vserver 1.9.3

[linux-2.6.git] / kernel / ptrace.c

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 8b2856a..b14b4a4 100644 (file)
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -55,6 +55,15 @@ void __ptrace_unlink(task_t *child)
        REMOVE_LINKS(child);
        child->parent = child->real_parent;
        SET_LINKS(child);
+
+       if (child->state == TASK_TRACED) {
+               /*
+                * Turn a tracing stop into a normal stop now,
+                * since with no tracer there would be no way
+                * to wake it up with SIGCONT or SIGKILL.
+                */
+               child->state = TASK_STOPPED;
+       }
 }
 
 /*
@@ -62,20 +71,35 @@ void __ptrace_unlink(task_t *child)
  */
 int ptrace_check_attach(struct task_struct *child, int kill)
 {
-       if (!(child->ptrace & PT_PTRACED))
-               return -ESRCH;
+       int ret = -ESRCH;
 
-       if (child->parent != current)
-               return -ESRCH;
+       /*
+        * We take the read lock around doing both checks to close a
+        * possible race where someone else was tracing our child and
+        * detached between these two checks.  After this locked check,
+        * we are sure that this is our traced child and that can only
+        * be changed by us so it's not changing right after this.
+        */
+       read_lock(&tasklist_lock);
+       if ((child->ptrace & PT_PTRACED) && child->parent == current &&
+           child->signal != NULL) {
+               ret = 0;
+               spin_lock_irq(&child->sighand->siglock);
+               if (child->state == TASK_STOPPED) {
+                       child->state = TASK_TRACED;
+               } else if (child->state != TASK_TRACED && !kill) {
+                       ret = -ESRCH;
+               }
+               spin_unlock_irq(&child->sighand->siglock);
+       }
+       read_unlock(&tasklist_lock);
 
-       if (!kill) {
-               if (child->state != TASK_STOPPED)
-                       return -ESRCH;
+       if (!ret && !kill) {
                wait_task_inactive(child);
        }
 
        /* All systems go.. */
-       return 0;
+       return ret;
 }
 
 int ptrace_attach(struct task_struct *task)
@@ -178,8 +202,6 @@ int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, in
                if (bytes > PAGE_SIZE-offset)
                        bytes = PAGE_SIZE-offset;
 
-               flush_cache_page(vma, addr);
-
                maddr = kmap(page);
                if (write) {
                        copy_to_user_page(vma, page, addr,
@@ -322,24 +344,3 @@ int ptrace_request(struct task_struct *child, long request,
 
        return ret;
 }
-
-void ptrace_notify(int exit_code)
-{
-       BUG_ON (!(current->ptrace & PT_PTRACED));
-
-       /* Let the debugger run.  */
-       current->exit_code = exit_code;
-       set_current_state(TASK_STOPPED);
-       notify_parent(current, SIGCHLD);
-       schedule();
-
-       /*
-        * Signals sent while we were stopped might set TIF_SIGPENDING.
-        */
-
-       spin_lock_irq(&current->sighand->siglock);
-       recalc_sigpending();
-       spin_unlock_irq(&current->sighand->siglock);
-}
-
-EXPORT_SYMBOL(ptrace_notify);