job control: rename signal->group_stop and flags to jobctl and update them

signal->group_stop currently hosts mostly group stop related flags;
however, it's gonna be used for wider purposes and the GROUP_STOP_
flag prefix becomes confusing.  Rename signal->group_stop to
signal->jobctl and rename all GROUP_STOP_* flags to JOBCTL_*.

Bit position macros JOBCTL_*_BIT are defined and JOBCTL_* flags are
defined in terms of them to allow using bitops later.

While at it, reassign JOBCTL_TRAPPING to bit 22 to better accomodate
future additions.

This doesn't cause any functional change.

-v2: JOBCTL_*_BIT macros added as suggested by Linus.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>

1 files changed, 46 insertions, 45 deletions

diff --git a/kernel/signal.c b/kernel/signal.c
index 86c32b884f8e..ab6851c06461 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -124,7 +124,7 @@ static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
 
 static int recalc_sigpending_tsk(struct task_struct *t)
 {
-        if ((t->group_stop & GROUP_STOP_PENDING) ||
+        if ((t->jobctl & JOBCTL_STOP_PENDING) ||
             PENDING(&t->pending, &t->blocked) ||
             PENDING(&t->signal->shared_pending, &t->blocked)) {
                 set_tsk_thread_flag(t, TIF_SIGPENDING);
@@ -224,27 +224,28 @@ static inline void print_dropped_signal(int sig)
 }
 
 /**
- * task_clear_group_stop_trapping - clear group stop trapping bit
+ * task_clear_jobctl_trapping - clear jobctl trapping bit
  * @task: target task
  *
- * If GROUP_STOP_TRAPPING is set, a ptracer is waiting for us.  Clear it
- * and wake up the ptracer.  Note that we don't need any further locking.
- * @task->siglock guarantees that @task->parent points to the ptracer.
+ * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
+ * Clear it and wake up the ptracer.  Note that we don't need any further
+ * locking.  @task->siglock guarantees that @task->parent points to the
+ * ptracer.
  *
  * CONTEXT:
  * Must be called with @task->sighand->siglock held.
  */
-static void task_clear_group_stop_trapping(struct task_struct *task)
+static void task_clear_jobctl_trapping(struct task_struct *task)
 {
-        if (unlikely(task->group_stop & GROUP_STOP_TRAPPING)) {
-                task->group_stop &= ~GROUP_STOP_TRAPPING;
+        if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
+                task->jobctl &= ~JOBCTL_TRAPPING;
                 __wake_up_sync_key(&task->parent->signal->wait_chldexit,
                                    TASK_UNINTERRUPTIBLE, 1, task);
         }
 }
 
 /**
- * task_clear_group_stop_pending - clear pending group stop
+ * task_clear_jobctl_stop_pending - clear pending group stop
  * @task: target task
  *
  * Clear group stop states for @task.
@@ -252,19 +253,19 @@ static void task_clear_group_stop_trapping(struct task_struct *task)
  * CONTEXT:
  * Must be called with @task->sighand->siglock held.
  */
-void task_clear_group_stop_pending(struct task_struct *task)
+void task_clear_jobctl_stop_pending(struct task_struct *task)
 {
-        task->group_stop &= ~(GROUP_STOP_PENDING | GROUP_STOP_CONSUME |
-                              GROUP_STOP_DEQUEUED);
+        task->jobctl &= ~(JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME |
+                          JOBCTL_STOP_DEQUEUED);
 }
 
 /**
  * task_participate_group_stop - participate in a group stop
  * @task: task participating in a group stop
  *
- * @task has GROUP_STOP_PENDING set and is participating in a group stop.
+ * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
  * Group stop states are cleared and the group stop count is consumed if
- * %GROUP_STOP_CONSUME was set.  If the consumption completes the group
+ * %JOBCTL_STOP_CONSUME was set.  If the consumption completes the group
  * stop, the appropriate %SIGNAL_* flags are set.
  *
  * CONTEXT:
@@ -277,11 +278,11 @@ void task_clear_group_stop_pending(struct task_struct *task)
 static bool task_participate_group_stop(struct task_struct *task)
 {
         struct signal_struct *sig = task->signal;
-        bool consume = task->group_stop & GROUP_STOP_CONSUME;
+        bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
 
-        WARN_ON_ONCE(!(task->group_stop & GROUP_STOP_PENDING));
+        WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
 
-        task_clear_group_stop_pending(task);
+        task_clear_jobctl_stop_pending(task);
 
         if (!consume)
                 return false;
@@ -604,7 +605,7 @@ int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
                  * is to alert stop-signal processing code when another
                  * processor has come along and cleared the flag.
                  */
-                current->group_stop |= GROUP_STOP_DEQUEUED;
+                current->jobctl |= JOBCTL_STOP_DEQUEUED;
         }
         if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
                 /*
@@ -809,7 +810,7 @@ static int prepare_signal(int sig, struct task_struct *p, int from_ancestor_ns)
                 rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending);
                 t = p;
                 do {
-                        task_clear_group_stop_pending(t);
+                        task_clear_jobctl_stop_pending(t);
                         rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
                         wake_up_state(t, __TASK_STOPPED);
                 } while_each_thread(p, t);
@@ -925,7 +926,7 @@ static void complete_signal(int sig, struct task_struct *p, int group)
                         signal->group_stop_count = 0;
                         t = p;
                         do {
-                                task_clear_group_stop_pending(t);
+                                task_clear_jobctl_stop_pending(t);
                                 sigaddset(&t->pending.signal, SIGKILL);
                                 signal_wake_up(t, 1);
                         } while_each_thread(p, t);
@@ -1160,7 +1161,7 @@ int zap_other_threads(struct task_struct *p)
         p->signal->group_stop_count = 0;
 
         while_each_thread(p, t) {
-                task_clear_group_stop_pending(t);
+                task_clear_jobctl_stop_pending(t);
                 count++;
 
                 /* Don't bother with already dead threads */
@@ -1738,7 +1739,7 @@ static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
          * clear now.  We act as if SIGCONT is received after TASK_TRACED
          * is entered - ignore it.
          */
-        if (why == CLD_STOPPED && (current->group_stop & GROUP_STOP_PENDING))
+        if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
                 gstop_done = task_participate_group_stop(current);
 
         current->last_siginfo = info;
@@ -1751,12 +1752,12 @@ static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
         set_current_state(TASK_TRACED);
 
         /*
-         * We're committing to trapping.  Clearing GROUP_STOP_TRAPPING and
+         * We're committing to trapping.  Clearing JOBCTL_TRAPPING and
          * transition to TASK_TRACED should be atomic with respect to
-         * siglock.  This hsould be done after the arch hook as siglock is
+         * siglock.  This should be done after the arch hook as siglock is
          * released and regrabbed across it.
          */
-        task_clear_group_stop_trapping(current);
+        task_clear_jobctl_trapping(current);
 
         spin_unlock_irq(&current->sighand->siglock);
         read_lock(&tasklist_lock);
@@ -1792,9 +1793,9 @@ static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
                  *
                  * If @gstop_done, the ptracer went away between group stop
                  * completion and here.  During detach, it would have set
-                 * GROUP_STOP_PENDING on us and we'll re-enter TASK_STOPPED
-                 * in do_signal_stop() on return, so notifying the real
-                 * parent of the group stop completion is enough.
+                 * JOBCTL_STOP_PENDING on us and we'll re-enter
+                 * TASK_STOPPED in do_signal_stop() on return, so notifying
+                 * the real parent of the group stop completion is enough.
                  */
                 if (gstop_done)
                         do_notify_parent_cldstop(current, false, why);
@@ -1856,14 +1857,14 @@ static int do_signal_stop(int signr)
 {
         struct signal_struct *sig = current->signal;
 
-        if (!(current->group_stop & GROUP_STOP_PENDING)) {
-                unsigned int gstop = GROUP_STOP_PENDING | GROUP_STOP_CONSUME;
+        if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
+                unsigned int gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
                 struct task_struct *t;
 
-                /* signr will be recorded in task->group_stop for retries */
-                WARN_ON_ONCE(signr & ~GROUP_STOP_SIGMASK);
+                /* signr will be recorded in task->jobctl for retries */
+                WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
 
-                if (!likely(current->group_stop & GROUP_STOP_DEQUEUED) ||
+                if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
                     unlikely(signal_group_exit(sig)))
                         return 0;
                 /*
@@ -1890,19 +1891,19 @@ static int do_signal_stop(int signr)
                 else
                         WARN_ON_ONCE(!task_ptrace(current));
 
-                current->group_stop &= ~GROUP_STOP_SIGMASK;
-                current->group_stop |= signr | gstop;
+                current->jobctl &= ~JOBCTL_STOP_SIGMASK;
+                current->jobctl |= signr | gstop;
                 sig->group_stop_count = 1;
                 for (t = next_thread(current); t != current;
                      t = next_thread(t)) {
-                        t->group_stop &= ~GROUP_STOP_SIGMASK;
+                        t->jobctl &= ~JOBCTL_STOP_SIGMASK;
                         /*
                          * Setting state to TASK_STOPPED for a group
                          * stop is always done with the siglock held,
                          * so this check has no races.
                          */
                         if (!(t->flags & PF_EXITING) && !task_is_stopped(t)) {
-                                t->group_stop |= signr | gstop;
+                                t->jobctl |= signr | gstop;
                                 sig->group_stop_count++;
                                 signal_wake_up(t, 0);
                         }
@@ -1943,23 +1944,23 @@ retry:
 
                 spin_lock_irq(&current->sighand->siglock);
         } else {
-                ptrace_stop(current->group_stop & GROUP_STOP_SIGMASK,
+                ptrace_stop(current->jobctl & JOBCTL_STOP_SIGMASK,
                             CLD_STOPPED, 0, NULL);
                 current->exit_code = 0;
         }
 
         /*
-         * GROUP_STOP_PENDING could be set if another group stop has
+         * JOBCTL_STOP_PENDING could be set if another group stop has
          * started since being woken up or ptrace wants us to transit
          * between TASK_STOPPED and TRACED.  Retry group stop.
          */
-        if (current->group_stop & GROUP_STOP_PENDING) {
-                WARN_ON_ONCE(!(current->group_stop & GROUP_STOP_SIGMASK));
+        if (current->jobctl & JOBCTL_STOP_PENDING) {
+                WARN_ON_ONCE(!(current->jobctl & JOBCTL_STOP_SIGMASK));
                 goto retry;
         }
 
         /* PTRACE_ATTACH might have raced with task killing, clear trapping */
-        task_clear_group_stop_trapping(current);
+        task_clear_jobctl_trapping(current);
 
         spin_unlock_irq(&current->sighand->siglock);
 
@@ -2078,8 +2079,8 @@ relock:
                 if (unlikely(signr != 0))
                         ka = return_ka;
                 else {
-                        if (unlikely(current->group_stop &
-                                     GROUP_STOP_PENDING) && do_signal_stop(0))
+                        if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
+                            do_signal_stop(0))
                                 goto relock;
 
                         signr = dequeue_signal(current, &current->blocked,
@@ -2253,7 +2254,7 @@ void exit_signals(struct task_struct *tsk)
         signotset(&unblocked);
         retarget_shared_pending(tsk, &unblocked);
 
-        if (unlikely(tsk->group_stop & GROUP_STOP_PENDING) &&
+        if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
             task_participate_group_stop(tsk))
                 group_stop = CLD_STOPPED;
 out: