Merge tag 'trace-v6.5-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull tracing fixes from Steven Rostedt:

 - Fix ring buffer being permanently disabled due to missed
   record_disabled()

   Changing the trace cpu mask will disable the ring buffers for the
   CPUs no longer in the mask. But it fails to update the snapshot
   buffer. If a snapshot takes place, the accounting for the ring buffer
   being disabled is corrupted and this can lead to the ring buffer
   being permanently disabled.

 - Add test case for snapshot and cpu mask working together

 - Fix memleak by the function graph tracer not getting closed properly.

   The iterator is used to read the ring buffer. When it opens, it calls
   the open function of a tracer, and when it is closed, it calls the
   close iteration. While a trace is being read, it is still possible to
   change the tracer.

   If this happens between the function graph tracer and the wakeup
   tracer (which uses function graph tracing), the tracers are not
   closed properly during when the iterator sees the switch, and the
   wakeup function did not initialize its private pointer to NULL, which
   is used to know if the function graph tracer was the last tracer. It
   could be fooled in thinking it is, but then on exit it does not call
   the close function of the function graph tracer to clean up its data.

 - Fix synthetic events on big endian machines, by introducing a union
   that does the conversions properly.

 - Fix synthetic events from printing out the number of elements in the
   stacktrace when it shouldn't.

 - Fix synthetic events stacktrace to not print a bogus value at the
   end.

 - Introduce a pipe_cpumask that prevents the trace_pipe files from
   being opened by more than one task (file descriptor).

   There was a race found where if splice is called, the iter->ent could
   become stale and events could be missed. There's no point reading a
   producer/consumer file by more than one task as they will corrupt
   each other anyway. Add a cpumask that keeps track of the per_cpu
   trace_pipe files as well as the global trace_pipe file that prevents
   more than one open of a trace_pipe file that represents the same ring
   buffer. This prevents the race from happening.

 - Fix ftrace samples for arm64 to work with older compilers.

* tag 'trace-v6.5-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  samples: ftrace: Replace bti assembly with hint for older compiler
  tracing: Introduce pipe_cpumask to avoid race on trace_pipes
  tracing: Fix memleak due to race between current_tracer and trace
  tracing/synthetic: Allocate one additional element for size
  tracing/synthetic: Skip first entry for stack traces
  tracing/synthetic: Use union instead of casts
  selftests/ftrace: Add a basic testcase for snapshot
  tracing: Fix cpu buffers unavailable due to 'record_disabled' missed

1 files changed, 31 insertions, 0 deletions

diff --git a/tools/testing/selftests/ftrace/test.d/00basic/snapshot1.tc b/tools/testing/selftests/ftrace/test.d/00basic/snapshot1.tc
new file mode 100644
index 000000000000..63b76cf2a360
--- /dev/null
+++ b/tools/testing/selftests/ftrace/test.d/00basic/snapshot1.tc
@@ -0,0 +1,31 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# description: Snapshot and tracing_cpumask
+# requires: trace_marker tracing_cpumask snapshot
+# flags: instance
+
+# This testcase is constrived to reproduce a problem that the cpu buffers
+# become unavailable which is due to 'record_disabled' of array_buffer and
+# max_buffer being messed up.
+
+# Store origin cpumask
+ORIG_CPUMASK=`cat tracing_cpumask`
+
+# Stop tracing all cpu
+echo 0 > tracing_cpumask
+
+# Take a snapshot of the main buffer
+echo 1 > snapshot
+
+# Restore origin cpumask, note that there should be some cpus being traced
+echo ${ORIG_CPUMASK} > tracing_cpumask
+
+# Set tracing on
+echo 1 > tracing_on
+
+# Write a log into buffer
+echo "test input 1" > trace_marker
+
+# Ensure the log writed so that cpu buffers are still available
+grep -q "test input 1" trace
+exit 0