Revert "Xtensa SMP: Avoid a nasty situation in SMP by assuring that up_release_pending() is not re-entered."

This reverts commit 733a57b4df.

arch/xtensa/src/common/xtensa_cpupause.c

@@ -229,9 +229,6 @@ int up_cpu_pause(int cpu)
    * handler from returning until up_cpu_resume() is called; g_cpu_paused
    * is a handshake that will prefent this function from returning until
    * the CPU is actually paused.
-   *
-   * REVISIT: OR should there be logic to just skip this if the other CPU
-   * is already paused.
    */
 
   DEBUGASSERT(!spin_islocked(&g_cpu_wait[cpu]) &&
@@ -300,9 +297,6 @@ int up_cpu_resume(int cpu)
   /* Release the spinlock.  Releasing the spinlock will cause the SGI2
    * handler on 'cpu' to continue and return from interrupt to the newly
    * established thread.
-   *
-   * REVISIT: Should there be a more positive handshake to assure that the
-   * resumption is complete before returning.
    */
 
   DEBUGASSERT(spin_islocked(&g_cpu_wait[cpu]) &&

arch/xtensa/src/common/xtensa_releasepending.c

@@ -39,7 +39,6 @@
 
 #include <nuttx/config.h>
 
-#include <stdbool.h>
 #include <sched.h>
 #include <debug.h>
 
@@ -69,112 +68,92 @@
 void up_release_pending(void)
 {
   struct tcb_s *rtcb = this_task();
-#ifdef CONFIG_SMP
-  static bool busy = false;
-#endif
 
   sinfo("From TCB=%p\n", rtcb);
 
-  /* In SMP configurations, this function will be called as part of leaving
+  /* Merge the g_pendingtasks list into the ready-to-run task list */
-   * the critical section.  In that case, it may be re-entered as part of
-   * the sched_addreadytorun() processing.  We have to guard against that
-   * case.
-   */
 
-#ifdef CONFIG_SMP
+  /* sched_lock(); */
-  if (!busy)
+  if (sched_mergepending())
     {
-      busy = true;
+      /* The currently active task has changed!  We will need to
-#endif
+       * switch contexts.
+       */
 
-      /* Merge the g_pendingtasks list into the ready-to-run task list */
+      /* Update scheduler parameters */
 
-      /* sched_lock(); */
+      sched_suspend_scheduler(rtcb);
-      if (sched_mergepending())
+
+      /* Are we operating in interrupt context? */
+
+      if (CURRENT_REGS)
         {
-          /* The currently active task has changed!  We will need to
+          /* Yes, then we have to do things differently.
-           * switch contexts.
+           * Just copy the CURRENT_REGS into the OLD rtcb.
            */
 
+           xtensa_savestate(rtcb->xcp.regs);
+
+          /* Restore the exception context of the rtcb at the (new) head
+           * of the ready-to-run task list.
+           */
+
+          rtcb = this_task();
+
           /* Update scheduler parameters */
 
-          sched_suspend_scheduler(rtcb);
+          sched_resume_scheduler(rtcb);
 
-          /* Are we operating in interrupt context? */
+          /* Then switch contexts.  Any necessary address environment
-
+           * changes will be made when the interrupt returns.
-          if (CURRENT_REGS)
-            {
-              /* Yes, then we have to do things differently.
-               * Just copy the CURRENT_REGS into the OLD rtcb.
-               */
-
-               xtensa_savestate(rtcb->xcp.regs);
-
-              /* Restore the exception context of the rtcb at the (new) head
-               * of the ready-to-run task list.
-               */
-
-              rtcb = this_task();
-
-              /* Update scheduler parameters */
-
-              sched_resume_scheduler(rtcb);
-
-              /* Then switch contexts.  Any necessary address environment
-               * changes will be made when the interrupt returns.
-               */
-
-              xtensa_restorestate(rtcb->xcp.regs);
-            }
-
-          /* Copy the exception context into the TCB of the task that
-           * was currently active. if up_saveusercontext returns a non-zero
-           * value, then this is really the previously running task
-           * restarting!
            */
 
-          else if (!xtensa_context_save(rtcb->xcp.regs))
+          xtensa_restorestate(rtcb->xcp.regs);
-            {
+        }
-#if XCHAL_CP_NUM > 0
-              /* Save the co-processor state in in the suspended thread's co-
-               * processor save area.
-               */
 
-              xtensa_coproc_savestate(&rtcb->xcp.cpstate);
+      /* Copy the exception context into the TCB of the task that
+       * was currently active. if up_saveusercontext returns a non-zero
+       * value, then this is really the previously running task
+       * restarting!
+       */
+
+      else if (!xtensa_context_save(rtcb->xcp.regs))
+        {
+#if XCHAL_CP_NUM > 0
+          /* Save the co-processor state in in the suspended thread's co-
+           * processor save area.
+           */
+
+          xtensa_coproc_savestate(&rtcb->xcp.cpstate);
 #endif
-              /* Restore the exception context of the rtcb at the (new) head
+          /* Restore the exception context of the rtcb at the (new) head
-               * of the ready-to-run task list.
+           * of the ready-to-run task list.
-               */
+           */
 
-              rtcb = this_task();
+          rtcb = this_task();
 
 #if XCHAL_CP_NUM > 0
-              /* Set up the co-processor state for the newly started thread. */
+          /* Set up the co-processor state for the newly started thread. */
 
-              xtensa_coproc_restorestate(&rtcb->xcp.cpstate);
+          xtensa_coproc_restorestate(&rtcb->xcp.cpstate);
 #endif
 
 #ifdef CONFIG_ARCH_ADDRENV
-              /* Make sure that the address environment for the previously
+          /* Make sure that the address environment for the previously
-               * running task is closed down gracefully (data caches dump,
+           * running task is closed down gracefully (data caches dump,
-               * MMU flushed) and set up the address environment for the new
+           * MMU flushed) and set up the address environment for the new
-               * thread at the head of the ready-to-run list.
+           * thread at the head of the ready-to-run list.
-               */
+           */
 
-              (void)group_addrenv(rtcb);
+          (void)group_addrenv(rtcb);
 #endif
-              /* Update scheduler parameters */
+          /* Update scheduler parameters */
 
-              sched_resume_scheduler(rtcb);
+          sched_resume_scheduler(rtcb);
 
-              /* Then switch contexts */
+          /* Then switch contexts */
 
-              xtensa_context_restore(rtcb->xcp.regs);
+          xtensa_context_restore(rtcb->xcp.regs);
-            }
         }
-
-#ifdef CONFIG_SMP
-      busy = false;
     }
-#endif
 }