From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 597AFC43387 for ; Fri, 21 Dec 2018 17:58:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 125A921920 for ; Fri, 21 Dec 2018 17:58:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391263AbeLUR5k (ORCPT ); Fri, 21 Dec 2018 12:57:40 -0500 Received: from mail.kernel.org ([198.145.29.99]:56322 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391159AbeLUR47 (ORCPT ); Fri, 21 Dec 2018 12:56:59 -0500 Received: from gandalf.local.home (cpe-66-24-56-78.stny.res.rr.com [66.24.56.78]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 72F0B21927; Fri, 21 Dec 2018 17:56:59 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.91) (envelope-from ) id 1gaP2g-0002Q3-Fd; Fri, 21 Dec 2018 12:56:58 -0500 Message-Id: <20181221175658.347685840@goodmis.org> User-Agent: quilt/0.65 Date: Fri, 21 Dec 2018 12:56:36 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Andrew Morton , Namhyung Kim , Masami Hiramatsu , Tom Zanussi Subject: [for-next][PATCH 18/24] tracing: Add hist trigger comments for variable-related fields References: <20181221175618.968519903@goodmis.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Tom Zanussi Add a few comments to help clarify how variable and variable reference fields are used in the code. Link: http://lkml.kernel.org/r/ea857ce948531d7bec712bbb0f38360aa1d378ec.1545161087.git.tom.zanussi@linux.intel.com Acked-by: Namhyung Kim Reviewed-by: Masami Hiramatsu Signed-off-by: Tom Zanussi Signed-off-by: Steven Rostedt (VMware) --- kernel/trace/trace_events_hist.c | 36 ++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index 1b1aee944588..c5448c103770 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -40,6 +40,16 @@ enum field_op_id { FIELD_OP_UNARY_MINUS, }; +/* + * A hist_var (histogram variable) contains variable information for + * hist_fields having the HIST_FIELD_FL_VAR or HIST_FIELD_FL_VAR_REF + * flag set. A hist_var has a variable name e.g. ts0, and is + * associated with a given histogram trigger, as specified by + * hist_data. The hist_var idx is the unique index assigned to the + * variable by the hist trigger's tracing_map. The idx is what is + * used to set a variable's value and, by a variable reference, to + * retrieve it. + */ struct hist_var { char *name; struct hist_trigger_data *hist_data; @@ -56,11 +66,29 @@ struct hist_field { const char *type; struct hist_field *operands[HIST_FIELD_OPERANDS_MAX]; struct hist_trigger_data *hist_data; + + /* + * Variable fields contain variable-specific info in var. + */ struct hist_var var; enum field_op_id operator; char *system; char *event_name; + + /* + * The name field is used for EXPR and VAR_REF fields. VAR + * fields contain the variable name in var.name. + */ char *name; + + /* + * When a histogram trigger is hit, if it has any references + * to variables, the values of those variables are collected + * into a var_ref_vals array by resolve_var_refs(). The + * current value of each variable is read from the tracing_map + * using the hist field's hist_var.idx and entered into the + * var_ref_idx entry i.e. var_ref_vals[var_ref_idx]. + */ unsigned int var_ref_idx; bool read_once; }; @@ -365,6 +393,14 @@ struct action_data { union { struct { + /* + * When a histogram trigger is hit, the values of any + * references to variables, including variables being passed + * as parameters to synthetic events, are collected into a + * var_ref_vals array. This var_ref_idx is the index of the + * first param in the array to be passed to the synthetic + * event invocation. + */ unsigned int var_ref_idx; char *match_event; char *match_event_system; -- 2.19.2