Merge tag 'trace-v5.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing fixes from Steven Rostedt:
 "Functional fixes:

   - Fix big endian conversion for arm64 in recordmcount processing

   - Fix timestamp corruption in ring buffer on discarding events

   - Fix memory leak in __create_synth_event()

   - Skip selftests if tracing is disabled as it will cause them to
     fail.

  Non-functional fixes:

   - Fix help text in Kconfig

   - Remove duplicate prototype for trace_empty()

   - Fix stale comment about the trace_event_call flags.

  Self test update:

   - Add more information to the validation output of when a corrupt
     timestamp is found in the ring buffer, and also trigger a warning
     to make sure that tests catch it"

* tag 'trace-v5.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Fix comment about the trace_event_call flags
  tracing: Skip selftests if tracing is disabled
  tracing: Fix memory leak in __create_synth_event()
  ring-buffer: Add a little more information and a WARN when time stamp going backwards is detected
  ring-buffer: Force before_stamp and write_stamp to be different on discard
  tracing: Fix help text of TRACEPOINT_BENCHMARK in Kconfig
  tracing: Remove duplicate declaration from trace.h
  ftrace: Have recordmcount use w8 to read relp->r_info in arm64_is_fake_mcount

1 files changed, 18 insertions, 3 deletions

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index b9dad3500041..68744c51517e 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -2815,6 +2815,17 @@ rb_try_to_discard(struct ring_buffer_per_cpu *cpu_buffer,
 			return 0;
 
 		/*
+		 * It's possible that the event time delta is zero
+		 * (has the same time stamp as the previous event)
+		 * in which case write_stamp and before_stamp could
+		 * be the same. In such a case, force before_stamp
+		 * to be different than write_stamp. It doesn't
+		 * matter what it is, as long as its different.
+		 */
+		if (!delta)
+			rb_time_set(&cpu_buffer->before_stamp, 0);
+
+		/*
 		 * If an event were to come in now, it would see that the
 		 * write_stamp and the before_stamp are different, and assume
 		 * that this event just added itself before updating
@@ -3307,9 +3318,13 @@ static void check_buffer(struct ring_buffer_per_cpu *cpu_buffer,
 			goto out;
 		}
 		atomic_inc(&cpu_buffer->record_disabled);
-		pr_warn("[CPU: %d]TIME DOES NOT MATCH expected:%lld actual:%lld delta:%lld after:%lld\n",
-		       cpu_buffer->cpu,
-		       ts + info->delta, info->ts, info->delta, info->after);
+		/* There's some cases in boot up that this can happen */
+		WARN_ON_ONCE(system_state != SYSTEM_BOOTING);
+		pr_warn("[CPU: %d]TIME DOES NOT MATCH expected:%lld actual:%lld delta:%lld before:%lld after:%lld%s\n",
+			cpu_buffer->cpu,
+			ts + info->delta, info->ts, info->delta,
+			info->before, info->after,
+			full ? " (full)" : "");
 		dump_buffer_page(bpage, info, tail);
 		atomic_dec(&ts_dump);
 		/* Do not re-enable checking */