The current logic does not work. Remove it. Now detach always does
UTRACE_DETACH and attach doesn't try to reuse the old engine.
This means ptrace_detach(sig) can't work correctly. But, before we
fix this problem, it is better to make other changes. In particular,
it makes sense to move ->last_siginfo and ->exit_code to engine->data.
As for ->exit_code, I mean that ptrace.c should not use ->exit_code
at all, instead we should have a member in engine->data.
---
--- PU/kernel/ptrace.c~05_ALWAYS_DETACH 2009-08-13 17:55:13.000000000 +0200
+++ PU/kernel/ptrace.c 2009-08-13 18:23:43.000000000 +0200
@@ -42,7 +42,6 @@ static const struct utrace_engine_ops pt
static void ptrace_detach_task(struct task_struct *child, int sig)
{
- enum utrace_resume_action action = UTRACE_DETACH;
struct utrace_engine *engine;
int ret;
@@ -51,19 +50,7 @@ static void ptrace_detach_task(struct ta
if (unlikely(IS_ERR(engine)))
return;
- /*
- * When leaving a parting signal to deliver, we cannot detach our
- * utrace engine yet. We need it there to get a report_signal()
- * callback that can inject our parting signal. Instead, we'll
- * mark our engine by clearing its data pointer. Our callbacks
- * will see this and know it's a PTRACE_DETACH still in progress.
- */
- if (sig) {
- engine->data = NULL;
- action = UTRACE_INTERRUPT;
- }
-
- ret = utrace_control(child, engine, action);
+ ret = utrace_control(child, engine, UTRACE_DETACH);
WARN_ON(ret && ret != -EINPROGRESS &&
ret != -ESRCH && ret != -EALREADY);
@@ -365,19 +352,6 @@ static u32 ptrace_resumed(struct task_st
return UTRACE_SIGNAL_REPORT | ptrace_report_vfork_done(task);
/*
- * If PTRACE_DETACH had a signal for us to deliver,
- * it didn't detach the engine, but marked it for us.
- */
- if (!engine->data) {
- read_lock(&tasklist_lock);
- if (task->ptrace & PT_PTRACED)
- engine->data = task->parent;
- else
- resume = UTRACE_DETACH;
- read_unlock(&tasklist_lock);
- }
-
- /*
* If we're stopping, or we haven't reported any signal,
* then we're all done for now.
*/
@@ -517,43 +491,18 @@ static struct utrace_engine *prepare_ptr
struct task_struct *child, struct task_struct *parent)
{
struct utrace_engine *engine;
-restart:
+
engine = utrace_attach_task(child, UTRACE_ATTACH_CREATE |
UTRACE_ATTACH_EXCLUSIVE |
UTRACE_ATTACH_MATCH_OPS,
&ptrace_utrace_ops, parent);
- if (engine == ERR_PTR(-EEXIST)) {
- /*
- * There is already some ptrace engine attached. Either
- * this attach will fail because another ptracer is
- * already attached, or else this engine was left behind
- * by PTRACE_DETACH to deliver a signal.
- */
- engine = utrace_attach_task(child,
- UTRACE_ATTACH_MATCH_OPS,
- &ptrace_utrace_ops, NULL);
- if (IS_ERR(engine)) {
- BUG_ON(PTR_ERR(engine) != -ENOENT);
- goto restart;
- }
- if (engine->data) {
- utrace_engine_put(engine);
- engine = ERR_PTR(-EEXIST);
- }
- }
+
if (IS_ERR(engine)) {
if (engine != ERR_PTR(-ESRCH) &&
engine != ERR_PTR(-ERESTARTNOINTR))
engine = ERR_PTR(-EPERM);
} else {
int ret = ptrace_update_utrace(child, engine);
- if (ret == -EINPROGRESS) {
- ret = utrace_barrier(child, engine);
- utrace_engine_put(engine);
- if (ret != -ERESTARTSYS)
- goto restart;
- return ERR_PTR(-ERESTARTNOINTR);
- }
if (ret)
engine = ERR_PTR(finish_ptrace_attach(child, engine,
-ESRCH));
