ftrace/kprobes: Fix not to delete probes if in use
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 <masami.hiramatsu.pt@hitachi.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Frank Ch. Eigler <fche@redhat.com> Cc: stable@kernel.org Link: http://lkml.kernel.org/r/20111004104438.14591.6553.stgit@fedora15 Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
parent
9d3ec7a0c4
commit
02ca1521ad
|
@ -836,11 +836,17 @@ static void __unregister_trace_probe(struct trace_probe *tp)
|
|||
}
|
||||
|
||||
/* 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 trace_probe *tp)
|
|||
/* 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(struct notifier_block *nb,
|
|||
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, char **argv)
|
|||
return -ENOENT;
|
||||
}
|
||||
/* delete an event */
|
||||
unregister_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 probes_seq_op = {
|
|||
|
||||
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_tests_init(void)
|
|||
|
||||
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");
|
||||
|
|
Loading…
Reference in a new issue