sched/wake_q: Clarify queue reinit comment

[mirror_ubuntu-bionic-kernel.git] / include / linux / sched.h

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 4d1905245c7aa50df56acf0f77c77f3347c28c04..1cc0dede21229be688f880c4eb40dc940620fecc 100644 (file)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -227,7 +227,7 @@ extern void proc_sched_set_task(struct task_struct *p);
 extern char ___assert_task_state[1 - 2*!!(
                sizeof(TASK_STATE_TO_CHAR_STR)-1 != ilog2(TASK_STATE_MAX)+1)];
 
-/* Convenience macros for the sake of set_task_state */
+/* Convenience macros for the sake of set_current_state */
 #define TASK_KILLABLE          (TASK_WAKEKILL | TASK_UNINTERRUPTIBLE)
 #define TASK_STOPPED           (TASK_WAKEKILL | __TASK_STOPPED)
 #define TASK_TRACED            (TASK_WAKEKILL | __TASK_TRACED)
@@ -254,17 +254,6 @@ extern char ___assert_task_state[1 - 2*!!(
 
 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
 
-#define __set_task_state(tsk, state_value)                     \
-       do {                                                    \
-               (tsk)->task_state_change = _THIS_IP_;           \
-               (tsk)->state = (state_value);                   \
-       } while (0)
-#define set_task_state(tsk, state_value)                       \
-       do {                                                    \
-               (tsk)->task_state_change = _THIS_IP_;           \
-               smp_store_mb((tsk)->state, (state_value));      \
-       } while (0)
-
 #define __set_current_state(state_value)                       \
        do {                                                    \
                current->task_state_change = _THIS_IP_;         \
@@ -277,20 +266,6 @@ extern char ___assert_task_state[1 - 2*!!(
        } while (0)
 
 #else
-
-/*
- * @tsk had better be current, or you get to keep the pieces.
- *
- * The only reason is that computing current can be more expensive than
- * using a pointer that's already available.
- *
- * Therefore, see set_current_state().
- */
-#define __set_task_state(tsk, state_value)             \
-       do { (tsk)->state = (state_value); } while (0)
-#define set_task_state(tsk, state_value)               \
-       smp_store_mb((tsk)->state, (state_value))
-
 /*
  * set_current_state() includes a barrier so that the write of current->state
  * is correctly serialised wrt the caller's subsequent test of whether to
@@ -854,6 +829,16 @@ struct signal_struct {
 
 #define SIGNAL_UNKILLABLE      0x00000040 /* for init: ignore fatal signals */
 
+#define SIGNAL_STOP_MASK (SIGNAL_CLD_MASK | SIGNAL_STOP_STOPPED | \
+                         SIGNAL_STOP_CONTINUED)
+
+static inline void signal_set_stop_flags(struct signal_struct *sig,
+                                        unsigned int flags)
+{
+       WARN_ON(sig->flags & (SIGNAL_GROUP_EXIT|SIGNAL_GROUP_COREDUMP));
+       sig->flags = (sig->flags & ~SIGNAL_STOP_MASK) | flags;
+}
+
 /* If true, all threads except ->group_exit_task have pending SIGKILL */
 static inline int signal_group_exit(const struct signal_struct *sig)
 {
@@ -1015,8 +1000,8 @@ enum cpu_idle_type {
  *
  * The DEFINE_WAKE_Q macro declares and initializes the list head.
  * wake_up_q() does NOT reinitialize the list; it's expected to be
- * called near the end of a function, where the fact that the queue is
- * not used again will be easy to see by inspection.
+ * called near the end of a function. Otherwise, the list can be
+ * re-initialized for later re-use by wake_q_init().
  *
  * Note that this can cause spurious wakeups. schedule() callers
  * must ensure the call is done inside a loop, confirming that the
@@ -1036,6 +1021,12 @@ struct wake_q_head {
 #define DEFINE_WAKE_Q(name)                            \
        struct wake_q_head name = { WAKE_Q_TAIL, &name.first }
 
+static inline void wake_q_init(struct wake_q_head *head)
+{
+       head->first = WAKE_Q_TAIL;
+       head->lastp = &head->first;
+}
+
 extern void wake_q_add(struct wake_q_head *head,
                       struct task_struct *task);
 extern void wake_up_q(struct wake_q_head *head);