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, 12 insertions, 11 deletions

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 368a4d50cc30..043f833246a0 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -989,7 +989,7 @@ static ssize_t
 event_filter_read(struct file *filp, char __user *ubuf, size_t cnt,
                   loff_t *ppos)
 {
-        struct ftrace_event_call *call;
+        struct ftrace_event_file *file;
         struct trace_seq *s;
         int r = -ENODEV;
 
@@ -1004,12 +1004,12 @@ event_filter_read(struct file *filp, char __user *ubuf, size_t cnt,
         trace_seq_init(s);
 
         mutex_lock(&event_mutex);
-        call = event_file_data(filp);
-        if (call)
-                print_event_filter(call, s);
+        file = event_file_data(filp);
+        if (file)
+                print_event_filter(file, s);
         mutex_unlock(&event_mutex);
 
-        if (call)
+        if (file)
                 r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->len);
 
         kfree(s);
@@ -1021,7 +1021,7 @@ static ssize_t
 event_filter_write(struct file *filp, const char __user *ubuf, size_t cnt,
                    loff_t *ppos)
 {
-        struct ftrace_event_call *call;
+        struct ftrace_event_file *file;
         char *buf;
         int err = -ENODEV;
 
@@ -1039,9 +1039,9 @@ event_filter_write(struct file *filp, const char __user *ubuf, size_t cnt,
         buf[cnt] = '\0';
 
         mutex_lock(&event_mutex);
-        call = event_file_data(filp);
-        if (call)
-                err = apply_event_filter(call, buf);
+        file = event_file_data(filp);
+        if (file)
+                err = apply_event_filter(file, buf);
         mutex_unlock(&event_mutex);
 
         free_page((unsigned long) buf);
@@ -1539,7 +1539,7 @@ event_create_dir(struct dentry *parent, struct ftrace_event_file *file)
                         return -1;
                 }
         }
-        trace_create_file("filter", 0644, file->dir, call,
+        trace_create_file("filter", 0644, file->dir, file,
                           &ftrace_event_filter_fops);
 
         trace_create_file("format", 0444, file->dir, call,
@@ -1577,6 +1577,7 @@ static void event_remove(struct ftrace_event_call *call)
                 if (file->event_call != call)
                         continue;
                 ftrace_event_enable_disable(file, 0);
+                destroy_preds(file);
                 /*
                  * The do_for_each_event_file() is
                  * a double loop. After finding the call for this
@@ -1700,7 +1701,7 @@ static void __trace_remove_event_call(struct ftrace_event_call *call)
 {
         event_remove(call);
         trace_destroy_fields(call);
-        destroy_preds(call);
+        destroy_call_preds(call);
 }
 
 static int probe_remove_event_call(struct ftrace_event_call *call)