Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 21 Dec 2001 14:53:43 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 21 Dec 2001 14:53:33 -0500 Received: from wireless90.cs.wisc.edu ([128.105.48.190]:7057 "EHLO localhost.localdomain") by vger.kernel.org with ESMTP id ; Fri, 21 Dec 2001 14:53:18 -0500 To: marcelo@conectiva.com.br Cc: linux-kernel@vger.kernel.org, torvalds@transmeta.com, alan@lxorguk.ukuu.org.uk Subject: [PATCH] ptrace on stopped processes (2.4) From: vic Date: Fri, 21 Dec 2001 13:53:32 -0600 Message-ID: Lines: 47 User-Agent: Gnus/5.090004 (Oort Gnus v0.04) Emacs/20.7 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org This patch fixes a couple problems with ptrace's interaction with stopped processes on Linux 2.4. The most significant bug is that gdb cannot attach to a stopped process. Specifically, the wait that follows the PTRACE_ATTACH will block indefinitely. Another bug is that it is not possible to use PTRACE_DETACH to leave a process stopped, because ptrace ignores SIGSTOPs sent by the tracing process. This patch is against 2.4.16 on x86. I have tested gdb and strace. After this patch is reviewed, I would be happy to submit an analogous patch for the other platforms, although I cannot test it. Vic Zandy --- linux-2.4.16/arch/i386/kernel/signal.c Fri Sep 14 16:15:40 2001 +++ linux-2.4.16.1/arch/i386/kernel/signal.c Fri Dec 21 11:05:45 2001 @@ -620,9 +620,9 @@ continue; current->exit_code = 0; - /* The debugger continued. Ignore SIGSTOP. */ - if (signr == SIGSTOP) - continue; + /* The debugger continued. */ + if (signr == SIGSTOP && current->ptrace & PT_PTRACED) + continue; /* ignore SIGSTOP */ /* Update the siginfo structure. Is this good? */ if (signr != info.si_signo) { --- linux-2.4.16/kernel/ptrace.c Wed Nov 21 16:43:01 2001 +++ linux-2.4.16.1/kernel/ptrace.c Fri Dec 21 10:42:44 2001 @@ -89,8 +89,10 @@ SET_LINKS(task); } write_unlock_irq(&tasklist_lock); - - send_sig(SIGSTOP, task, 1); + if (task->state != TASK_STOPPED) + send_sig(SIGSTOP, task, 1); + else + task->exit_code = SIGSTOP; return 0; bad: - 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/