Merge tag 'trace-v6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull tracing updates from Steven Rostedt:

 - Add options to the osnoise tracer:
      - 'panic_on_stop' option that panics the kernel if osnoise is
        greater than some user defined threshold.
      - 'preempt' option, to test noise while preemption is disabled
      - 'irq' option, to test noise when interrupts are disabled

 - Add .percent and .graph suffix to histograms to give different
   outputs

 - Add nohitcount to disable showing hitcount in histogram output

 - Add new __cpumask() to trace event fields to annotate that a unsigned
   long array is a cpumask to user space and should be treated as one.

 - Add trace_trigger kernel command line parameter to enable trace event
   triggers at boot up. Useful to trace stack traces, disable tracing
   and take snapshots.

 - Fix x86/kmmio mmio tracer to work with the updates to lockdep

 - Unify the panic and die notifiers

 - Add back ftrace_expect reference that is used to extract more
   information in the ftrace_bug() code.

 - Have trigger filter parsing errors show up in the tracing error log.

 - Updated MAINTAINERS file to add kernel tracing mailing list and
   patchwork info

 - Use IDA to keep track of event type numbers.

 - And minor fixes and clean ups

* tag 'trace-v6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (44 commits)
  tracing: Fix cpumask() example typo
  tracing: Improve panic/die notifiers
  ftrace: Prevent RCU stall on PREEMPT_VOLUNTARY kernels
  tracing: Do not synchronize freeing of trigger filter on boot up
  tracing: Remove pointer (asterisk) and brackets from cpumask_t field
  tracing: Have trigger filter parsing errors show up in error_log
  x86/mm/kmmio: Remove redundant preempt_disable()
  tracing: Fix infinite loop in tracing_read_pipe on overflowed print_trace_line
  Documentation/osnoise: Add osnoise/options documentation
  tracing/osnoise: Add preempt and/or irq disabled options
  tracing/osnoise: Add PANIC_ON_STOP option
  Documentation/osnoise: Escape underscore of NO_ prefix
  tracing: Fix some checker warnings
  tracing/osnoise: Make osnoise_options static
  tracing: remove unnecessary trace_trigger ifdef
  ring-buffer: Handle resize in early boot up
  tracing/hist: Fix issue of losting command info in error_log
  tracing: Fix issue of missing one synthetic field
  tracing/hist: Fix out-of-bound write on 'action_data.var_ref_idx'
  tracing/hist: Fix wrong return value in parse_action_params()
  ...

1 files changed, 19 insertions, 9 deletions

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 8e842f68b9a5..442438b93fe9 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -163,7 +163,7 @@ static void ftrace_sync_ipi(void *data)
 static ftrace_func_t ftrace_ops_get_list_func(struct ftrace_ops *ops)
 {
 	/*
-	 * If this is a dynamic, RCU, or per CPU ops, or we force list func,
+	 * If this is a dynamic or RCU ops, or we force list func,
 	 * then it needs to call the list anyway.
 	 */
 	if (ops->flags & (FTRACE_OPS_FL_DYNAMIC | FTRACE_OPS_FL_RCU) ||
@@ -2762,6 +2762,19 @@ void __weak ftrace_arch_code_modify_post_process(void)
 {
 }
 
+static int update_ftrace_func(ftrace_func_t func)
+{
+	static ftrace_func_t save_func;
+
+	/* Avoid updating if it hasn't changed */
+	if (func == save_func)
+		return 0;
+
+	save_func = func;
+
+	return ftrace_update_ftrace_func(func);
+}
+
 void ftrace_modify_all_code(int command)
 {
 	int update = command & FTRACE_UPDATE_TRACE_FUNC;
@@ -2782,7 +2795,7 @@ void ftrace_modify_all_code(int command)
 	 * traced.
 	 */
 	if (update) {
-		err = ftrace_update_ftrace_func(ftrace_ops_list_func);
+		err = update_ftrace_func(ftrace_ops_list_func);
 		if (FTRACE_WARN_ON(err))
 			return;
 	}
@@ -2798,7 +2811,7 @@ void ftrace_modify_all_code(int command)
 		/* If irqs are disabled, we are in stop machine */
 		if (!irqs_disabled())
 			smp_call_function(ftrace_sync_ipi, NULL, 1);
-		err = ftrace_update_ftrace_func(ftrace_trace_function);
+		err = update_ftrace_func(ftrace_trace_function);
 		if (FTRACE_WARN_ON(err))
 			return;
 	}
@@ -3070,8 +3083,6 @@ out:
 	/*
 	 * Dynamic ops may be freed, we must make sure that all
 	 * callers are done before leaving this function.
-	 * The same goes for freeing the per_cpu data of the per_cpu
-	 * ops.
 	 */
 	if (ops->flags & FTRACE_OPS_FL_DYNAMIC) {
 		/*
@@ -4192,6 +4203,7 @@ match_records(struct ftrace_hash *hash, char *func, int len, char *mod)
 			}
 			found = 1;
 		}
+		cond_resched();
 	} while_for_each_ftrace_rec();
  out_unlock:
 	mutex_unlock(&ftrace_lock);
@@ -7518,8 +7530,6 @@ __ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
 		/*
 		 * Check the following for each ops before calling their func:
 		 *  if RCU flag is set, then rcu_is_watching() must be true
-		 *  if PER_CPU is set, then ftrace_function_local_disable()
-		 *                          must be false
 		 *  Otherwise test if the ip matches the ops filter
 		 *
 		 * If any of the above fails then the op->func() is not executed.
@@ -7569,8 +7579,8 @@ NOKPROBE_SYMBOL(arch_ftrace_ops_list_func);
 
 /*
  * If there's only one function registered but it does not support
- * recursion, needs RCU protection and/or requires per cpu handling, then
- * this function will be called by the mcount trampoline.
+ * recursion, needs RCU protection, then this function will be called
+ * by the mcount trampoline.
  */
 static void ftrace_ops_assist_func(unsigned long ip, unsigned long parent_ip,
 				   struct ftrace_ops *op, struct ftrace_regs *fregs)