mm_for_maps: shift down_read(mmap_sem) to the caller

[safe/jmp/linux-2.6] / fs / proc / base.c

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 917f338..f3c2e40 100644 (file)
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -235,9 +235,8 @@ static int check_mem_permission(struct task_struct *task)
 struct mm_struct *mm_for_maps(struct task_struct *task)
 {
        struct mm_struct *mm = get_task_mm(task);
-       if (!mm)
-               return NULL;
-       if (mm != current->mm) {
+
+       if (mm && mm != current->mm) {
                /*
                 * task->mm can be changed before security check,
                 * in that case we must notice the change after.
@@ -245,10 +244,9 @@ struct mm_struct *mm_for_maps(struct task_struct *task)
                if (!ptrace_may_access(task, PTRACE_MODE_READ) ||
                    mm != task->mm) {
                        mmput(mm);
-                       return NULL;
+                       mm = NULL;
                }
        }
-       down_read(&mm->mmap_sem);
        return mm;
 }