1 files changed, 74 insertions, 94 deletions

diff --git a/kernel/signal.c b/kernel/signal.c
index 64c5deeaca5d..6705320784fd 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -705,7 +705,7 @@ static int prepare_signal(int sig, struct task_struct *p, int from_ancestor_ns)
 
                 if (why) {
                         /*
-                         * The first thread which returns from finish_stop()
+                         * The first thread which returns from do_signal_stop()
                          * will take ->siglock, notice SIGNAL_CLD_MASK, and
                          * notify its parent. See get_signal_to_deliver().
                          */
@@ -971,6 +971,20 @@ specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
         return send_signal(sig, info, t, 0);
 }
 
+int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
+                        bool group)
+{
+        unsigned long flags;
+        int ret = -ESRCH;
+
+        if (lock_task_sighand(p, &flags)) {
+                ret = send_signal(sig, info, p, group);
+                unlock_task_sighand(p, &flags);
+        }
+
+        return ret;
+}
+
 /*
  * Force a signal that the process can't ignore: if necessary
  * we unblock the signal and change any SIG_IGN to SIG_DFL.
@@ -1036,12 +1050,6 @@ void zap_other_threads(struct task_struct *p)
         }
 }
 
-int __fatal_signal_pending(struct task_struct *tsk)
-{
-        return sigismember(&tsk->pending.signal, SIGKILL);
-}
-EXPORT_SYMBOL(__fatal_signal_pending);
-
 struct sighand_struct *lock_task_sighand(struct task_struct *tsk, unsigned long *flags)
 {
         struct sighand_struct *sighand;
@@ -1068,18 +1076,10 @@ struct sighand_struct *lock_task_sighand(struct task_struct *tsk, unsigned long
  */
 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
 {
-        unsigned long flags;
-        int ret;
+        int ret = check_kill_permission(sig, info, p);
 
-        ret = check_kill_permission(sig, info, p);
-
-        if (!ret && sig) {
-                ret = -ESRCH;
-                if (lock_task_sighand(p, &flags)) {
-                        ret = __group_send_sig_info(sig, info, p);
-                        unlock_task_sighand(p, &flags);
-                }
-        }
+        if (!ret && sig)
+                ret = do_send_sig_info(sig, info, p, true);
 
         return ret;
 }
@@ -1224,15 +1224,9 @@ static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
  * These are for backward compatibility with the rest of the kernel source.
  */
 
-/*
- * The caller must ensure the task can't exit.
- */
 int
 send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
 {
-        int ret;
-        unsigned long flags;
-
         /*
          * Make sure legacy kernel users don't send in bad values
          * (normal paths check this in check_kill_permission).
@@ -1240,10 +1234,7 @@ send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
         if (!valid_signal(sig))
                 return -EINVAL;
 
-        spin_lock_irqsave(&p->sighand->siglock, flags);
-        ret = specific_send_sig_info(sig, info, p);
-        spin_unlock_irqrestore(&p->sighand->siglock, flags);
-        return ret;
+        return do_send_sig_info(sig, info, p, false);
 }
 
 #define __si_special(priv) \
@@ -1383,15 +1374,6 @@ ret:
 }
 
 /*
- * Wake up any threads in the parent blocked in wait* syscalls.
- */
-static inline void __wake_up_parent(struct task_struct *p,
-                                    struct task_struct *parent)
-{
-        wake_up_interruptible_sync(&parent->signal->wait_chldexit);
-}
-
-/*
  * Let a parent know about the death of a child.
  * For a stopped/continued status change, use do_notify_parent_cldstop instead.
  *
@@ -1673,29 +1655,6 @@ void ptrace_notify(int exit_code)
         spin_unlock_irq(&current->sighand->siglock);
 }
 
-static void
-finish_stop(int stop_count)
-{
-        /*
-         * If there are no other threads in the group, or if there is
-         * a group stop in progress and we are the last to stop,
-         * report to the parent.  When ptraced, every thread reports itself.
-         */
-        if (tracehook_notify_jctl(stop_count == 0, CLD_STOPPED)) {
-                read_lock(&tasklist_lock);
-                do_notify_parent_cldstop(current, CLD_STOPPED);
-                read_unlock(&tasklist_lock);
-        }
-
-        do {
-                schedule();
-        } while (try_to_freeze());
-        /*
-         * Now we don't run again until continued.
-         */
-        current->exit_code = 0;
-}
-
 /*
  * This performs the stopping for SIGSTOP and other stop signals.
  * We have to stop all threads in the thread group.
@@ -1705,15 +1664,9 @@ finish_stop(int stop_count)
 static int do_signal_stop(int signr)
 {
         struct signal_struct *sig = current->signal;
-        int stop_count;
+        int notify;
 
-        if (sig->group_stop_count > 0) {
-                /*
-                 * There is a group stop in progress.  We don't need to
-                 * start another one.
-                 */
-                stop_count = --sig->group_stop_count;
-        } else {
+        if (!sig->group_stop_count) {
                 struct task_struct *t;
 
                 if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED) ||
@@ -1725,7 +1678,7 @@ static int do_signal_stop(int signr)
                  */
                 sig->group_exit_code = signr;
 
-                stop_count = 0;
+                sig->group_stop_count = 1;
                 for (t = next_thread(current); t != current; t = next_thread(t))
                         /*
                          * Setting state to TASK_STOPPED for a group
@@ -1734,19 +1687,44 @@ static int do_signal_stop(int signr)
                          */
                         if (!(t->flags & PF_EXITING) &&
                             !task_is_stopped_or_traced(t)) {
-                                stop_count++;
+                                sig->group_stop_count++;
                                 signal_wake_up(t, 0);
                         }
-                sig->group_stop_count = stop_count;
         }
+        /*
+         * If there are no other threads in the group, or if there is
+         * a group stop in progress and we are the last to stop, report
+         * to the parent.  When ptraced, every thread reports itself.
+         */
+        notify = sig->group_stop_count == 1 ? CLD_STOPPED : 0;
+        notify = tracehook_notify_jctl(notify, CLD_STOPPED);
+        /*
+         * tracehook_notify_jctl() can drop and reacquire siglock, so
+         * we keep ->group_stop_count != 0 before the call. If SIGCONT
+         * or SIGKILL comes in between ->group_stop_count == 0.
+         */
+        if (sig->group_stop_count) {
+                if (!--sig->group_stop_count)
+                        sig->flags = SIGNAL_STOP_STOPPED;
+                current->exit_code = sig->group_exit_code;
+                __set_current_state(TASK_STOPPED);
+        }
+        spin_unlock_irq(&current->sighand->siglock);
 
-        if (stop_count == 0)
-                sig->flags = SIGNAL_STOP_STOPPED;
-        current->exit_code = sig->group_exit_code;
-        __set_current_state(TASK_STOPPED);
+        if (notify) {
+                read_lock(&tasklist_lock);
+                do_notify_parent_cldstop(current, notify);
+                read_unlock(&tasklist_lock);
+        }
+
+        /* Now we don't run again until woken by SIGCONT or SIGKILL */
+        do {
+                schedule();
+        } while (try_to_freeze());
+
+        tracehook_finish_jctl();
+        current->exit_code = 0;
 
-        spin_unlock_irq(&current->sighand->siglock);
-        finish_stop(stop_count);
         return 1;
 }
 
@@ -1815,14 +1793,15 @@ relock:
                 int why = (signal->flags & SIGNAL_STOP_CONTINUED)
                                 ? CLD_CONTINUED : CLD_STOPPED;
                 signal->flags &= ~SIGNAL_CLD_MASK;
-                spin_unlock_irq(&sighand->siglock);
 
-                if (unlikely(!tracehook_notify_jctl(1, why)))
-                        goto relock;
+                why = tracehook_notify_jctl(why, CLD_CONTINUED);
+                spin_unlock_irq(&sighand->siglock);
 
-                read_lock(&tasklist_lock);
-                do_notify_parent_cldstop(current->group_leader, why);
-                read_unlock(&tasklist_lock);
+                if (why) {
+                        read_lock(&tasklist_lock);
+                        do_notify_parent_cldstop(current->group_leader, why);
+                        read_unlock(&tasklist_lock);
+                }
                 goto relock;
         }
 
@@ -1987,14 +1966,14 @@ void exit_signals(struct task_struct *tsk)
         if (unlikely(tsk->signal->group_stop_count) &&
                         !--tsk->signal->group_stop_count) {
                 tsk->signal->flags = SIGNAL_STOP_STOPPED;
-                group_stop = 1;
+                group_stop = tracehook_notify_jctl(CLD_STOPPED, CLD_STOPPED);
         }
 out:
         spin_unlock_irq(&tsk->sighand->siglock);
 
-        if (unlikely(group_stop) && tracehook_notify_jctl(1, CLD_STOPPED)) {
+        if (unlikely(group_stop)) {
                 read_lock(&tasklist_lock);
-                do_notify_parent_cldstop(tsk, CLD_STOPPED);
+                do_notify_parent_cldstop(tsk, group_stop);
                 read_unlock(&tasklist_lock);
         }
 }
@@ -2290,7 +2269,6 @@ static int
 do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
 {
         struct task_struct *p;
-        unsigned long flags;
         int error = -ESRCH;
 
         rcu_read_lock();
@@ -2300,14 +2278,16 @@ do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
                 /*
                  * The null signal is a permissions and process existence
                  * probe.  No signal is actually delivered.
-                 *
-                 * If lock_task_sighand() fails we pretend the task dies
-                 * after receiving the signal. The window is tiny, and the
-                 * signal is private anyway.
                  */
-                if (!error && sig && lock_task_sighand(p, &flags)) {
-                        error = specific_send_sig_info(sig, info, p);
-                        unlock_task_sighand(p, &flags);
+                if (!error && sig) {
+                        error = do_send_sig_info(sig, info, p, false);
+                        /*
+                         * If lock_task_sighand() failed we pretend the task
+                         * dies after receiving the signal. The window is tiny,
+                         * and the signal is private anyway.
+                         */
+                        if (unlikely(error == -ESRCH))
+                                error = 0;
                 }
         }
         rcu_read_unlock();