Messages in this thread |  | | Date | Sun, 1 Sep 2002 15:33:13 -0400 | From | Daniel Jacobowitz <> | Subject | Re: [PATCH] remove BUG_ON(p->ptrace) in release_task() |
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On Mon, Sep 02, 2002 at 02:38:03AM +0900, OGAWA Hirofumi wrote: > Hi, > > I think, BUG_ON(p->ptrace) will be called if the CLONE_DETACH process > is traced. This patch removes BUG_ON(p->ptrace), and also removes > BUG_ON(p->ptrace) workaround in sys_wait4().
The BUG_ON is correct, and that isn't a workaround - if the list is not empty, then it will be garbage after the task struct is freed. Your patch breaks tracing of normal processes again, because the ptrace_list will not be empty.
It may be that the BUG_ON can be triggered for detached processes. In that case a ptrace_unlink is necessary somewhere else.
> > Please apply. > -- > OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> > > --- linux-2.5.33/kernel/exit.c~ 2002-09-02 01:02:07.000000000 +0900 > +++ linux-2.5.33/kernel/exit.c 2002-09-02 00:54:47.000000000 +0900 > @@ -66,8 +66,7 @@ > atomic_dec(&p->user->processes); > security_ops->task_free_security(p); > free_uid(p->user); > - BUG_ON(p->ptrace || !list_empty(&p->ptrace_list) || > - !list_empty(&p->ptrace_children)); > + BUG_ON(!list_empty(&p->ptrace_list)||!list_empty(&p->ptrace_children)); > unhash_process(p); > > release_thread(p); > @@ -717,14 +716,8 @@ > ptrace_unlink(p); > do_notify_parent(p, SIGCHLD); > write_unlock_irq(&tasklist_lock); > - } else { > - if (p->ptrace) { > - write_lock_irq(&tasklist_lock); > - ptrace_unlink(p); > - write_unlock_irq(&tasklist_lock); > - } > + } else > release_task(p); > - } > goto end_wait4; > default: > continue; > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ >
-- Daniel Jacobowitz MontaVista Software Debian GNU/Linux Developer - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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