RK3368 DDR: new ddr change freq method

[firefly-linux-kernel-4.4.55.git] / kernel / ptrace.c

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index afadcf7b4a22ddcdfd5b26993f892d8dd0eae653..118323bc852982de01c839b4bcbe32e22fbe4105 100644 (file)
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -720,6 +720,8 @@ static int ptrace_peek_siginfo(struct task_struct *child,
 static int ptrace_resume(struct task_struct *child, long request,
                         unsigned long data)
 {
+       bool need_siglock;
+
        if (!valid_signal(data))
                return -EIO;
 
@@ -747,8 +749,26 @@ static int ptrace_resume(struct task_struct *child, long request,
                user_disable_single_step(child);
        }
 
+       /*
+        * Change ->exit_code and ->state under siglock to avoid the race
+        * with wait_task_stopped() in between; a non-zero ->exit_code will
+        * wrongly look like another report from tracee.
+        *
+        * Note that we need siglock even if ->exit_code == data and/or this
+        * status was not reported yet, the new status must not be cleared by
+        * wait_task_stopped() after resume.
+        *
+        * If data == 0 we do not care if wait_task_stopped() reports the old
+        * status and clears the code too; this can't race with the tracee, it
+        * takes siglock after resume.
+        */
+       need_siglock = data && !thread_group_empty(current);
+       if (need_siglock)
+               spin_lock_irq(&child->sighand->siglock);
        child->exit_code = data;
        wake_up_state(child, __TASK_TRACED);
+       if (need_siglock)
+               spin_unlock_irq(&child->sighand->siglock);
 
        return 0;
 }