From edaba2c5334492f82d39ec35637c6dea5176a977 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Thu, 4 Jun 2009 16:29:09 -0700 Subject: [PATCH] ptrace: revert "ptrace_detach: the wrong wakeup breaks the ERESTARTxxx logic" Commit 95a3540da9c81a5987be810e1d9a83640a366bd5 ("ptrace_detach: the wrong wakeup breaks the ERESTARTxxx logic") 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 Acked-by: Roland McGrath Cc: Jan Kratochvil Cc: Denys Vlasenko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/ptrace.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 0692ab5a0d67..42c317874cfa 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -304,6 +304,8 @@ int ptrace_detach(struct task_struct *child, unsigned int data) 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); -- 2.20.1