Merge tag 'trace-v6.3-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull tracing fixes from Steven Rostedt:

 - Fix timerlat notification, as it was not triggering the notify to
   users when a new max latency was hit.

 - Do not trigger max latency if the tracing is off.

   When tracing is off, the ring buffer is not updated, it does not make
   sense to notify when there's a new max latency detected by the
   tracer, as why that latency happened is not available. The tracing
   logic still runs when the ring buffer is disabled, but it should not
   be triggering notifications.

 - Fix race on freeing the synthetic event "last_cmd" variable by adding
   a mutex around it.

 - Fix race between reader and writer of the ring buffer by adding
   memory barriers. When the writer is still on the reader page it must
   have its content visible on the buffer before it moves the commit
   index that the reader uses to know how much content is on the page.

 - Make get_lock_parent_ip() always inlined, as it uses _THIS_IP_ and
   _RET_IP_, which gets broken if it is not inlined.

 - Make __field(int, arr[5]) in a TRACE_EVENT() macro fail to build.

   The field formats of trace events are calculated by using
   sizeof(type) and other means by what is passed into the structure
   macros like __field(). The __field() macro is only meant for atom
   types like int, long, short, pointer, etc. It is not meant for
   arrays.

   The code will currently compile with arrays, but then the format
   produced will be inaccurate, and user space parsing tools will break.

   Two bugs have already been fixed, now add code that will make the
   kernel fail to build if another trace event includes this buggy field
   format.

 - Fix boot up snapshot code:

   Boot snapshots were triggering when not even asked for on the kernel
   command line. This was caused by two bugs:

    1) It would trigger a snapshot on any instance if one was created
       from the kernel command line.

    2) The error handling would only affect the top level instance.
       So the fact that a snapshot was done on a instance that didn't
       allocate a buffer triggered a warning written into the top level
       buffer, and worse yet, disabled the top level buffer.

 - Fix memory leak that was caused when an error was logged in a trace
   buffer instance, and then the buffer instance was removed.

   The allocated error log messages still needed to be freed.

* tag 'trace-v6.3-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  tracing: Free error logs of tracing instances
  tracing: Fix ftrace_boot_snapshot command line logic
  tracing: Have tracing_snapshot_instance_cond() write errors to the appropriate instance
  tracing: Error if a trace event has an array for a __field()
  tracing/osnoise: Fix notify new tracing_max_latency
  tracing/timerlat: Notify new max thread latency
  ftrace: Mark get_lock_parent_ip() __always_inline
  ring-buffer: Fix race while reader and writer are on the same page
  tracing/synthetic: Fix races on freeing last_cmd

2 files changed, 18 insertions, 5 deletions

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 366c730beaa3..402fc061de75 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -980,7 +980,7 @@ static inline void __ftrace_enabled_restore(int enabled)
 #define CALLER_ADDR5 ((unsigned long)ftrace_return_address(5))
 #define CALLER_ADDR6 ((unsigned long)ftrace_return_address(6))
 
-static inline unsigned long get_lock_parent_ip(void)
+static __always_inline unsigned long get_lock_parent_ip(void)
 {
 	unsigned long addr = CALLER_ADDR0;
 
diff --git a/include/trace/stages/stage5_get_offsets.h b/include/trace/stages/stage5_get_offsets.h
index ac5c24d3beeb..e30a13be46ba 100644
--- a/include/trace/stages/stage5_get_offsets.h
+++ b/include/trace/stages/stage5_get_offsets.h
@@ -9,17 +9,30 @@
 #undef __entry
 #define __entry entry
 
+/*
+ * Fields should never declare an array: i.e. __field(int, arr[5])
+ * If they do, it will cause issues in parsing and possibly corrupt the
+ * events. To prevent that from happening, test the sizeof() a fictitious
+ * type called "struct _test_no_array_##item" which will fail if "item"
+ * contains array elements (like "arr[5]").
+ *
+ * If you hit this, use __array(int, arr, 5) instead.
+ */
 #undef __field
-#define __field(type, item)
+#define __field(type, item)					\
+	{ (void)sizeof(struct _test_no_array_##item *); }
 
 #undef __field_ext
-#define __field_ext(type, item, filter_type)
+#define __field_ext(type, item, filter_type)			\
+	{ (void)sizeof(struct _test_no_array_##item *); }
 
 #undef __field_struct
-#define __field_struct(type, item)
+#define __field_struct(type, item)				\
+	{ (void)sizeof(struct _test_no_array_##item *); }
 
 #undef __field_struct_ext
-#define __field_struct_ext(type, item, filter_type)
+#define __field_struct_ext(type, item, filter_type)		\
+	{ (void)sizeof(struct _test_no_array_##item *); }
 
 #undef __array
 #define __array(type, item, len)