Messages in this thread Patch in this message | | | Date | Tue, 2 Jun 2009 22:39:39 +0200 | From | Oleg Nesterov <> | Subject | [PATCH for 2.6.30] ptrace: revert "ptrace_detach: the wrong wakeup breaks the ERESTARTxxx logic" |
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Commit 95a3540da9c81a5987be810e1d9a83640a366bd5 removed the "extra" wake_up_process() from ptrace_detach(), but as Jan pointed out this breaks the compatibility.
I believe the changelog is right and this wake_up() is wrong in many ways. But GDB assumes that ptrace(PTRACE_DETACH, child, 0, 0) always wakes up the tracee. Despite the fact this breaks SIGNAL_STOP_STOPPED/group_stop_count logic, and despite the fact this wake_up_process() can break another assumption: PTRACE_DETACH with SIGSTOP should leave the tracee in TASK_STOPPED case. Because the untraced child can dequeue SIGSTOP and call do_signal_stop() before ptrace_detach() calls wake_up_process().
Revert this change for now. We need some fixes even if we we want to keep the current behaviour, but these fixes are not for 2.6.30.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
--- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -304,6 +304,8 @@ int ptrace_detach(struct task_struct *ch if (child->ptrace) { child->exit_code = data; dead = __ptrace_detach(current, child); + if (!child->exit_state) + wake_up_process(child); } write_unlock_irq(&tasklist_lock);
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