From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965259Ab1KJDkl (ORCPT ); Wed, 9 Nov 2011 22:40:41 -0500 Received: from cantor2.suse.de ([195.135.220.15]:44190 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757086Ab1KJDke (ORCPT ); Wed, 9 Nov 2011 22:40:34 -0500 X-Mailbox-Line: From gregkh@clark.kroah.org Wed Nov 9 13:31:53 2011 Message-Id: <20111109213153.097904561@clark.kroah.org> User-Agent: quilt/0.48-16.4 Date: Wed, 09 Nov 2011 13:32:36 -0800 From: Greg KH To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Masami Hiramatsu , Arnaldo Carvalho de Melo , Ingo Molnar , Frederic Weisbecker , "Frank Ch. Eigler" , Steven Rostedt Subject: [109/264] ftrace/kprobes: Fix not to delete probes if in use In-Reply-To: <20111109213508.GA3476@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Masami Hiramatsu commit 02ca1521ad404cf566e0075848f80d064c0a0503 upstream. Fix kprobe-tracer not to delete a probe if the probe is in use. In that case, delete operation will return -EBUSY. This bug can cause a kernel panic if enabled probes are deleted during perf record. (Add some probes on functions) sh-4.2# perf probe --del probe:\* sh-4.2# exit (kernel panic) This is originally reported on the fedora bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=742383 I've also checked that this problem doesn't happen on tracepoints when module removing because perf event locks target module. $ sudo ./perf record -e xfs:\* -aR sh sh-4.2# rmmod xfs ERROR: Module xfs is in use sh-4.2# exit [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.203 MB perf.data (~8862 samples) ] Signed-off-by: Masami Hiramatsu Cc: Arnaldo Carvalho de Melo Cc: Ingo Molnar Cc: Frederic Weisbecker Cc: Frank Ch. Eigler Link: http://lkml.kernel.org/r/20111004104438.14591.6553.stgit@fedora15 Signed-off-by: Steven Rostedt Signed-off-by: Greg Kroah-Hartman --- kernel/trace/trace_kprobe.c | 58 +++++++++++++++++++++++++++++++++++++------- 1 file changed, 49 insertions(+), 9 deletions(-) --- a/kernel/trace/trace_kprobe.c +++ b/kernel/trace/trace_kprobe.c @@ -836,11 +836,17 @@ static void __unregister_trace_probe(str } /* Unregister a trace_probe and probe_event: call with locking probe_lock */ -static void unregister_trace_probe(struct trace_probe *tp) +static int unregister_trace_probe(struct trace_probe *tp) { + /* Enabled event can not be unregistered */ + if (trace_probe_is_enabled(tp)) + return -EBUSY; + __unregister_trace_probe(tp); list_del(&tp->list); unregister_probe_event(tp); + + return 0; } /* Register a trace_probe and probe_event */ @@ -854,7 +860,9 @@ static int register_trace_probe(struct t /* Delete old (same name) event if exist */ old_tp = find_trace_probe(tp->call.name, tp->call.class->system); if (old_tp) { - unregister_trace_probe(old_tp); + ret = unregister_trace_probe(old_tp); + if (ret < 0) + goto end; free_trace_probe(old_tp); } @@ -892,6 +900,7 @@ static int trace_probe_module_callback(s mutex_lock(&probe_lock); list_for_each_entry(tp, &probe_list, list) { if (trace_probe_within_module(tp, mod)) { + /* Don't need to check busy - this should have gone. */ __unregister_trace_probe(tp); ret = __register_trace_probe(tp); if (ret) @@ -1205,10 +1214,11 @@ static int create_trace_probe(int argc, return -ENOENT; } /* delete an event */ - unregister_trace_probe(tp); - free_trace_probe(tp); + ret = unregister_trace_probe(tp); + if (ret == 0) + free_trace_probe(tp); mutex_unlock(&probe_lock); - return 0; + return ret; } if (argc < 2) { @@ -1317,18 +1327,29 @@ error: return ret; } -static void release_all_trace_probes(void) +static int release_all_trace_probes(void) { struct trace_probe *tp; + int ret = 0; mutex_lock(&probe_lock); + /* Ensure no probe is in use. */ + list_for_each_entry(tp, &probe_list, list) + if (trace_probe_is_enabled(tp)) { + ret = -EBUSY; + goto end; + } /* TODO: Use batch unregistration */ while (!list_empty(&probe_list)) { tp = list_entry(probe_list.next, struct trace_probe, list); unregister_trace_probe(tp); free_trace_probe(tp); } + +end: mutex_unlock(&probe_lock); + + return ret; } /* Probes listing interfaces */ @@ -1380,9 +1401,13 @@ static const struct seq_operations probe static int probes_open(struct inode *inode, struct file *file) { - if ((file->f_mode & FMODE_WRITE) && - (file->f_flags & O_TRUNC)) - release_all_trace_probes(); + int ret; + + if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) { + ret = release_all_trace_probes(); + if (ret < 0) + return ret; + } return seq_open(file, &probes_seq_op); } @@ -2055,6 +2080,21 @@ static __init int kprobe_trace_self_test ret = target(1, 2, 3, 4, 5, 6); + /* Disable trace points before removing it */ + tp = find_trace_probe("testprobe", KPROBE_EVENT_SYSTEM); + if (WARN_ON_ONCE(tp == NULL)) { + pr_warning("error on getting test probe.\n"); + warn++; + } else + disable_trace_probe(tp, TP_FLAG_TRACE); + + tp = find_trace_probe("testprobe2", KPROBE_EVENT_SYSTEM); + if (WARN_ON_ONCE(tp == NULL)) { + pr_warning("error on getting 2nd test probe.\n"); + warn++; + } else + disable_trace_probe(tp, TP_FLAG_TRACE); + ret = command_trace_probe("-:testprobe"); if (WARN_ON_ONCE(ret)) { pr_warning("error on deleting a probe.\n");