wireless/bluetooth: Soften use of enter_critical_sectino() which is a performance hog in SMP configurations. Replace with spin_lock_irqsave() in most cases. That is the same for single core CPUs, but much more efficient in SMP configurations. And better, repace with sched_lock() if there is really no necessity to disable interrupts too.

wireless/bluetooth/bt_buf.c

@@ -242,7 +242,7 @@ FAR struct bt_buf_s *bt_buf_alloc(enum bt_buf_type_e type,
    * then try the list of messages reserved for interrupt handlers
    */
 
-  flags = enter_critical_section(); /* Always necessary in SMP mode */
+  flags = spin_lock_irqsave(); /* Always necessary in SMP mode */
   if (up_interrupt_context())
     {
 #if CONFIG_BLUETOOTH_BUFFER_PREALLOC > CONFIG_BLUETOOTH_BUFFER_IRQRESERVE
@@ -253,7 +253,7 @@ FAR struct bt_buf_s *bt_buf_alloc(enum bt_buf_type_e type,
           buf            = g_buf_free;
           g_buf_free     = buf->flink;
 
-          leave_critical_section(flags);
+          spin_unlock_irqrestore(flags);
           pool           = POOL_BUFFER_GENERAL;
         }
       else
@@ -266,13 +266,13 @@ FAR struct bt_buf_s *bt_buf_alloc(enum bt_buf_type_e type,
           buf            = g_buf_free_irq;
           g_buf_free_irq = buf->flink;
 
-          leave_critical_section(flags);
+          spin_unlock_irqrestore(flags);
           pool           = POOL_BUFFER_IRQ;
         }
       else
 #endif
         {
-          leave_critical_section(flags);
+          spin_unlock_irqrestore(flags);
           return NULL;
         }
     }
@@ -422,10 +422,10 @@ void bt_buf_release(FAR struct bt_buf_s *buf)
        * list from interrupt handlers.
        */
 
-      flags      = enter_critical_section();
+      flags      = spin_lock_irqsave();
       buf->flink = g_buf_free;
       g_buf_free = buf;
-      leave_critical_section(flags);
+      spin_unlock_irqrestore(flags);
     }
   else
 #endif
@@ -441,10 +441,10 @@ void bt_buf_release(FAR struct bt_buf_s *buf)
        * list from interrupt handlers.
        */
 
-      flags          = enter_critical_section();
+      flags          = spin_lock_irqsave();
       buf->flink     = g_buf_free_irq;
       g_buf_free_irq = buf;
-      leave_critical_section(flags);
+      spin_unlock_irqrestore(flags);
     }
   else
 #endif

wireless/bluetooth/bt_hcicore.c

@@ -50,10 +50,10 @@
 #include <stdio.h>
 #include <fcntl.h>
 #include <time.h>
+#include <sched.h>
 #include <errno.h>
 #include <debug.h>
 
-#include <nuttx/irq.h>
 #include <nuttx/clock.h>
 #include <nuttx/kthread.h>
 #include <nuttx/semaphore.h>
@@ -1518,20 +1518,23 @@ int bt_hci_cmd_send_sync(uint16_t opcode, FAR struct bt_buf_s *buf,
   else
     {
       struct timespec abstime;
-      irqstate_t flags;
 
       /* Wait for the response to the command.  An I/O error will be
        * declared if the response does not occur within the timeout
        * interval.
        *
-       * Get the current time.  Not that we must be in critical section here
-       * so that we can be assured that there will be no context switches
+       * REVISIT: The cause of the timeout could be a failure to receive a
+       * response to a sent frame or, perhaps, a failure to send the frame.
+       * Should there also be logic to flush any unsent Tx packets?
+       *
+       * Get the current time.  Not that we lock the scheduler here so that
+       * we can be assured that there will be no context switches will occur
        * between the time that we calculate the delay time and until we get
        * to the wait.
        */
 
-      flags = enter_critical_section();
-      ret   = clock_gettime(CLOCK_REALTIME, &abstime);
+      sched_lock();
+      ret = clock_gettime(CLOCK_REALTIME, &abstime);
       if (ret >= 0)
         {
           /* Add the offset to the time in the future */
@@ -1560,7 +1563,7 @@ int bt_hci_cmd_send_sync(uint16_t opcode, FAR struct bt_buf_s *buf,
           while (ret == -EINTR);
         }
 
-      leave_critical_section(flags);
+      sched_unlock();
     }
 
   /* Indicate failure if we failed to get the response */

wireless/bluetooth/bt_netdev.c

@@ -662,7 +662,7 @@ static int btnet_ifdown(FAR struct net_driver_s *netdev)
 
   /* Disable interruption */
 
-  flags = enter_critical_section();
+  flags = spin_lock_irqsave();
 
   /* Cancel the TX poll timer and TX timeout timers */
 
@@ -676,7 +676,7 @@ static int btnet_ifdown(FAR struct net_driver_s *netdev)
   /* Mark the device "down" */
 
   priv->bd_bifup = false;
-  leave_critical_section(flags);
+  spin_unlock_irqrestore(flags);
   return OK;
 }