Merge tag 'trace-v5.7-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull more tracing fixes from Steven Rostedt:
 "Various tracing fixes:

   - Fix a crash when having function tracing and function stack tracing
     on the command line.

     The ftrace trampolines are created as executable and read only. But
     the stack tracer tries to modify them with text_poke() which
     expects all kernel text to still be writable at boot. Keep the
     trampolines writable at boot, and convert them to read-only with
     the rest of the kernel.

   - A selftest was triggering in the ring buffer iterator code, that is
     no longer valid with the update of keeping the ring buffer writable
     while a iterator is reading.

     Just bail after three failed attempts to get an event and remove
     the warning and disabling of the ring buffer.

   - While modifying the ring buffer code, decided to remove all the
     unnecessary BUG() calls"

* tag 'trace-v5.7-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  ring-buffer: Remove all BUG() calls
  ring-buffer: Don't deactivate the ring buffer on failed iterator reads
  x86/ftrace: Have ftrace trampolines turn read-only at the end of system boot up

1 files changed, 23 insertions, 0 deletions

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index db95244a62d4..ab4bd15cbcdb 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -210,6 +210,29 @@ struct ftrace_ops {
 #endif
 };
 
+extern struct ftrace_ops __rcu *ftrace_ops_list;
+extern struct ftrace_ops ftrace_list_end;
+
+/*
+ * Traverse the ftrace_global_list, invoking all entries.  The reason that we
+ * can use rcu_dereference_raw_check() is that elements removed from this list
+ * are simply leaked, so there is no need to interact with a grace-period
+ * mechanism.  The rcu_dereference_raw_check() calls are needed to handle
+ * concurrent insertions into the ftrace_global_list.
+ *
+ * Silly Alpha and silly pointer-speculation compiler optimizations!
+ */
+#define do_for_each_ftrace_op(op, list)			\
+	op = rcu_dereference_raw_check(list);			\
+	do
+
+/*
+ * Optimized for just a single item in the list (as that is the normal case).
+ */
+#define while_for_each_ftrace_op(op)				\
+	while (likely(op = rcu_dereference_raw_check((op)->next)) &&	\
+	       unlikely((op) != &ftrace_list_end))
+
 /*
  * Type of the current tracing.
  */