sched: Add TASK_ANY for wait_task_inactive()

Now that wait_task_inactive()'s @match_state argument is a mask (like
ttwu()) it is possible to replace the special !match_state case with
an 'all-states' value such that any blocked state will match.

Suggested-by: Ingo Molnar (mingo@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/YxhkzfuFTvRnpUaH@hirez.programming.kicks-ass.net

diff --git a/drivers/powercap/idle_inject.c b/drivers/powercap/idle_inject.c
index a20bf12..999e218 100644 (file)
--- a/drivers/powercap/idle_inject.c
+++ b/drivers/powercap/idle_inject.c
@@ -254,7 +254,7 @@ void idle_inject_stop(struct idle_inject_device *ii_dev)
                iit = per_cpu_ptr(&idle_inject_thread, cpu);
                iit->should_run = 0;
 
-               wait_task_inactive(iit->tsk, 0);
+               wait_task_inactive(iit->tsk, TASK_ANY);
        }
 
        cpu_hotplug_enable();

diff --git a/fs/coredump.c b/fs/coredump.c
index 9f4aae2..3d9054c 100644 (file)
--- a/fs/coredump.c
+++ b/fs/coredump.c
@@ -412,7 +412,7 @@ static int coredump_wait(int exit_code, struct core_state *core_state)
                 */
                ptr = core_state->dumper.next;
                while (ptr != NULL) {
-                       wait_task_inactive(ptr->task, 0);
+                       wait_task_inactive(ptr->task, TASK_ANY);
                        ptr = ptr->next;
                }
        }

diff --git a/include/linux/sched.h b/include/linux/sched.h
index e7b2f8a..0facaad 100644 (file)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -101,6 +101,8 @@ struct task_group;
 #define TASK_RTLOCK_WAIT               0x1000
 #define TASK_STATE_MAX                 0x2000
 
+#define TASK_ANY                       (TASK_STATE_MAX-1)
+
 /* Convenience macros for the sake of set_current_state: */
 #define TASK_KILLABLE                  (TASK_WAKEKILL | TASK_UNINTERRUPTIBLE)
 #define TASK_STOPPED                   (TASK_WAKEKILL | __TASK_STOPPED)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 43d71c6..ea26526 100644 (file)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3253,12 +3253,12 @@ out:
 /*
  * wait_task_inactive - wait for a thread to unschedule.
  *
- * If @match_state is nonzero, it's the @p->state value just checked and
- * not expected to change.  If it changes, i.e. @p might have woken up,
- * then return zero.  When we succeed in waiting for @p to be off its CPU,
- * we return a positive number (its total switch count).  If a second call
- * a short while later returns the same number, the caller can be sure that
- * @p has remained unscheduled the whole time.
+ * Wait for the thread to block in any of the states set in @match_state.
+ * If it changes, i.e. @p might have woken up, then return zero.  When we
+ * succeed in waiting for @p to be off its CPU, we return a positive number
+ * (its total switch count).  If a second call a short while later returns the
+ * same number, the caller can be sure that @p has remained unscheduled the
+ * whole time.
  *
  * The caller must ensure that the task *will* unschedule sometime soon,
  * else this function might spin for a *long* time. This function can't
@@ -3294,7 +3294,7 @@ unsigned long wait_task_inactive(struct task_struct *p, unsigned int match_state
                 * is actually now running somewhere else!
                 */
                while (task_on_cpu(rq, p)) {
-                       if (match_state && !(READ_ONCE(p->__state) & match_state))
+                       if (!(READ_ONCE(p->__state) & match_state))
                                return 0;
                        cpu_relax();
                }
@@ -3309,7 +3309,7 @@ unsigned long wait_task_inactive(struct task_struct *p, unsigned int match_state
                running = task_on_cpu(rq, p);
                queued = task_on_rq_queued(p);
                ncsw = 0;
-               if (!match_state || (READ_ONCE(p->__state) & match_state))
+               if (READ_ONCE(p->__state) & match_state)
                        ncsw = p->nvcsw | LONG_MIN; /* sets MSB */
                task_rq_unlock(rq, p, &rf);