITIALIZER(n, f) { \
+ .data = WORK_DATA_INIT(), \
+ .entry = { &(n).entry, &(n).entry }, \
+ .func = (f), \
}
-#define cancel_delayed_work_sync rpl_cancel_delayed_work_sync
-static inline int cancel_delayed_work_sync(struct timer_list *timer)
-{
- return del_timer_sync(timer);
+#define __DELAYED_WORK_INITIALIZER(n, f) { \
+ .work = __WORK_INITIALIZER((n).work, (f)), \
+ .timer = TIMER_INITIALIZER(NULL, 0, 0), \
}
+#define DECLARE_DELAYED_WORK(n, f) \
+ struct delayed_work n = __DELAYED_WORK_INITIALIZER(n, f)
+
+#define schedule_delayed_work rpl_schedule_delayed_work
+int schedule_delayed_work(struct delayed_work *dwork, unsigned long delay);
+
+#define cancel_delayed_work_sync rpl_cancel_delayed_work_sync
+int cancel_delayed_work_sync(struct delayed_work *dwork);
+
+#define INIT_WORK(_work, _func) \
+ do { \
+ (_work)->data = (atomic_long_t) WORK_DATA_INIT(); \
+ INIT_LIST_HEAD(&(_work)->entry); \
+ (_work)->func = (_func); \
+ } while (0)
+
#endif /* kernel version < 2.6.23 */
#endif
diff --git a/datapath/linux/compat/workqueue.c b/datapath/linux/compat/workqueue.c
new file mode 100644
index 0000000..883665b
--- /dev/null
+++ b/datapath/linux/compat/workqueue.c
@@ -0,0 +1,213 @@
+/*
+ * Derived from the kernel/workqueue.c
+ *
+ * This is the generic async execution mechanism. Work items as are
+ * executed in process context.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/init.h>
+#include <linux/signal.h>
+#include <linux/completion.h>
+#include <linux/workqueue.h>
+#include <linux/slab.h>
+#include <linux/cpu.h>
+#include <linux/notifier.h>
+#include <linux/kthread.h>
+#include <linux/hardirq.h>
+#include <linux/mempolicy.h>
+#include <linux/kallsyms.h>
+#include <linux/debug_locks.h>
+#include <linux/lockdep.h>
+#include <linux/idr.h>
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,23)
+
+static spinlock_t wq_lock;
+static struct list_head workq;
+static wait_queue_head_t more_work;
+static struct task_struct *workq_thread;
+static struct work_struct *current_work;
+
+static void queue_work(struct work_struct *work)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&wq_lock, flags);
+ list_add_tail(&work->entry, &workq);
+ wake_up(&more_work);
+ spin_unlock_irqrestore(&wq_lock, flags);
+}
+
+static void _delayed_work_timer_fn(unsigned long __data)
+{
+ struct delayed_work *dwork = (struct delayed_work *)__data;
+ queue_work(&dwork->work);
+}
+
+static void __queue_delayed_work(struct delayed_work *dwork,
+ unsigned long delay)
+{
+ struct timer_list *timer = &dwork->timer;
+ struct work_struct *work = &dwork->work;
+
+ BUG_ON(timer_pending(timer));
+ BUG_ON(!list_empty(&work->entry));
+
+ timer->expires = jiffies + delay;
+ timer->data = (unsigned long)dwork;
+ timer->function = _delayed_work_timer_fn;
+
+ add_timer(timer);
+}
+
+int schedule_delayed_work(struct delayed_work *dwork, unsigned long delay)
+{
+ if (test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(&dwork->work)))
+ return 0;
+
+ if (delay == 0)
+ queue_work(&dwork->work);
+ else
+ __queue_delayed_work(dwork, delay);
+
+ return 1;
+}
+
+struct wq_barrier {
+ struct work_struct work;
+ struct completion done;
+};
+
+static void wq_barrier_func(struct work_struct *work)
+{
+ struct wq_barrier *barr = container_of(work, struct wq_barrier, work);
+ complete(&barr->done);
+}
+
+static void workqueue_barrier(struct work_struct *work)
+{
+ bool need_barrier;
+ struct wq_barrier barr;
+
+ spin_lock_irq(&wq_lock);
+ if (current_work != work)
+ need_barrier = false;
+ else {
+ INIT_WORK(&barr.work, wq_barrier_func);
+ init_completion(&barr.done);
+ list_add(&barr.work.entry, &workq);
+ wake_up(&more_work);
+ need_barrier = true;
+ }
+ spin_unlock_irq(&wq_lock);
+
+ if (need_barrier)
+ wait_for_completion(&barr.done);
+}
+
+static int try_to_grab_pending(struct work_struct *work)
+{
+ int ret;
+
+ BUG_ON(in_interrupt());
+
+ if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work)))
+ return 0;
+
+ spin_lock_irq(&wq_lock);
+ if (!list_empty(&work->entry)) {
+ list_del_init(&work->entry);
+ ret = 0;
+ } else
+ /* Already executed, retry. */
+ ret = -1;
+ spin_unlock_irq(&wq_lock);
+
+ return ret;
+}
+
+static int __cancel_work_timer(struct work_struct *work,
+ struct timer_list *timer)
+{
+ int ret;
+
+ for (;;) {
+ ret = (timer && likely(del_timer(timer)));
+ if (ret) /* Was active timer, return true. */
+ break;
+
+ /* Inactive timer case */
+ ret = try_to_grab_pending(work);
+ if (!ret)
+ break;
+ }
+ workqueue_barrier(work);
+ work_clear_pending(work);
+ return ret;
+}
+
+int cancel_delayed_work_sync(struct delayed_work *dwork)
+{
+ return __cancel_work_timer(&dwork->work, &dwork->timer);
+}
+
+static void run_workqueue(void)
+{
+ spin_lock_irq(&wq_lock);
+ while (!list_empty(&workq)) {
+ struct work_struct *work = list_entry(workq.next,
+ struct work_struct, entry);
+
+ work_func_t f = work->func;
+ list_del_init(workq.next);
+ current_work = work;
+ spin_unlock_irq(&wq_lock);
+
+ work_clear_pending(work);
+ f(work);
+
+ BUG_ON(in_interrupt());
+ spin_lock_irq(&wq_lock);
+ current_work = NULL;
+ }
+ spin_unlock_irq(&wq_lock);
+}
+
+static int worker_thread(void *dummy)
+{
+ for (;;) {
+ wait_event_interruptible(more_work,
+ (kthread_should_stop() || !list_empty(&workq)));
+
+ if (kthread_should_stop())
+ break;
+
+ run_workqueue();
+ }
+
+ return 0;
+}
+
+int __init ovs_workqueues_init(void)
+{
+ spin_lock_init(&wq_lock);
+ INIT_LIST_HEAD(&workq);
+ init_waitqueue_head(&more_work);
+
+ workq_thread = kthread_create(worker_thread, NULL, "ovs_workq");
+ if (IS_ERR(workq_thread))
+ return PTR_ERR(workq_thread);
+
+ wake_up_process(workq_thread);
+ return 0;
+}
+
+void ovs_workqueues_exit(void)
+{
+ BUG_ON(!list_empty(&workq));
+ kthread_stop(workq_thread);
+}
+#endif
--
1.7.1
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