Merge tag 'trace-v6.18-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull tracing fixes from Steven Rostedt:

 - Check for reader catching up in ring_buffer_map_get_reader()

   If the reader catches up to the writer in the memory mapped ring
   buffer then calling rb_get_reader_page() will return NULL as there's
   no pages left. But this isn't checked for before calling
   rb_get_reader_page() and the return of NULL causes a warning.

   If it is detected that the reader caught up to the writer, then
   simply exit the routine

 - Fix memory leak in histogram create_field_var()

   The couple of the error paths in create_field_var() did not properly
   clean up what was allocated. Make sure everything is freed properly
   on error

 - Fix help message of tools latency_collector

   The help message incorrectly stated that "-t" was the same as
   "--threads" whereas "--threads" is actually represented by "-e"

* tag 'trace-v6.18-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  tracing/tools: Fix incorrcet short option in usage text for --threads
  tracing: Fix memory leaks in create_field_var()
  ring-buffer: Do not warn in ring_buffer_map_get_reader() when reader catches up

Author: torvalds

kernel/trace/ring_buffer.c

@@ -7344,6 +7344,10 @@ int ring_buffer_map_get_reader(struct trace_buffer *buffer, int cpu)
 		goto out;
 	}
 
+	/* Did the reader catch up with the writer? */
+	if (cpu_buffer->reader_page == cpu_buffer->commit_page)
+		goto out;
+
 	reader = rb_get_reader_page(cpu_buffer);
 	if (WARN_ON(!reader))
 		goto out;

kernel/trace/trace_events_hist.c

@@ -3272,14 +3272,16 @@ static struct field_var *create_field_var(struct hist_trigger_data *hist_data,
 	var = create_var(hist_data, file, field_name, val->size, val->type);
 	if (IS_ERR(var)) {
 		hist_err(tr, HIST_ERR_VAR_CREATE_FIND_FAIL, errpos(field_name));
-		kfree(val);
+		destroy_hist_field(val, 0);
 		ret = PTR_ERR(var);
 		goto err;
 	}
 
 	field_var = kzalloc(sizeof(struct field_var), GFP_KERNEL);
 	if (!field_var) {
-		kfree(val);
+		destroy_hist_field(val, 0);
+		kfree_const(var->type);
+		kfree(var->var.name);
 		kfree(var);
 		ret =  -ENOMEM;
 		goto err;

tools/tracing/latency/latency-collector.c

@@ -1725,7 +1725,7 @@ static void show_usage(void)
 "-n, --notrace\t\tIf latency is detected, do not print out the content of\n"
 "\t\t\tthe trace file to standard output\n\n"
 
-"-t, --threads NRTHR\tRun NRTHR threads for printing. Default is %d.\n\n"
+"-e, --threads NRTHR\tRun NRTHR threads for printing. Default is %d.\n\n"
 
 "-r, --random\t\tArbitrarily sleep a certain amount of time, default\n"
 "\t\t\t%ld ms, before reading the trace file. The\n"