From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 23701 invoked by alias); 25 May 2006 18:11:10 -0000 Received: (qmail 23692 invoked by uid 22791); 25 May 2006 18:11:09 -0000 X-Spam-Status: No, hits=-3.1 required=5.0 tests=AWL,BAYES_00,SPF_HELO_PASS,SPF_PASS X-Spam-Check-By: sourceware.org Received: from mx1.redhat.com (HELO mx1.redhat.com) (66.187.233.31) by sourceware.org (qpsmtpd/0.31) with ESMTP; Thu, 25 May 2006 18:11:07 +0000 Received: from int-mx1.corp.redhat.com (int-mx1.corp.redhat.com [172.16.52.254]) by mx1.redhat.com (8.12.11.20060308/8.12.11) with ESMTP id k4PIB5k8030450 for ; Thu, 25 May 2006 14:11:05 -0400 Received: from pobox.corp.redhat.com (pobox.corp.redhat.com [172.16.52.156]) by int-mx1.corp.redhat.com (8.12.11.20060308/8.12.11) with ESMTP id k4PIB5vA018428 for ; Thu, 25 May 2006 14:11:05 -0400 Received: from vpn83-138.boston.redhat.com (vpn83-138.boston.redhat.com [172.16.83.138]) by pobox.corp.redhat.com (8.12.8/8.12.8) with ESMTP id k4PIB4Lw007208 for ; Thu, 25 May 2006 14:11:04 -0400 Subject: how to handle userspace string copy failures From: Martin Hunt To: systemtap@sources.redhat.com Content-Type: text/plain Organization: Red Hat Inc. Date: Thu, 25 May 2006 18:11:00 -0000 Message-Id: <1148580663.6909.12.camel@dragon> Mime-Version: 1.0 X-Mailer: Evolution 2.6.1 (2.6.1-1.fc5.2) Content-Transfer-Encoding: 7bit X-IsSubscribed: yes Mailing-List: contact systemtap-help@sourceware.org; run by ezmlm Precedence: bulk List-Subscribe: List-Post: List-Help: , Sender: systemtap-owner@sourceware.org X-SW-Source: 2006-q2/txt/msg00493.txt.bz2 With the recent change in page fault handling, we are seeing more failures from user_string(). Unfortunately, that results in an error being logged and the script terminating. This is partly my fault because I fixed this once before and then changed it back when asked to, forgetting why this was bad. So, for the record, we cannot guarantee always being able to always access userspace and such failures should not terminate the script. At worst, I think we should print warnings. I also propose that any user_string() request that fails should return "". If there are no objections, I will check in this tapset change. Martin