Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753620Ab1F2CNp (ORCPT ); Tue, 28 Jun 2011 22:13:45 -0400 Received: from mail-fx0-f52.google.com ([209.85.161.52]:51384 "EHLO mail-fx0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750974Ab1F2CNm (ORCPT ); Tue, 28 Jun 2011 22:13:42 -0400 From: Denys Vlasenko To: Oleg Nesterov , Tejun Heo Subject: [PATCHv4] ptrace: make former thread ID available via PTRACE_GETEVENTMSG after PTRACE_EVENT_EXEC stop Date: Wed, 29 Jun 2011 04:13:39 +0200 User-Agent: KMail/1.8.2 Cc: linux-kernel@vger.kernel.org MIME-Version: 1.0 Content-Disposition: inline Message-Id: <201106290413.39429.vda.linux@googlemail.com> Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2060 Lines: 66 Hi Oleg, Please take a look at version 4 of this patch. When multithreaded program execs under ptrace, all traced threads report WIFEXITED status, except for thread group leader and the thread which execs. Unless tracer tracks thread group relationship between tracees, which is a nontrivial task, it will not detect that execed thread no longer exists. This patch allows tracer to figure out which thread performed this exec, by requesting PTRACE_GETEVENTMSG in PTRACE_EVENT_EXEC stop. Another, samller problem which is solved by this patch is that tracer now can figure out which of the several concurrent execs in multithreaded program succeeded. Signed-off-by: Denys Vlasenko -- vda diff --git a/fs/exec.c b/fs/exec.c index 8dca45b..55819be 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1357,6 +1357,7 @@ int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs) unsigned int depth = bprm->recursion_depth; int try,retval; struct linux_binfmt *fmt; + pid_t old_pid; retval = security_bprm_check(bprm); if (retval) @@ -1370,6 +1371,11 @@ int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs) if (retval) return retval; + /* Need to fetch pid before load_binary changes it */ + rcu_read_lock(); + old_pid = task_pid_nr_ns(current, task_active_pid_ns(current->parent)); + rcu_read_unlock(); + retval = -ENOENT; for (try=0; try<2; try++) { read_lock(&binfmt_lock); @@ -1389,7 +1395,8 @@ int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs) bprm->recursion_depth = depth; if (retval >= 0) { if (depth == 0) - ptrace_event(PTRACE_EVENT_EXEC, 0); + ptrace_event(PTRACE_EVENT_EXEC, + old_pid); put_binfmt(fmt); allow_write_access(bprm->file); if (bprm->file) -- 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/