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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS 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 6517BC10F14 for ; Wed, 10 Apr 2019 11:09:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3A7FB222B6 for ; Wed, 10 Apr 2019 11:09:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730465AbfDJLJQ (ORCPT ); Wed, 10 Apr 2019 07:09:16 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:58812 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729727AbfDJLFt (ORCPT ); Wed, 10 Apr 2019 07:05:49 -0400 Received: from localhost ([127.0.0.1] helo=nanos.tec.linutronix.de) by Galois.linutronix.de with esmtp (Exim 4.80) (envelope-from ) id 1hEB35-000564-C5; Wed, 10 Apr 2019 13:05:47 +0200 Message-Id: <20190410103645.048761764@linutronix.de> User-Agent: quilt/0.65 Date: Wed, 10 Apr 2019 12:28:10 +0200 From: Thomas Gleixner To: LKML Cc: Josh Poimboeuf , x86@kernel.org, Andy Lutomirski , Steven Rostedt , Alexander Potapenko Subject: [RFC patch 16/41] tracing: Remove the ULONG_MAX stack trace hackery References: <20190410102754.387743324@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org No architecture terminates the stack trace with ULONG_MAX anymore. As the code checks the number of entries stored anyway there is no point in keeping all that ULONG_MAX magic around. The histogram code zeroes the storage before saving the stack, so if the trace is shorter than the maximum number of entries it can terminate the print loop if a zero entry is detected. Signed-off-by: Thomas Gleixner Cc: Steven Rostedt --- kernel/trace/trace_events_hist.c | 2 +- kernel/trace/trace_stack.c | 20 +++++--------------- 2 files changed, 6 insertions(+), 16 deletions(-) --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -5246,7 +5246,7 @@ static void hist_trigger_stacktrace_prin unsigned int i; for (i = 0; i < max_entries; i++) { - if (stacktrace_entries[i] == ULONG_MAX) + if (!stacktrace_entries[i]) return; seq_printf(m, "%*c", 1 + spaces, ' '); --- a/kernel/trace/trace_stack.c +++ b/kernel/trace/trace_stack.c @@ -18,8 +18,7 @@ #include "trace.h" -static unsigned long stack_dump_trace[STACK_TRACE_ENTRIES+1] = - { [0 ... (STACK_TRACE_ENTRIES)] = ULONG_MAX }; +static unsigned long stack_dump_trace[STACK_TRACE_ENTRIES + 1]; unsigned stack_trace_index[STACK_TRACE_ENTRIES]; /* @@ -52,10 +51,7 @@ void stack_trace_print(void) stack_trace_max.nr_entries); for (i = 0; i < stack_trace_max.nr_entries; i++) { - if (stack_dump_trace[i] == ULONG_MAX) - break; - if (i+1 == stack_trace_max.nr_entries || - stack_dump_trace[i+1] == ULONG_MAX) + if (i + 1 == stack_trace_max.nr_entries) size = stack_trace_index[i]; else size = stack_trace_index[i] - stack_trace_index[i+1]; @@ -150,8 +146,6 @@ check_stack(unsigned long ip, unsigned l p = start; for (; p < top && i < stack_trace_max.nr_entries; p++) { - if (stack_dump_trace[i] == ULONG_MAX) - break; /* * The READ_ONCE_NOCHECK is used to let KASAN know that * this is not a stack-out-of-bounds error. @@ -183,8 +177,6 @@ check_stack(unsigned long ip, unsigned l } stack_trace_max.nr_entries = x; - for (; x < i; x++) - stack_dump_trace[x] = ULONG_MAX; if (task_stack_end_corrupted(current)) { stack_trace_print(); @@ -286,7 +278,7 @@ static void * { long n = *pos - 1; - if (n >= stack_trace_max.nr_entries || stack_dump_trace[n] == ULONG_MAX) + if (n >= stack_trace_max.nr_entries) return NULL; m->private = (void *)n; @@ -360,12 +352,10 @@ static int t_show(struct seq_file *m, vo i = *(long *)v; - if (i >= stack_trace_max.nr_entries || - stack_dump_trace[i] == ULONG_MAX) + if (i >= stack_trace_max.nr_entries) return 0; - if (i+1 == stack_trace_max.nr_entries || - stack_dump_trace[i+1] == ULONG_MAX) + if (i + 1 == stack_trace_max.nr_entries) size = stack_trace_index[i]; else size = stack_trace_index[i] - stack_trace_index[i+1];