2007-11-18 16:48:32

by Oleg Nesterov

Subject: [PATCH] use __set_task_state() for TRACED/STOPPED tasks

1. It is much easier to grep for ->state change if __set_task_state() is used
instead of the direct assignment.

2. ptrace_stop() and handle_group_stop() use set_task_state() which adds the
unneeded mb() (btw even if we use mb() it is still possible that do_wait()
sees the new ->state but not ->exit_code, but this is ok).

Signed-off-by: Oleg Nesterov <[email protected]>

--- 24/kernel/fork.c~state 2007-11-09 12:57:31.000000000 +0300
+++ 24/kernel/fork.c 2007-11-18 19:27:38.000000000 +0300
@@ -1462,7 +1462,7 @@ long do_fork(unsigned long clone_flags,
if (!(clone_flags & CLONE_STOPPED))
wake_up_new_task(p, clone_flags);
else
- p->state = TASK_STOPPED;
+ __set_task_state(p, TASK_STOPPED);

if (unlikely (trace)) {
current->ptrace_message = nr;
--- 24/kernel/ptrace.c~state 2007-10-25 16:22:12.000000000 +0400
+++ 24/kernel/ptrace.c 2007-11-18 19:30:20.000000000 +0300
@@ -53,7 +53,7 @@ void ptrace_untrace(struct task_struct *
spin_lock(&child->sighand->siglock);
if (child->state == TASK_TRACED) {
if (child->signal->flags & SIGNAL_STOP_STOPPED) {
- child->state = TASK_STOPPED;
+ __set_task_state(child, TASK_STOPPED);
} else {
signal_wake_up(child, 1);
}
@@ -104,7 +104,7 @@ int ptrace_check_attach(struct task_stru
ret = 0;
spin_lock_irq(&child->sighand->siglock);
if (child->state == TASK_STOPPED) {
- child->state = TASK_TRACED;
+ __set_task_state(child, TASK_TRACED);
} else if (child->state != TASK_TRACED && !kill) {
ret = -ESRCH;
}
--- 24/kernel/signal.c~state 2007-11-09 12:57:31.000000000 +0300
+++ 24/kernel/signal.c 2007-11-18 19:33:19.000000000 +0300
@@ -1617,7 +1617,7 @@ static void ptrace_stop(int exit_code, i
current->exit_code = exit_code;

/* Let the debugger run. */
- set_current_state(TASK_TRACED);
+ __set_current_state(TASK_TRACED);
spin_unlock_irq(&current->sighand->siglock);
try_to_freeze();
read_lock(&tasklist_lock);
@@ -1781,7 +1781,7 @@ static int handle_group_stop(void)
if (stop_count == 0)
current->signal->flags = SIGNAL_STOP_STOPPED;
current->exit_code = current->signal->group_exit_code;
- set_current_state(TASK_STOPPED);
+ __set_current_state(TASK_STOPPED);
spin_unlock_irq(&current->sighand->siglock);
finish_stop(stop_count);
return 1;

2007-11-18 23:39:07

by Roland McGrath

Subject: Re: [PATCH] use __set_task_state() for TRACED/STOPPED tasks

Looks fine to me.


Thanks,
Roland