The only patch which probably makes sense anyway.
Currently utrace assumes that task->utrace_flags can have only one
special bit, ENGINE_STOP. But it make sense to add more special bits.
For example, ptrace-utrace. It still uses task->ptrace for PT_PTRACE_CAP
and PT_UTRACED (the latter one is only needed to indicate that this task
is re-parented by ptrace). We can move them both into ->utrace_flags.
Introduce ENGINE_EXTRA_FLAGS == ENGINE_STOP and change utrace_set_events()
to use it. It is the only helper which changes target->utrace_flags and
engine->flags and needs the fix. utrace_reset() is OK, it just OR's all
engine->flags into task->utrace_flags.
See also the next "patches".
---
kernel/utrace.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
--- RHEL6/kernel/utrace.c~1_NONEVENT_BITS 2010-01-31 17:01:59.000000000
+0100
+++ RHEL6/kernel/utrace.c 2010-07-06 22:47:28.000000000 +0200
@@ -460,6 +460,8 @@ static void put_detached_list(struct lis
*/
#define ENGINE_STOP (1UL << _UTRACE_NEVENTS)
+#define ENGINE_EXTRA_FLAGS (ENGINE_STOP)
+
static void mark_engine_wants_stop(struct task_struct *task,
struct utrace_engine *engine)
{
@@ -530,14 +532,14 @@ int utrace_set_events(struct task_struct
* We just ignore the internal bit, so callers can use
* engine->flags to seed bitwise ops for our argument.
*/
- events &= ~ENGINE_STOP;
+ events &= ~ENGINE_EXTRA_FLAGS;
utrace = get_utrace_lock(target, engine, true);
if (unlikely(IS_ERR(utrace)))
return PTR_ERR(utrace);
old_utrace_flags = target->utrace_flags;
- old_flags = engine->flags & ~ENGINE_STOP;
+ old_flags = engine->flags & ~ENGINE_EXTRA_FLAGS;
if (target->exit_state &&
(((events & ~old_flags) & _UTRACE_DEATH_EVENTS) ||
@@ -569,7 +571,7 @@ int utrace_set_events(struct task_struct
read_unlock(&tasklist_lock);
}
- engine->flags = events | (engine->flags & ENGINE_STOP);
+ engine->flags = events | (engine->flags & ENGINE_EXTRA_FLAGS);
target->utrace_flags |= events;
if ((events & UTRACE_EVENT_SYSCALL) &&
