diff --git a/gdb/infrun.c b/gdb/infrun.c
index bf0632e..87b358f 100644
--- a/gdb/infrun.c
+++ b/gdb/infrun.c
@@ -2081,6 +2081,8 @@
       step_over_what step_what;
       int must_be_in_line;
 
+      gdb_assert (!tp->stop_requested);
+
       next = thread_step_over_chain_next (tp);
 
       /* If this inferior already has a displaced step in process,
@@ -2329,6 +2331,8 @@
 {
   struct thread_info *tp = inferior_thread ();
 
+  gdb_assert (!tp->stop_requested);
+
   /* Install inferior's terminal modes.  */
   target_terminal_inferior ();
 
@@ -2393,6 +2397,7 @@
      single-step).  */
   int step;
 
+  gdb_assert (!tp->stop_requested);
   gdb_assert (!thread_is_in_step_over_chain (tp));
 
   QUIT;
@@ -3274,65 +3279,6 @@
 static void process_event_stop_test (struct execution_control_state *ecs);
 static int switch_back_to_stepped_thread (struct execution_control_state *ecs);
 
-/* Callback for iterate over threads.  If the thread is stopped, but
-   the user/frontend doesn't know about that yet, go through
-   normal_stop, as if the thread had just stopped now.  ARG points at
-   a ptid.  If PTID is MINUS_ONE_PTID, applies to all threads.  If
-   ptid_is_pid(PTID) is true, applies to all threads of the process
-   pointed at by PTID.  Otherwise, apply only to the thread pointed by
-   PTID.  */
-
-static int
-infrun_thread_stop_requested_callback (struct thread_info *info, void *arg)
-{
-  ptid_t ptid = * (ptid_t *) arg;
-
-  if ((ptid_equal (info->ptid, ptid)
-       || ptid_equal (minus_one_ptid, ptid)
-       || (ptid_is_pid (ptid)
-	   && ptid_get_pid (ptid) == ptid_get_pid (info->ptid)))
-      && is_running (info->ptid)
-      && !is_executing (info->ptid))
-    {
-      struct cleanup *old_chain;
-      struct execution_control_state ecss;
-      struct execution_control_state *ecs = &ecss;
-
-      memset (ecs, 0, sizeof (*ecs));
-
-      old_chain = make_cleanup_restore_current_thread ();
-
-      overlay_cache_invalid = 1;
-      /* Flush target cache before starting to handle each event.
-	 Target was running and cache could be stale.  This is just a
-	 heuristic.  Running threads may modify target memory, but we
-	 don't get any event.  */
-      target_dcache_invalidate ();
-
-      /* Go through handle_inferior_event/normal_stop, so we always
-	 have consistent output as if the stop event had been
-	 reported.  */
-      ecs->ptid = info->ptid;
-      ecs->event_thread = info;
-      ecs->ws.kind = TARGET_WAITKIND_STOPPED;
-      ecs->ws.value.sig = GDB_SIGNAL_0;
-
-      handle_inferior_event (ecs);
-
-      if (!ecs->wait_some_more)
-	{
-	  /* Cancel any running execution command.  */
-	  thread_cancel_execution_command (info);
-
-	  normal_stop ();
-	}
-
-      do_cleanups (old_chain);
-    }
-
-  return 0;
-}
-
 /* This function is attached as a "thread_stop_requested" observer.
    Cleanup local state that assumed the PTID was to be resumed, and
    report the stop to the frontend.  */
@@ -3342,17 +3288,51 @@
 {
   struct thread_info *tp;
 
-  /* PTID was requested to stop.  Remove matching threads from the
-     step-over queue, so we don't try to resume them
-     automatically.  */
+  /* PTID was requested to stop.  If the thread was already stopped,
+     but the user/frontend doesn't know about that yet (e.g., the
+     thread had been temporarily paused for some step-over), set up
+     for reporting the stop now.  */
   ALL_NON_EXITED_THREADS (tp)
     if (ptid_match (tp->ptid, ptid))
       {
+	if (tp->state != THREAD_RUNNING)
+	  continue;
+	if (tp->executing)
+	  continue;
+
+	/* Remove matching threads from the step-over queue, so
+	   start_step_over doesn't try to resume them
+	   automatically.  */
 	if (thread_is_in_step_over_chain (tp))
 	  thread_step_over_chain_remove (tp);
-      }
 
-  iterate_over_threads (infrun_thread_stop_requested_callback, &ptid);
+	/* If the thread is stopped, but the user/frontend doesn't
+	   know about that yet, queue a pending event, as if the
+	   thread had just stopped now.  Unless the thread already had
+	   a pending event.  */
+	if (!tp->suspend.waitstatus_pending_p)
+	  {
+	    tp->suspend.waitstatus_pending_p = 1;
+	    tp->suspend.waitstatus.kind = TARGET_WAITKIND_STOPPED;
+	    tp->suspend.waitstatus.value.sig = GDB_SIGNAL_0;
+	  }
+
+	/* Clear the inline-frame state, since we're re-processing the
+	   stop.  */
+	clear_inline_frame_state (tp->ptid);
+
+	/* If this thread was paused because some other thread was
+	   doing an inline-step over, let that finish first.  Once
+	   that happens, we'll restart all threads and consume pending
+	   stop events then.  */
+	if (step_over_info_valid_p ())
+	  continue;
+
+	/* Otherwise we can process the (new) pending event now.  Set
+	   it so this pending event is considered by
+	   do_target_wait.  */
+	tp->resumed = 1;
+      }
 }
 
 static void
@@ -4254,6 +4234,8 @@
   return 0;
 }
 
+static int handle_stop_requested (struct execution_control_state *ecs);
+
 /* Auxiliary function that handles syscall entry/return events.
    It returns 1 if the inferior should keep going (and GDB
    should ignore the event), or 0 if the event deserves to be
@@ -4283,6 +4265,9 @@
 	= bpstat_stop_status (get_regcache_aspace (regcache),
 			      stop_pc, ecs->ptid, &ecs->ws);
 
+      if (handle_stop_requested (ecs))
+	return 0;
+
       if (bpstat_causes_stop (ecs->event_thread->control.stop_bpstat))
 	{
 	  /* Catchpoint hit.  */
@@ -4290,6 +4275,9 @@
 	}
     }
 
+  if (handle_stop_requested (ecs))
+    return 0;
+
   /* If no catchpoint triggered for this, then keep going.  */
   keep_going (ecs);
   return 1;
@@ -4980,6 +4968,9 @@
 	    = bpstat_stop_status (get_regcache_aspace (regcache),
 				  stop_pc, ecs->ptid, &ecs->ws);
 
+	  if (handle_stop_requested (ecs))
+	    return;
+
 	  if (bpstat_causes_stop (ecs->event_thread->control.stop_bpstat))
 	    {
 	      /* A catchpoint triggered.  */
@@ -5034,6 +5025,8 @@
     case TARGET_WAITKIND_SPURIOUS:
       if (debug_infrun)
         fprintf_unfiltered (gdb_stdlog, "infrun: TARGET_WAITKIND_SPURIOUS\n");
+      if (handle_stop_requested (ecs))
+	return;
       if (!ptid_equal (ecs->ptid, inferior_ptid))
 	context_switch (ecs->ptid);
       resume (GDB_SIGNAL_0);
@@ -5043,6 +5036,8 @@
     case TARGET_WAITKIND_THREAD_CREATED:
       if (debug_infrun)
         fprintf_unfiltered (gdb_stdlog, "infrun: TARGET_WAITKIND_THREAD_CREATED\n");
+      if (handle_stop_requested (ecs))
+	return;
       if (!ptid_equal (ecs->ptid, inferior_ptid))
 	context_switch (ecs->ptid);
       if (!switch_back_to_stepped_thread (ecs))
@@ -5227,6 +5222,9 @@
 	= bpstat_stop_status (get_regcache_aspace (get_current_regcache ()),
 			      stop_pc, ecs->ptid, &ecs->ws);
 
+      if (handle_stop_requested (ecs))
+	return;
+
       /* If no catchpoint triggered for this, then keep going.  Note
 	 that we're interested in knowing the bpstat actually causes a
 	 stop, not just if it may explain the signal.  Software
@@ -5301,6 +5299,10 @@
 
       current_inferior ()->waiting_for_vfork_done = 0;
       current_inferior ()->pspace->breakpoints_not_allowed = 0;
+
+      if (handle_stop_requested (ecs))
+	return;
+
       /* This also takes care of reinserting breakpoints in the
 	 previously locked inferior.  */
       keep_going (ecs);
@@ -5337,6 +5339,9 @@
       xfree (ecs->ws.value.execd_pathname);
       ecs->ws.value.execd_pathname = NULL;
 
+      if (handle_stop_requested (ecs))
+	return;
+
       /* If no catchpoint triggered for this, then keep going.  */
       if (!bpstat_causes_stop (ecs->event_thread->control.stop_bpstat))
 	{
@@ -5374,7 +5379,6 @@
     case TARGET_WAITKIND_STOPPED:
       if (debug_infrun)
         fprintf_unfiltered (gdb_stdlog, "infrun: TARGET_WAITKIND_STOPPED\n");
-      ecs->event_thread->suspend.stop_signal = ecs->ws.value.sig;
       handle_signal_stop (ecs);
       return;
 
@@ -5391,6 +5395,10 @@
 
       delete_just_stopped_threads_single_step_breakpoints ();
       stop_pc = regcache_read_pc (get_thread_regcache (inferior_ptid));
+
+      if (handle_stop_requested (ecs))
+	return;
+
       observer_notify_no_history ();
       stop_waiting (ecs);
       return;
@@ -5480,6 +5488,8 @@
 	  continue;
 	}
 
+      gdb_assert (!tp->stop_requested);
+
       /* If some thread needs to start a step-over at this point, it
 	 should still be in the step-over queue, and thus skipped
 	 above.  */
@@ -5549,8 +5559,7 @@
 	 back an event.  */
       gdb_assert (ecs->event_thread->control.trap_expected);
 
-      if (ecs->event_thread->suspend.stop_signal == GDB_SIGNAL_TRAP)
-	clear_step_over_info ();
+      clear_step_over_info ();
     }
 
   if (!target_is_non_stop_p ())
@@ -5649,6 +5658,23 @@
   return 0;
 }
 
+/* If the event thread has the stop requested flag set, pretend it
+   stopped for a GDB_SIGNAL_0 (i.e., as if it stopped due to
+   target_stop).  */
+
+static int
+handle_stop_requested (struct execution_control_state *ecs)
+{
+  if (ecs->event_thread->stop_requested)
+    {
+      ecs->ws.kind = TARGET_WAITKIND_STOPPED;
+      ecs->ws.value.sig = GDB_SIGNAL_0;
+      handle_signal_stop (ecs);
+      return 1;
+    }
+  return 0;
+}
+
 /* Come here when the program has stopped with a signal.  */
 
 static void
@@ -5662,6 +5688,8 @@
 
   gdb_assert (ecs->ws.kind == TARGET_WAITKIND_STOPPED);
 
+  ecs->event_thread->suspend.stop_signal = ecs->ws.value.sig;
+
   /* Do we need to clean up the state of a thread that has
      completed a displaced single-step?  (Doing so usually affects
      the PC, so do it here, before we set stop_pc.)  */
@@ -6051,6 +6079,15 @@
   if (random_signal)
     random_signal = !stopped_by_watchpoint;
 
+  /* Always stop if the user explicitly requested this thread to
+     remain stopped.  */
+  if (ecs->event_thread->stop_requested)
+    {
+      random_signal = 1;
+      if (debug_infrun)
+	fprintf_unfiltered (gdb_stdlog, "infrun: user-requested stop\n");
+    }
+
   /* For the program's own signals, act according to
      the signal handling tables.  */
 
@@ -6097,8 +6134,6 @@
 	  && ecs->event_thread->control.trap_expected
 	  && ecs->event_thread->control.step_resume_breakpoint == NULL)
 	{
-	  int was_in_line;
-
 	  /* We were just starting a new sequence, attempting to
 	     single-step off of a breakpoint and expecting a SIGTRAP.
 	     Instead this signal arrives.  This signal will take us out
@@ -6114,34 +6149,11 @@
                                 "infrun: signal arrived while stepping over "
                                 "breakpoint\n");
 
-	  was_in_line = step_over_info_valid_p ();
-	  clear_step_over_info ();
 	  insert_hp_step_resume_breakpoint_at_frame (frame);
 	  ecs->event_thread->step_after_step_resume_breakpoint = 1;
 	  /* Reset trap_expected to ensure breakpoints are re-inserted.  */
 	  ecs->event_thread->control.trap_expected = 0;
 
-	  if (target_is_non_stop_p ())
-	    {
-	      /* Either "set non-stop" is "on", or the target is
-		 always in non-stop mode.  In this case, we have a bit
-		 more work to do.  Resume the current thread, and if
-		 we had paused all threads, restart them while the
-		 signal handler runs.  */
-	      keep_going (ecs);
-
-	      if (was_in_line)
-		{
-		  restart_threads (ecs->event_thread);
-		}
-	      else if (debug_infrun)
-		{
-		  fprintf_unfiltered (gdb_stdlog,
-				      "infrun: no need to restart threads\n");
-		}
-	      return;
-	    }
-
 	  /* If we were nexting/stepping some other thread, switch to
 	     it, so that we don't continue it, losing control.  */
 	  if (!switch_back_to_stepped_thread (ecs))
@@ -7682,8 +7694,6 @@
   if (debug_infrun)
     fprintf_unfiltered (gdb_stdlog, "infrun: stop_waiting\n");
 
-  clear_step_over_info ();
-
   /* Let callers know we don't want to wait for the inferior anymore.  */
   ecs->wait_some_more = 0;
 
diff --git a/gdb/testsuite/gdb.threads/interrupt-while-step-over.c b/gdb/testsuite/gdb.threads/interrupt-while-step-over.c
new file mode 100644
index 0000000..eeb81d4
--- /dev/null
+++ b/gdb/testsuite/gdb.threads/interrupt-while-step-over.c
@@ -0,0 +1,75 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2016 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include <pthread.h>
+#include <unistd.h>
+#include <stdlib.h>
+
+#define NUM_THREADS 20
+const int num_threads = NUM_THREADS;
+
+static pthread_t child_thread[NUM_THREADS];
+
+static pthread_barrier_t threads_started_barrier;
+
+volatile int always_zero;
+volatile unsigned int dummy;
+
+static void
+infinite_loop (void)
+{
+  while (1)
+    {
+      dummy++; /* set breakpoint here */
+    }
+}
+
+static void *
+child_function (void *arg)
+{
+  pthread_barrier_wait (&threads_started_barrier);
+
+  infinite_loop ();
+}
+
+void
+all_started (void)
+{
+}
+
+int
+main (void)
+{
+  int res;
+  int i;
+
+  alarm (300);
+
+  pthread_barrier_init (&threads_started_barrier, NULL, NUM_THREADS + 1);
+
+  for (i = 0; i < NUM_THREADS; i++)
+    {
+      res = pthread_create (&child_thread[i], NULL, child_function, NULL);
+    }
+
+  /* Wait until all threads have been scheduled.  */
+  pthread_barrier_wait (&threads_started_barrier);
+
+  all_started ();
+
+  infinite_loop ();
+}
diff --git a/gdb/testsuite/gdb.threads/interrupt-while-step-over.exp b/gdb/testsuite/gdb.threads/interrupt-while-step-over.exp
new file mode 100644
index 0000000..4407eb1
--- /dev/null
+++ b/gdb/testsuite/gdb.threads/interrupt-while-step-over.exp
@@ -0,0 +1,202 @@
+# Copyright (C) 2016 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# Regression test for PR gdb/18360.  Test that "interrupt -a" while
+# some thread is stepping over a breakpoint behaves as expected.
+
+standard_testfile
+
+if {[prepare_for_testing "failed to prepare" $testfile $srcfile \
+	 { debug pthreads }] == -1} {
+    return -1
+}
+
+# Read the number of threads out of the inferior.
+if ![runto_main] {
+    return -1
+}
+set NUM_THREADS [get_integer_valueof "num_threads" -1]
+
+# Account for the main thread.
+incr NUM_THREADS
+
+# Run command and wait for the prompt, without end anchor.
+
+proc gdb_test_no_anchor {cmd} {
+    global gdb_prompt
+
+    gdb_test_multiple $cmd $cmd {
+	-re "$gdb_prompt " {
+	    pass $cmd
+	}
+	-re "infrun:" {
+	    exp_continue
+	}
+    }
+}
+
+# Enable/disable debugging.
+
+proc enable_debug {enable} {
+
+    # Comment out to debug problems with the test.
+    return
+
+    gdb_test_no_anchor "set debug infrun $enable"
+    gdb_test_no_anchor "set debug displaced $enable"
+}
+
+# If RESULT is not zero, make the caller return RESULT.
+
+proc return_if_nonzero { result } {
+    if {$result != 0} {
+	return -code return $result
+    }
+}
+
+# Do one iteration of "c -a& -> interrupt -a".  Return zero on sucess,
+# and non-zero if some test fails.
+
+proc test_one_iteration {} {
+    global gdb_prompt
+    global NUM_THREADS
+    global decimal
+
+    set saw_continuing 0
+    set test "continue -a &"
+    return_if_nonzero [gdb_test_multiple $test $test {
+	-re "Continuing.\r\n" {
+	    set saw_continuing 1
+	    exp_continue
+	}
+	-re "$gdb_prompt " {
+	    if ![gdb_assert $saw_continuing $test] {
+		return 1
+	    }
+	}
+	-re "infrun:" {
+	    exp_continue
+	}
+    }]
+
+    set running_count 0
+    set test "all threads are running"
+    return_if_nonzero [gdb_test_multiple "info threads" $test {
+	-re "Thread \[^\r\n\]* \\(running\\)" {
+	    incr running_count
+	    exp_continue
+	}
+	-re "$gdb_prompt " {
+	    if ![gdb_assert {$running_count == $NUM_THREADS} $test] {
+		return 1
+	    }
+	}
+	-re "infrun:" {
+	    exp_continue
+	}
+    }]
+
+    set test "interrupt -a"
+    return_if_nonzero [gdb_test_multiple $test $test {
+	-re "$gdb_prompt " {
+	    pass $test
+	}
+	-re "infrun:" {
+	    exp_continue
+	}
+    }]
+
+    set stopped_count 0
+    set test "wait for stops"
+    # Don't return on failure here, in order to let "info threads" put
+    # useful info in gdb.log.
+    gdb_test_multiple "" $test {
+	-re "Thread $decimal \[^\r\n\]*stopped" {
+	    incr stopped_count
+	    if {$stopped_count != $NUM_THREADS} {
+		exp_continue
+	    }
+	}
+	-re "$gdb_prompt " {
+	    gdb_assert {$stopped_count == $NUM_THREADS} $test
+	}
+	-re "infrun:" {
+	    exp_continue
+	}
+    }
+
+    # Check if all threads are seen as stopped with "info
+    # threads".  It's a bit redundant with the test above, but
+    # it's useful to have this in the gdb.log if the above ever
+    # happens to fail.
+    set running_count 0
+    set test "all threads are stopped"
+    return_if_nonzero [gdb_test_multiple "info threads" $test {
+	-re "Thread \[^\r\n\]* \\(running\\)" {
+	    incr running_count
+	    exp_continue
+	}
+	-re "$gdb_prompt " {
+	    if ![gdb_assert {$running_count == 0} $test] {
+		return 1
+	    }
+	}
+    }]
+
+    return 0
+}
+
+# The test driver proper.  If DISPLACED is "on", turn on displaced
+# stepping.  If "off", turn it off.
+
+proc testdriver {displaced} {
+    global binfile
+    global GDBFLAGS
+
+    save_vars { GDBFLAGS } {
+	append GDBFLAGS " -ex \"set non-stop on\""
+	clean_restart $binfile
+    }
+
+    gdb_test_no_output "set displaced-stepping $displaced"
+
+    if ![runto all_started] {
+	fail "couldn't run to all_started"
+	return
+    }
+    set break_line [gdb_get_line_number "set breakpoint here"]
+
+    gdb_test "break $break_line if always_zero" "Breakpoint .*" "set breakpoint"
+
+    enable_debug 1
+
+    for {set iter 0} {$iter < 20} {incr iter} {
+	with_test_prefix "iter=$iter" {
+	    # Return early if some test fails, to avoid cascading
+	    # timeouts if something goes wrong.
+	    if {[test_one_iteration] != 0} {
+		return
+	    }
+	}
+    }
+}
+
+foreach_with_prefix displaced-stepping {"on" "off"} {
+    if { ${displaced-stepping} != "off" && ![support_displaced_stepping] } {
+	continue
+    }
+
+    testdriver ${displaced-stepping}
+}
diff --git a/gdb/testsuite/gdb.threads/signal-while-stepping-over-bp-other-thread.exp b/gdb/testsuite/gdb.threads/signal-while-stepping-over-bp-other-thread.exp
index 9e73015..ef894c2 100644
--- a/gdb/testsuite/gdb.threads/signal-while-stepping-over-bp-other-thread.exp
+++ b/gdb/testsuite/gdb.threads/signal-while-stepping-over-bp-other-thread.exp
@@ -100,7 +100,6 @@
     "need to step-over"
     "resume \\(step=1"
     "signal arrived while stepping over breakpoint"
-    "(restart threads|switching back to stepped thread)"
     "stepped to a different line"
     "callme"
 }