tracing: Update event filters for multibuffer

The trace event filters are still tied to event calls rather than
event files, which means you don't get what you'd expect when using
filters in the multibuffer case:

Before:

  # echo 'bytes_alloc > 8192' > /sys/kernel/debug/tracing/events/kmem/kmalloc/filter
  # cat /sys/kernel/debug/tracing/events/kmem/kmalloc/filter
  bytes_alloc > 8192
  # mkdir /sys/kernel/debug/tracing/instances/test1
  # echo 'bytes_alloc > 2048' > /sys/kernel/debug/tracing/instances/test1/events/kmem/kmalloc/filter
  # cat /sys/kernel/debug/tracing/events/kmem/kmalloc/filter
  bytes_alloc > 2048
  # cat /sys/kernel/debug/tracing/instances/test1/events/kmem/kmalloc/filter
  bytes_alloc > 2048

Setting the filter in tracing/instances/test1/events shouldn't affect
the same event in tracing/events as it does above.

After:

  # echo 'bytes_alloc > 8192' > /sys/kernel/debug/tracing/events/kmem/kmalloc/filter
  # cat /sys/kernel/debug/tracing/events/kmem/kmalloc/filter
  bytes_alloc > 8192
  # mkdir /sys/kernel/debug/tracing/instances/test1
  # echo 'bytes_alloc > 2048' > /sys/kernel/debug/tracing/instances/test1/events/kmem/kmalloc/filter
  # cat /sys/kernel/debug/tracing/events/kmem/kmalloc/filter
  bytes_alloc > 8192
  # cat /sys/kernel/debug/tracing/instances/test1/events/kmem/kmalloc/filter
  bytes_alloc > 2048

We'd like to just move the filter directly from ftrace_event_call to
ftrace_event_file, but there are a couple cases that don't yet have
multibuffer support and therefore have to continue using the current
event_call-based filters.  For those cases, a new USE_CALL_FILTER bit
is added to the event_call flags, whose main purpose is to keep the
old behavior for those cases until they can be updated with
multibuffer support; at that point, the USE_CALL_FILTER flag (and the
new associated call_filter_check_discard() function) can go away.

The multibuffer support also made filter_current_check_discard()
redundant, so this change removes that function as well and replaces
it with filter_check_discard() (or call_filter_check_discard() as
appropriate).

Link: http://lkml.kernel.org/r/f16e9ce4270c62f46b2e966119225e1c3cca7e60.1382620672.git.tom.zanussi@linux.intel.com

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 30 insertions, 10 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 063a92bad578..489da8b19f30 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -235,13 +235,33 @@ void trace_array_put(struct trace_array *this_tr)
         mutex_unlock(&trace_types_lock);
 }
 
-int filter_current_check_discard(struct ring_buffer *buffer,
-                                 struct ftrace_event_call *call, void *rec,
-                                 struct ring_buffer_event *event)
+int filter_check_discard(struct ftrace_event_file *file, void *rec,
+                         struct ring_buffer *buffer,
+                         struct ring_buffer_event *event)
 {
-        return filter_check_discard(call, rec, buffer, event);
+        if (unlikely(file->flags & FTRACE_EVENT_FL_FILTERED) &&
+            !filter_match_preds(file->filter, rec)) {
+                ring_buffer_discard_commit(buffer, event);
+                return 1;
+        }
+
+        return 0;
+}
+EXPORT_SYMBOL_GPL(filter_check_discard);
+
+int call_filter_check_discard(struct ftrace_event_call *call, void *rec,
+                              struct ring_buffer *buffer,
+                              struct ring_buffer_event *event)
+{
+        if (unlikely(call->flags & TRACE_EVENT_FL_FILTERED) &&
+            !filter_match_preds(call->filter, rec)) {
+                ring_buffer_discard_commit(buffer, event);
+                return 1;
+        }
+
+        return 0;
 }
-EXPORT_SYMBOL_GPL(filter_current_check_discard);
+EXPORT_SYMBOL_GPL(call_filter_check_discard);
 
 cycle_t buffer_ftrace_now(struct trace_buffer *buf, int cpu)
 {
@@ -1633,7 +1653,7 @@ trace_function(struct trace_array *tr,
         entry->ip                       = ip;
         entry->parent_ip                = parent_ip;
 
-        if (!filter_check_discard(call, entry, buffer, event))
+        if (!call_filter_check_discard(call, entry, buffer, event))
                 __buffer_unlock_commit(buffer, event);
 }
 
@@ -1717,7 +1737,7 @@ static void __ftrace_trace_stack(struct ring_buffer *buffer,
 
         entry->size = trace.nr_entries;
 
-        if (!filter_check_discard(call, entry, buffer, event))
+        if (!call_filter_check_discard(call, entry, buffer, event))
                 __buffer_unlock_commit(buffer, event);
 
  out:
@@ -1819,7 +1839,7 @@ ftrace_trace_userstack(struct ring_buffer *buffer, unsigned long flags, int pc)
         trace.entries           = entry->caller;
 
         save_stack_trace_user(&trace);
-        if (!filter_check_discard(call, entry, buffer, event))
+        if (!call_filter_check_discard(call, entry, buffer, event))
                 __buffer_unlock_commit(buffer, event);
 
  out_drop_count:
@@ -2011,7 +2031,7 @@ int trace_vbprintk(unsigned long ip, const char *fmt, va_list args)
         entry->fmt                      = fmt;
 
         memcpy(entry->buf, tbuffer, sizeof(u32) * len);
-        if (!filter_check_discard(call, entry, buffer, event)) {
+        if (!call_filter_check_discard(call, entry, buffer, event)) {
                 __buffer_unlock_commit(buffer, event);
                 ftrace_trace_stack(buffer, flags, 6, pc);
         }
@@ -2066,7 +2086,7 @@ __trace_array_vprintk(struct ring_buffer *buffer,
 
         memcpy(&entry->buf, tbuffer, len);
         entry->buf[len] = '\0';
-        if (!filter_check_discard(call, entry, buffer, event)) {
+        if (!call_filter_check_discard(call, entry, buffer, event)) {
                 __buffer_unlock_commit(buffer, event);
                 ftrace_trace_stack(buffer, flags, 6, pc);
         }