diff --git a/sched/sched/sched_getaffinity.c b/sched/sched/sched_getaffinity.c
index b94f997eb2da0..1226e25a9195e 100644
--- a/sched/sched/sched_getaffinity.c
+++ b/sched/sched/sched_getaffinity.c
@@ -75,7 +75,6 @@ int nxsched_get_affinity(pid_t pid, size_t cpusetsize, FAR cpu_set_t *mask)
 
   /* Verify that the PID corresponds to a real task */
 
-  sched_lock();
   if (pid == 0)
     {
       tcb = this_task();
@@ -97,7 +96,6 @@ int nxsched_get_affinity(pid_t pid, size_t cpusetsize, FAR cpu_set_t *mask)
       ret = OK;
     }
 
-  sched_unlock();
   return ret;
 }
 
diff --git a/sched/sched/sched_getparam.c b/sched/sched/sched_getparam.c
index fd196be53b2ed..6fd58306b4794 100644
--- a/sched/sched/sched_getparam.c
+++ b/sched/sched/sched_getparam.c
@@ -93,7 +93,6 @@ int nxsched_get_param(pid_t pid, FAR struct sched_param *param)
     {
       /* Get the TCB associated with this PID */
 
-      sched_lock();
       tcb = nxsched_get_tcb(pid);
       if (!tcb)
         {
@@ -136,8 +135,6 @@ int nxsched_get_param(pid_t pid, FAR struct sched_param *param)
             }
 #endif
         }
-
-      sched_unlock();
     }
 
   return ret;
diff --git a/sched/sched/sched_setparam.c b/sched/sched/sched_setparam.c
index 8259d61e5e212..b8649799935a0 100644
--- a/sched/sched/sched_setparam.c
+++ b/sched/sched/sched_setparam.c
@@ -78,7 +78,6 @@ int nxsched_set_param(pid_t pid, FAR const struct sched_param *param)
 {
   FAR struct tcb_s *rtcb;
   FAR struct tcb_s *tcb;
-  int ret;
 
   /* Verify that the requested priority is in the valid range */
 
@@ -87,12 +86,6 @@ int nxsched_set_param(pid_t pid, FAR const struct sched_param *param)
       return -EINVAL;
     }
 
-  /* Prohibit modifications to the head of the ready-to-run task
-   * list while adjusting the priority
-   */
-
-  sched_lock();
-
   /* Check if the task to reprioritize is the calling task */
 
   rtcb = this_task();
@@ -110,8 +103,7 @@ int nxsched_set_param(pid_t pid, FAR const struct sched_param *param)
         {
           /* No task with this PID was found */
 
-          ret = -ESRCH;
-          goto errout_with_lock;
+          return -ESRCH;
         }
     }
 
@@ -128,8 +120,7 @@ int nxsched_set_param(pid_t pid, FAR const struct sched_param *param)
       if (param->sched_ss_max_repl < 1 ||
           param->sched_ss_max_repl > CONFIG_SCHED_SPORADIC_MAXREPL)
         {
-          ret = -EINVAL;
-          goto errout_with_lock;
+          return -EINVAL;
         }
 
       /* Convert timespec values to system clock ticks */
@@ -163,8 +154,7 @@ int nxsched_set_param(pid_t pid, FAR const struct sched_param *param)
       if (repl_ticks < budget_ticks)
 #endif
         {
-          ret = -EINVAL;
-          goto errout_with_lock;
+          return -EINVAL;
         }
 
       /* Stop/reset current sporadic scheduling */
@@ -198,18 +188,14 @@ int nxsched_set_param(pid_t pid, FAR const struct sched_param *param)
       leave_critical_section(flags);
       if (ret < 0)
         {
-          goto errout_with_lock;
+          return ret;
         }
     }
 #endif
 
   /* Then perform the reprioritization */
 
-  ret = nxsched_reprioritize(tcb, param->sched_priority);
-
-errout_with_lock:
-  sched_unlock();
-  return ret;
+  return nxsched_reprioritize(tcb, param->sched_priority);
 }
 
 /****************************************************************************
diff --git a/sched/sched/sched_setscheduler.c b/sched/sched/sched_setscheduler.c
index b20433dcca91c..4c6ed2a274183 100644
--- a/sched/sched/sched_setscheduler.c
+++ b/sched/sched/sched_setscheduler.c
@@ -80,7 +80,6 @@ int nxsched_set_scheduler(pid_t pid, int policy,
 {
   FAR struct tcb_s *tcb;
   irqstate_t flags;
-  int ret;
 
   /* Check for supported scheduling policy */
 
@@ -120,12 +119,6 @@ int nxsched_set_scheduler(pid_t pid, int policy,
       return -ESRCH;
     }
 
-  /* Prohibit any context switches while we muck with priority and scheduler
-   * settings.
-   */
-
-  sched_lock();
-
   /* Further, disable timer interrupts while we set up scheduling policy. */
 
   flags = enter_critical_section();
@@ -270,14 +263,11 @@ int nxsched_set_scheduler(pid_t pid, int policy,
 
   /* Set the new priority */
 
-  ret = nxsched_reprioritize(tcb, param->sched_priority);
-  sched_unlock();
-  return ret;
+  return nxsched_reprioritize(tcb, param->sched_priority);
 
 #ifdef CONFIG_SCHED_SPORADIC
 errout_with_irq:
   leave_critical_section(flags);
-  sched_unlock();
   return ret;
 #endif
 }
diff --git a/sched/sched/sched_waitid.c b/sched/sched/sched_waitid.c
index 0dcbb087fe0ff..22188f5755626 100644
--- a/sched/sched/sched_waitid.c
+++ b/sched/sched/sched_waitid.c
@@ -152,6 +152,7 @@ int waitid(idtype_t idtype, id_t id, FAR siginfo_t *info, int options)
   FAR struct child_status_s *child;
   bool retains;
 #endif
+  irqstate_t flags;
   sigset_t set;
   int errcode;
   int ret;
@@ -198,18 +199,7 @@ int waitid(idtype_t idtype, id_t id, FAR siginfo_t *info, int options)
 
   sigemptyset(&set);
   nxsig_addset(&set, SIGCHLD);
-
-  /* NOTE: sched_lock() is not enough for SMP
-   * because the child task is running on another CPU
-   */
-
-#ifdef CONFIG_SMP
-  irqstate_t flags = enter_critical_section();
-#else
-  /* Disable pre-emption so that nothing changes while the loop executes */
-
-  sched_lock();
-#endif
+  flags = enter_critical_section();
 
   /* Verify that this task actually has children and that the requested
    * TCB is actually a child of this task.
@@ -464,20 +454,12 @@ int waitid(idtype_t idtype, id_t id, FAR siginfo_t *info, int options)
         }
     }
 
-#ifdef CONFIG_SMP
   leave_critical_section(flags);
-#else
-  sched_unlock();
-#endif
   leave_cancellation_point();
   return OK;
 
 errout:
-#ifdef CONFIG_SMP
   leave_critical_section(flags);
-#else
-  sched_unlock();
-#endif
   leave_cancellation_point();
   set_errno(errcode);
   return ERROR;
diff --git a/sched/sched/sched_waitpid.c b/sched/sched/sched_waitpid.c
index 078a35a7bafc7..ff77a83e44c66 100644
--- a/sched/sched/sched_waitpid.c
+++ b/sched/sched/sched_waitpid.c
@@ -101,13 +101,7 @@ pid_t nxsched_waitpid(pid_t pid, int *stat_loc, int options)
    * because the child task is running on another CPU
    */
 
-#ifdef CONFIG_SMP
   irqstate_t flags = enter_critical_section();
-#else
-  /* Disable pre-emption so that nothing changes in the following tests */
-
-  sched_lock();
-#endif
 
   /* Get the TCB corresponding to this PID */
 
@@ -198,12 +192,7 @@ pid_t nxsched_waitpid(pid_t pid, int *stat_loc, int options)
   ret = pid;
 
 errout:
-#ifdef CONFIG_SMP
   leave_critical_section(flags);
-#else
-  sched_unlock();
-#endif
-
   return ret;
 }
 
@@ -230,6 +219,7 @@ pid_t nxsched_waitpid(pid_t pid, int *stat_loc, int options)
   bool retains;
 #endif
   FAR struct siginfo info;
+  irqstate_t flags;
   sigset_t set;
   int ret;
 
@@ -237,18 +227,7 @@ pid_t nxsched_waitpid(pid_t pid, int *stat_loc, int options)
 
   sigemptyset(&set);
   nxsig_addset(&set, SIGCHLD);
-
-  /* NOTE: sched_lock() is not enough for SMP
-   * because the child task is running on another CPU
-   */
-
-#ifdef CONFIG_SMP
-  irqstate_t flags = enter_critical_section();
-#else
-  /* Disable pre-emption so that nothing changes while the loop executes */
-
-  sched_lock();
-#endif
+  flags = enter_critical_section();
 
   /* Verify that this task actually has children and that the requested PID
    * is actually a child of this task.
@@ -495,12 +474,7 @@ pid_t nxsched_waitpid(pid_t pid, int *stat_loc, int options)
   ret = pid;
 
 errout:
-#ifdef CONFIG_SMP
   leave_critical_section(flags);
-#else
-  sched_unlock();
-#endif
-
   return ret;
 }
 #endif /* CONFIG_SCHED_HAVE_PARENT */