Change ptrace_attach_task() to re-use the self-detaching engine first,
then do utrace_attach_task(UTRACE_ATTACH_CREATE).
Todo:
- re-check this all (and test)
- rename check()
- cleanups the mess in ptrace_attach_task()
- ptrace_detach_task() should clear options/flags, if we re-use
this engine then ptrace_attach_task()->utrace_set_events()
happens a bit late.
---
kernel/ptrace.c | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)
--- PU/kernel/ptrace.c~78_REUSE_PARTING_ENGINE 2009-10-09 18:51:56.000000000
+0200
+++ PU/kernel/ptrace.c 2009-10-09 19:04:34.000000000 +0200
@@ -431,6 +431,15 @@ static inline int __ptrace_set_options(s
return utrace_set_events(target, engine, events);
}
+static bool check(void *data)
+{
+ struct ptrace_context *context = data;
+ if (context->resume != UTRACE_DETACH)
+ return false;
+ context->resume = UTRACE_RESUME;
+ return true;
+}
+
/*
* Attach a utrace engine for ptrace and set up its event mask.
* Returns error code or 0 on success.
@@ -441,6 +450,20 @@ static int ptrace_attach_task(struct tas
struct utrace_engine *engine;
int err;
+ engine = utrace_attach_task(tracee, UTRACE_ATTACH_MATCH_OPS |
+ UTRACE_ATTACH_MATCH_CHECK,
+ &ptrace_utrace_ops, check);
+ if (!IS_ERR(engine)) {
+ /*
+ * Make sure we don't race with ptrace_report_signal()
+ */
+ utrace_barrier(tracee, engine);
+ if (engine->ops != &ptrace_utrace_ops)
+ utrace_engine_put(engine);
+ else
+ goto finish;
+ }
+
context = kzalloc(sizeof(*context), GFP_KERNEL);
if (unlikely(!context))
return -ENOMEM;
@@ -458,6 +481,7 @@ static int ptrace_attach_task(struct tas
kfree(context);
return err;
}
+finish:
/*
* It can fail only if the tracee is dead, the caller
* must notice this before setting PT_PTRACED.
