ptrace: introduce signal_wake_up_state() and ptrace_signal_wake_up()

Cleanup and preparation for the next change.

signal_wake_up(resume => true) is overused. None of ptrace/jctl callers
actually want to wakeup a TASK_WAKEKILL task, but they can't specify the
necessary mask.

Turn signal_wake_up() into signal_wake_up_state(state), reintroduce
signal_wake_up() as a trivial helper, and add ptrace_signal_wake_up()
which adds __TASK_TRACED.

This way ptrace_signal_wake_up() can work "inside" ptrace_request()
even if the tracee doesn't have the TASK_WAKEKILL bit set.

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

3 files changed, 18 insertions, 15 deletions

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 6fc8f45de4e9..d2112477ff5e 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2714,7 +2714,16 @@ static inline void thread_group_cputime_init(struct signal_struct *sig)
 extern void recalc_sigpending_and_wake(struct task_struct *t);
 extern void recalc_sigpending(void);
 
-extern void signal_wake_up(struct task_struct *t, int resume_stopped);
+extern void signal_wake_up_state(struct task_struct *t, unsigned int state);
+
+static inline void signal_wake_up(struct task_struct *t, bool resume)
+{
+        signal_wake_up_state(t, resume ? TASK_WAKEKILL : 0);
+}
+static inline void ptrace_signal_wake_up(struct task_struct *t, bool resume)
+{
+        signal_wake_up_state(t, resume ? __TASK_TRACED : 0);
+}
 
 /*
  * Wrappers for p->thread_info->cpu access. No-op on UP.
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 612a56126851..62f7c2774b16 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -117,7 +117,7 @@ void __ptrace_unlink(struct task_struct *child)
          * TASK_KILLABLE sleeps.
          */
         if (child->jobctl & JOBCTL_STOP_PENDING || task_is_traced(child))
-                signal_wake_up(child, task_is_traced(child));
+                ptrace_signal_wake_up(child, true);
 
         spin_unlock(&child->sighand->siglock);
 }
@@ -317,7 +317,7 @@ static int ptrace_attach(struct task_struct *task, long request,
          */
         if (task_is_stopped(task) &&
             task_set_jobctl_pending(task, JOBCTL_TRAP_STOP | JOBCTL_TRAPPING))
-                signal_wake_up(task, 1);
+                signal_wake_up_state(task, __TASK_STOPPED);
 
         spin_unlock(&task->sighand->siglock);
 
@@ -737,7 +737,7 @@ int ptrace_request(struct task_struct *child, long request,
                  * tracee into STOP.
                  */
                 if (likely(task_set_jobctl_pending(child, JOBCTL_TRAP_STOP)))
-                        signal_wake_up(child, child->jobctl & JOBCTL_LISTENING);
+                        ptrace_signal_wake_up(child, child->jobctl & JOBCTL_LISTENING);
 
                 unlock_task_sighand(child, &flags);
                 ret = 0;
@@ -763,7 +763,7 @@ int ptrace_request(struct task_struct *child, long request,
                          * start of this trap and now.  Trigger re-trap.
                          */
                         if (child->jobctl & JOBCTL_TRAP_NOTIFY)
-                                signal_wake_up(child, true);
+                                ptrace_signal_wake_up(child, true);
                         ret = 0;
                 }
                 unlock_task_sighand(child, &flags);
diff --git a/kernel/signal.c b/kernel/signal.c
index 53cd5c4d1172..6e97aa6fa32c 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -680,23 +680,17 @@ int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
  * No need to set need_resched since signal event passing
  * goes through ->blocked
  */
-void signal_wake_up(struct task_struct *t, int resume)
+void signal_wake_up_state(struct task_struct *t, unsigned int state)
 {
-        unsigned int mask;
-
         set_tsk_thread_flag(t, TIF_SIGPENDING);
-
         /*
-         * For SIGKILL, we want to wake it up in the stopped/traced/killable
+         * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
          * case. We don't check t->state here because there is a race with it
          * executing another processor and just now entering stopped state.
          * By using wake_up_state, we ensure the process will wake up and
          * handle its death signal.
          */
-        mask = TASK_INTERRUPTIBLE;
-        if (resume)
-                mask |= TASK_WAKEKILL;
-        if (!wake_up_state(t, mask))
+        if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
                 kick_process(t);
 }
 
@@ -844,7 +838,7 @@ static void ptrace_trap_notify(struct task_struct *t)
         assert_spin_locked(&t->sighand->siglock);
 
         task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
-        signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
+        ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
 }
 
 /*