tracehook: clone

This moves all the ptrace initialization and tracing logic for task
creation into tracehook.h and ptrace.h inlines.  It reorganizes the code
slightly, but should not change any behavior.

There are four tracehook entry points, at each important stage of task
creation.  This keeps the interface from the core fork.c code fairly
clean, while supporting the complex setup required for ptrace or something
like it.

Signed-off-by: Roland McGrath <roland@redhat.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Reviewed-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 22 insertions, 0 deletions

diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h
index c74abfc4c7e8..dae6d85520fb 100644
--- a/include/linux/ptrace.h
+++ b/include/linux/ptrace.h
@@ -154,6 +154,28 @@ static inline int ptrace_event(int mask, int event, unsigned long message)
         return 1;
 }
 
+/**
+ * ptrace_init_task - initialize ptrace state for a new child
+ * @child:              new child task
+ * @ptrace:             true if child should be ptrace'd by parent's tracer
+ *
+ * This is called immediately after adding @child to its parent's children
+ * list.  @ptrace is false in the normal case, and true to ptrace @child.
+ *
+ * Called with current's siglock and write_lock_irq(&tasklist_lock) held.
+ */
+static inline void ptrace_init_task(struct task_struct *child, bool ptrace)
+{
+        INIT_LIST_HEAD(&child->ptrace_entry);
+        INIT_LIST_HEAD(&child->ptraced);
+        child->parent = child->real_parent;
+        child->ptrace = 0;
+        if (unlikely(ptrace)) {
+                child->ptrace = current->ptrace;
+                __ptrace_link(child, current->parent);
+        }
+}
+
 #ifndef force_successful_syscall_return
 /*
  * System call handlers that, upon successful completion, need to return a