sched: remove csection in event

We hope to replace the large lock with a small lock to improve concurrency performance.

Signed-off-by: hujun5 <hujun5@xiaomi.com>

include/nuttx/event.h

@@ -31,6 +31,7 @@
 
 #include <nuttx/list.h>
 #include <nuttx/semaphore.h>
+#include <nuttx/spinlock.h>
 
 /****************************************************************************
  * Pre-processor Definitions
@@ -70,8 +71,9 @@ struct nxevent_wait_s
 
 struct nxevent_s
 {
-  struct list_node         list;    /* Waiting list of nxevent_wait_t */
+  struct list_node         list;   /* Waiting list of nxevent_wait_t */
-  volatile nxevent_mask_t  events;  /* Pending Events */
+  volatile nxevent_mask_t  events; /* Pending Events */
+  spinlock_t               lock;   /* Spinlock */
 };
 
 #ifdef CONFIG_FS_NAMED_EVENTS

sched/event/event_init.c

@@ -49,5 +49,6 @@
 void nxevent_init(FAR nxevent_t *event, nxevent_mask_t events)
 {
   event->events = events;
+  spin_lock_init(&event->lock);
   list_initialize(&event->list);
 }

sched/event/event_post.c

@@ -32,23 +32,6 @@
  * Private Functions
  ****************************************************************************/
 
-/****************************************************************************
- * Name: nxevent_sem_post
- ****************************************************************************/
-
-static inline_function int nxevent_sem_post(FAR sem_t *sem)
-{
-  int semcount;
-
-  nxsem_get_value(sem, &semcount);
-  if (semcount < 1)
-    {
-      return nxsem_post(sem);
-    }
-
-  return 0;
-}
-
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
@@ -98,7 +81,7 @@ int nxevent_post(FAR nxevent_t *event, nxevent_mask_t events,
       return -EINVAL;
     }
 
-  flags = enter_critical_section();
+  flags = spin_lock_irqsave_nopreempt(&event->lock);
 
   if ((eflags & NXEVENT_POST_SET) != 0)
     {
@@ -113,12 +96,6 @@ int nxevent_post(FAR nxevent_t *event, nxevent_mask_t events,
     {
       postall = ((eflags & NXEVENT_POST_ALL) != 0);
 
-      /* Hold schedule lock here to avoid context switch if post high
-       * priority task.
-       */
-
-      sched_lock();
-
       list_for_every_entry_safe(&event->list, wait, tmp,
                                 nxevent_wait_t, node)
         {
@@ -129,7 +106,7 @@ int nxevent_post(FAR nxevent_t *event, nxevent_mask_t events,
             {
               list_delete_init(&wait->node);
 
-              ret = nxevent_sem_post(&wait->sem);
+              ret = nxsem_post(&wait->sem);
               if (ret < 0)
                 {
                   continue;
@@ -156,11 +133,9 @@ int nxevent_post(FAR nxevent_t *event, nxevent_mask_t events,
         {
           event->events &= ~clear;
         }
-
-      sched_unlock();
     }
 
-  leave_critical_section(flags);
+  spin_unlock_irqrestore_nopreempt(&event->lock, flags);
 
   return ret;
 }

sched/event/event_wait.c

@@ -80,7 +80,7 @@ nxevent_mask_t nxevent_tickwait_wait(FAR nxevent_t *event,
       events = ~0;
     }
 
-  flags = enter_critical_section();
+  flags = spin_lock_irqsave(&event->lock);
 
   if ((eflags & NXEVENT_WAIT_RESET) != 0)
     {
@@ -126,6 +126,7 @@ nxevent_mask_t nxevent_tickwait_wait(FAR nxevent_t *event,
       wait->eflags = eflags;
 
       list_add_tail(&event->list, &(wait->node));
+      spin_unlock_irqrestore(&event->lock, flags);
 
       /* Wait for the event */
 
@@ -141,19 +142,25 @@ nxevent_mask_t nxevent_tickwait_wait(FAR nxevent_t *event,
       /* Destroy local variables */
 
       nxsem_destroy(&(wait->sem));
-      list_delete(&(wait->node));
 
+      flags = spin_lock_irqsave(&event->lock);
       if (ret == 0)
         {
           events = wait->expect;
+          DEBUGASSERT(!list_in_list(&(wait->node)));
         }
       else
         {
+          if (list_in_list(&(wait->node)))
+            {
+              list_delete(&(wait->node));
+            }
+
           events = 0;
         }
     }
 
-  leave_critical_section(flags);
+  spin_unlock_irqrestore(&event->lock, flags);
 
   return events;
 }