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While writing selftests for a new feature, I triggered two existing 

bugs that deal with triggers and instances.
 
  The first is a generic trigger bug where the triggers are not removed
  from a link list properly when deleting an instance.
 
  The second is specific to snapshots, where the snapshot is does the
  snapshot to the top level buffer, when it is suppose to snapshot the
  buffer associated to the instance the snapshot trigger exists in.
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Merge tag 'trace-v4.17-rc4-3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing fixes from Steven Rostedt:
 "While writing selftests for a new feature, I triggered two existing
  bugs that deal with triggers and instances.

   - a generic trigger bug where the triggers are not removed from a
     linked list properly when deleting an instance.

   - a bug specific to snapshots, where the snapshot is done in the top
     level buffer, when it is supposed to snapshot the buffer associated
     to the instance the snapshot trigger exists in"

* tag 'trace-v4.17-rc4-3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Make the snapshot trigger work with instances
  tracing: Fix crash when freeing instances with event triggers
This commit is contained in:
Linus Torvalds 2018-05-29 07:28:48 -05:00
parent 786b71f5b7 2824f50332
commit 3d661e2a2d
3 changed files with 28 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
kernel/trace/trace.c
View File

@ -893,7 +893,7 @@ int __trace_bputs(unsigned long ip, const char *str)
EXPORT_SYMBOL_GPL(__trace_bputs);
#ifdef CONFIG_TRACER_SNAPSHOT
static void tracing_snapshot_instance(struct trace_array *tr)
void tracing_snapshot_instance(struct trace_array *tr)
{
struct tracer *tracer = tr->current_trace;
unsigned long flags;
@ -949,7 +949,7 @@ static int resize_buffer_duplicate_size(struct trace_buffer *trace_buf,
struct trace_buffer *size_buf, int cpu_id);
static void set_buffer_entries(struct trace_buffer *buf, unsigned long val);
static int alloc_snapshot(struct trace_array *tr)
int tracing_alloc_snapshot_instance(struct trace_array *tr)
{
int ret;
@ -995,7 +995,7 @@ int tracing_alloc_snapshot(void)
struct trace_array *tr = &global_trace;
int ret;
ret = alloc_snapshot(tr);
ret = tracing_alloc_snapshot_instance(tr);
WARN_ON(ret < 0);
return ret;
@ -5408,7 +5408,7 @@ static int tracing_set_tracer(struct trace_array *tr, const char *buf)
#ifdef CONFIG_TRACER_MAX_TRACE
if (t->use_max_tr && !had_max_tr) {
ret = alloc_snapshot(tr);
ret = tracing_alloc_snapshot_instance(tr);
if (ret < 0)
goto out;
}
@ -6451,7 +6451,7 @@ tracing_snapshot_write(struct file *filp, const char __user *ubuf, size_t cnt,
}
#endif
if (!tr->allocated_snapshot) {
ret = alloc_snapshot(tr);
ret = tracing_alloc_snapshot_instance(tr);
if (ret < 0)
break;
}
@ -7179,7 +7179,7 @@ ftrace_trace_snapshot_callback(struct trace_array *tr, struct ftrace_hash *hash,
return ret;
out_reg:
ret = alloc_snapshot(tr);
ret = tracing_alloc_snapshot_instance(tr);
if (ret < 0)
goto out;

11
kernel/trace/trace.h
View File

@ -1817,6 +1817,17 @@ static inline void __init trace_event_init(void) { }
static inline void trace_event_eval_update(struct trace_eval_map **map, int len) { }
#endif
#ifdef CONFIG_TRACER_SNAPSHOT
void tracing_snapshot_instance(struct trace_array *tr);
int tracing_alloc_snapshot_instance(struct trace_array *tr);
#else
static inline void tracing_snapshot_instance(struct trace_array *tr) { }
static inline int tracing_alloc_snapshot_instance(struct trace_array *tr)
{
return 0;
}
#endif
extern struct trace_iterator *tracepoint_print_iter;
#endif /* _LINUX_KERNEL_TRACE_H */

15
kernel/trace/trace_events_trigger.c
View File

@ -483,9 +483,10 @@ clear_event_triggers(struct trace_array *tr)
struct trace_event_file *file;
list_for_each_entry(file, &tr->events, list) {
struct event_trigger_data *data;
list_for_each_entry_rcu(data, &file->triggers, list) {
struct event_trigger_data *data, *n;
list_for_each_entry_safe(data, n, &file->triggers, list) {
trace_event_trigger_enable_disable(file, 0);
list_del_rcu(&data->list);
if (data->ops->free)
data->ops->free(data->ops, data);
}
@ -642,6 +643,7 @@ event_trigger_callback(struct event_command *cmd_ops,
trigger_data->count = -1;
trigger_data->ops = trigger_ops;
trigger_data->cmd_ops = cmd_ops;
trigger_data->private_data = file;
INIT_LIST_HEAD(&trigger_data->list);
INIT_LIST_HEAD(&trigger_data->named_list);
@ -1053,7 +1055,12 @@ static void
snapshot_trigger(struct event_trigger_data *data, void *rec,
struct ring_buffer_event *event)
{
tracing_snapshot();
struct trace_event_file *file = data->private_data;
if (file)
tracing_snapshot_instance(file->tr);
else
tracing_snapshot();
}
static void
@ -1076,7 +1083,7 @@ register_snapshot_trigger(char *glob, struct event_trigger_ops *ops,
{
int ret = register_trigger(glob, ops, data, file);
if (ret > 0 && tracing_alloc_snapshot() != 0) {
if (ret > 0 && tracing_alloc_snapshot_instance(file->tr) != 0) {
unregister_trigger(glob, ops, data, file);
ret = 0;
}