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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 D8A8DC433E0 for ; Fri, 15 Jan 2021 00:14:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A4213221FD for ; Fri, 15 Jan 2021 00:14:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731207AbhAOAOe (ORCPT ); Thu, 14 Jan 2021 19:14:34 -0500 Received: from mx2.suse.de ([195.135.220.15]:46042 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729277AbhAOAOd (ORCPT ); Thu, 14 Jan 2021 19:14:33 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id D0993AC24; Fri, 15 Jan 2021 00:13:51 +0000 (UTC) From: Davidlohr Bueso To: jason.wessel@windriver.com Cc: daniel.thompson@linaro.org, kgdb-bugreport@lists.sourceforge.net, linux-kernel@vger.kernel.org, dave@stgolabs.net, Davidlohr Bueso Subject: [PATCH] kgdb: Schedule breakpoints via workqueue Date: Thu, 14 Jan 2021 16:13:44 -0800 Message-Id: <20210115001344.117108-1-dave@stgolabs.net> X-Mailer: git-send-email 2.26.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The original functionality was added back in: 1cee5e35f15 (kgdb: Add the ability to schedule a breakpoint via a tasklet) However tasklets have long been deprecated as being too heavy on the system by running in irq context - and this is not a performance critical path. If a higher priority process wants to run, it must wait for the tasklet to finish before doing so. Instead, generate the breakpoint exception in process context. Signed-off-by: Davidlohr Bueso --- Compile-tested only. kernel/debug/debug_core.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c index af6e8b4fb359..e1ff974c6b6f 100644 --- a/kernel/debug/debug_core.c +++ b/kernel/debug/debug_core.c @@ -119,7 +119,7 @@ static DEFINE_RAW_SPINLOCK(dbg_slave_lock); */ static atomic_t masters_in_kgdb; static atomic_t slaves_in_kgdb; -static atomic_t kgdb_break_tasklet_var; +static atomic_t kgdb_break_work_var; atomic_t kgdb_setting_breakpoint; struct task_struct *kgdb_usethread; @@ -1085,27 +1085,27 @@ static void kgdb_unregister_callbacks(void) } /* - * There are times a tasklet needs to be used vs a compiled in + * There are times a workqueue needs to be used vs a compiled in * break point so as to cause an exception outside a kgdb I/O module, * such as is the case with kgdboe, where calling a breakpoint in the * I/O driver itself would be fatal. */ -static void kgdb_tasklet_bpt(unsigned long ing) +static void kgdb_work_bpt(struct work_struct *unused) { kgdb_breakpoint(); - atomic_set(&kgdb_break_tasklet_var, 0); + atomic_set(&kgdb_break_work_var, 0); } -static DECLARE_TASKLET_OLD(kgdb_tasklet_breakpoint, kgdb_tasklet_bpt); +static DECLARE_WORK(kgdb_async_breakpoint, kgdb_work_bpt); void kgdb_schedule_breakpoint(void) { - if (atomic_read(&kgdb_break_tasklet_var) || + if (atomic_read(&kgdb_break_work_var) || atomic_read(&kgdb_active) != -1 || atomic_read(&kgdb_setting_breakpoint)) return; - atomic_inc(&kgdb_break_tasklet_var); - tasklet_schedule(&kgdb_tasklet_breakpoint); + atomic_inc(&kgdb_break_work_var); + schedule_work(&kgdb_async_breakpoint); } EXPORT_SYMBOL_GPL(kgdb_schedule_breakpoint); -- 2.26.2