taskstats: remove initialization of static per-cpu variable

[GitHub/mt8127/android_kernel_alcatel_ttab.git] / kernel / ptrace.c

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 6c19e94fd0a5482786e432599a0fb4840a5c66cb..8392a9da64504054bf804e5809f902bc296f676f 100644 (file)
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -33,13 +33,9 @@
  */
 void __ptrace_link(struct task_struct *child, struct task_struct *new_parent)
 {
-       BUG_ON(!list_empty(&child->ptrace_list));
-       if (child->parent == new_parent)
-               return;
-       list_add(&child->ptrace_list, &child->parent->ptrace_children);
-       remove_parent(child);
+       BUG_ON(!list_empty(&child->ptrace_entry));
+       list_add(&child->ptrace_entry, &new_parent->ptraced);
        child->parent = new_parent;
-       add_parent(child);
 }
  
 /*
@@ -73,12 +69,8 @@ void __ptrace_unlink(struct task_struct *child)
        BUG_ON(!child->ptrace);
 
        child->ptrace = 0;
-       if (ptrace_reparented(child)) {
-               list_del_init(&child->ptrace_list);
-               remove_parent(child);
-               child->parent = child->real_parent;
-               add_parent(child);
-       }
+       child->parent = child->real_parent;
+       list_del_init(&child->ptrace_entry);
 
        if (task_is_traced(child))
                ptrace_untrace(child);
@@ -121,7 +113,7 @@ int ptrace_check_attach(struct task_struct *child, int kill)
        return ret;
 }
 
-int __ptrace_may_attach(struct task_struct *task)
+int __ptrace_may_access(struct task_struct *task, unsigned int mode)
 {
        /* May we inspect the given task?
         * This check is used both for attaching with ptrace
@@ -148,16 +140,16 @@ int __ptrace_may_attach(struct task_struct *task)
        if (!dumpable && !capable(CAP_SYS_PTRACE))
                return -EPERM;
 
-       return security_ptrace(current, task);
+       return security_ptrace(current, task, mode);
 }
 
-int ptrace_may_attach(struct task_struct *task)
+bool ptrace_may_access(struct task_struct *task, unsigned int mode)
 {
        int err;
        task_lock(task);
-       err = __ptrace_may_attach(task);
+       err = __ptrace_may_access(task, mode);
        task_unlock(task);
-       return !err;
+       return (!err ? true : false);
 }
 
 int ptrace_attach(struct task_struct *task)
@@ -195,7 +187,7 @@ repeat:
        /* the same process cannot be attached many times */
        if (task->ptrace & PT_PTRACED)
                goto bad;
-       retval = __ptrace_may_attach(task);
+       retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH);
        if (retval)
                goto bad;
 
@@ -492,14 +484,34 @@ int ptrace_traceme(void)
        /*
         * Are we already being traced?
         */
+repeat:
        task_lock(current);
        if (!(current->ptrace & PT_PTRACED)) {
-               ret = security_ptrace(current->parent, current);
+               /*
+                * See ptrace_attach() comments about the locking here.
+                */
+               unsigned long flags;
+               if (!write_trylock_irqsave(&tasklist_lock, flags)) {
+                       task_unlock(current);
+                       do {
+                               cpu_relax();
+                       } while (!write_can_lock(&tasklist_lock));
+                       goto repeat;
+               }
+
+               ret = security_ptrace(current->parent, current,
+                                     PTRACE_MODE_ATTACH);
+
                /*
                 * Set the ptrace bit in the process ptrace flags.
+                * Then link us on our parent's ptraced list.
                 */
-               if (!ret)
+               if (!ret) {
                        current->ptrace |= PT_PTRACED;
+                       __ptrace_link(current, current->real_parent);
+               }
+
+               write_unlock_irqrestore(&tasklist_lock, flags);
        }
        task_unlock(current);
        return ret;