From patchwork Sat Mar 16 02:34:43 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Liuye X-Patchwork-Id: 780808 Received: from h3cspam02-ex.h3c.com (smtp.h3c.com [60.191.123.50]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8CA6636C; Sat, 16 Mar 2024 02:35:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=60.191.123.50 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710556552; cv=none; b=TFyGgEWm0ZiOhl1yNQWj9JV/JykgmJMFCIbDsKsx51nacWThdwh+0O+N0mOynOepocpwhfp5jwO/8QFMfx6xTQnCrK9vp+oM+GtyWJFsFGNSWxLVwCBhLaK4lLuoubXCHBRiOXtVUplFwdinccrAb2YHfTEIK2jMBsSiuZzmxX8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710556552; c=relaxed/simple; bh=5UKXr0LrJ+AvmgLX9sd0roltdUUfyJdTU6vBDngQ5wk=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=Aih6BAb4VemZsGNGD6I/01KkGesau/1QxQcaMREC1cCcZUu+xan640NA+ATzhd4dCZxtj9m/SzqxsDIrPkW+gxwYhSs/+xuOykSmeVVFX1On+6hrw5YbmJQ55SmmZqWJ/X0CudumOyYLBl4TJadyxw0CEdvEqCTimHJYcbmvPK8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=h3c.com; spf=pass smtp.mailfrom=h3c.com; arc=none smtp.client-ip=60.191.123.50 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=h3c.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=h3c.com Received: from mail.maildlp.com ([172.25.15.154]) by h3cspam02-ex.h3c.com with ESMTP id 42G2YsDx090365; Sat, 16 Mar 2024 10:34:54 +0800 (GMT-8) (envelope-from liu.yeC@h3c.com) Received: from DAG6EX02-IMDC.srv.huawei-3com.com (unknown [10.62.14.11]) by mail.maildlp.com (Postfix) with ESMTP id F19132004BB2; Sat, 16 Mar 2024 10:36:27 +0800 (CST) Received: from localhost.localdomain (10.114.186.34) by DAG6EX02-IMDC.srv.huawei-3com.com (10.62.14.11) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.2.1258.27; Sat, 16 Mar 2024 10:34:54 +0800 From: To: CC: , , , , , , , Subject: [PATCH v1] kdb: Fix the deadlock issue in KDB debugging. Date: Sat, 16 Mar 2024 10:34:43 +0800 Message-ID: <20240316023443.101169-1-liu.yec@h3c.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20240314130916.GE202685@aspen.lan> References: <20240314130916.GE202685@aspen.lan> Precedence: bulk X-Mailing-List: linux-serial@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ClientProxiedBy: BJSMTP02-EX.srv.huawei-3com.com (10.63.20.133) To DAG6EX02-IMDC.srv.huawei-3com.com (10.62.14.11) X-DNSRBL: X-SPAM-SOURCE-CHECK: pass X-MAIL: h3cspam02-ex.h3c.com 42G2YsDx090365 From: LiuYe Currently, if CONFIG_KDB_KEYBOARD is enabled, then kgdboc will attempt to use schedule_work() to provoke a keyboard reset when transitioning out of the debugger and back to normal operation. This can cause deadlock because schedule_work() is not NMI-safe. example: BUG: spinlock lockup suspected on CPU#0, namex/10450 lock: 0xffff881ffe823980, .magic: dead4ead, .owner: namexx/21888, .owner_cpu: 1 ffff881741d00000 ffff881741c01000 0000000000000000 0000000000000000 ffff881740f58e78 ffff881741cffdd0 ffffffff8147a7fc ffff881740f58f20 Call Trace: [] ? __schedule+0x16d/0xac0 [] ? schedule+0x3c/0x90 [] ? schedule_hrtimeout_range_clock+0x10a/0x120 [] ? mutex_unlock+0xe/0x10 [] ? ep_scan_ready_list+0x1db/0x1e0 [] ? schedule_hrtimeout_range+0x13/0x20 [] ? ep_poll+0x27a/0x3b0 [] ? wake_up_q+0x70/0x70 [] ? SyS_epoll_wait+0xb8/0xd0 [] ? entry_SYSCALL_64_fastpath+0x12/0x75 CPU: 0 PID: 10450 Comm: namex Tainted: G O 4.4.65 #1 Hardware name: Insyde Purley/Type2 - Board Product Name1, BIOS 05.21.51.0036 07/19/2019 0000000000000000 ffff881ffe813c10 ffffffff8124e883 ffff881741c01000 ffff881ffe823980 ffff881ffe813c38 ffffffff810a7f7f ffff881ffe823980 000000007d2b7cd0 0000000000000001 ffff881ffe813c68 ffffffff810a80e0 Call Trace: <#DB> [] dump_stack+0x85/0xc2 [] spin_dump+0x7f/0x100 [] do_raw_spin_lock+0xa0/0x150 [] _raw_spin_lock+0x15/0x20 [] try_to_wake_up+0x176/0x3d0 [] wake_up_process+0x15/0x20 [] insert_work+0x81/0xc0 [] __queue_work+0x135/0x390 [] queue_work_on+0x46/0x90 [] kgdboc_post_exp_handler+0x48/0x70 [] kgdb_cpu_enter+0x598/0x610 [] kgdb_handle_exception+0xf2/0x1f0 [] __kgdb_notify+0x71/0xd0 [] kgdb_notify+0x35/0x70 [] notifier_call_chain+0x4a/0x70 [] notify_die+0x3d/0x50 [] do_int3+0x89/0x120 [] int3+0x44/0x80 Suggested-by: daniel.thompson@linaro.org Signed-off-by: LiuYe Signed-off-by: Daniel Thompson Signed-off-by: Daniel Thompson --- drivers/tty/serial/kgdboc.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/drivers/tty/serial/kgdboc.c b/drivers/tty/serial/kgdboc.c index 7ce7bb164..161b25ecc 100644 --- a/drivers/tty/serial/kgdboc.c +++ b/drivers/tty/serial/kgdboc.c @@ -22,6 +22,7 @@ #include #include #include +#include #define MAX_CONFIG_LEN 40 @@ -99,10 +100,17 @@ static void kgdboc_restore_input_helper(struct work_struct *dummy) static DECLARE_WORK(kgdboc_restore_input_work, kgdboc_restore_input_helper); +static void kgdboc_queue_restore_input_helper(struct irq_work *unused) +{ + schedule_work(&kgdboc_restore_input_work); +} + +static DEFINE_IRQ_WORK(kgdboc_restore_input_irq_work, kgdboc_queue_restore_input_helper); + static void kgdboc_restore_input(void) { if (likely(system_state == SYSTEM_RUNNING)) - schedule_work(&kgdboc_restore_input_work); + irq_work_queue(&kgdboc_restore_input_irq_work); } static int kgdboc_register_kbd(char **cptr) @@ -133,6 +141,7 @@ static void kgdboc_unregister_kbd(void) i--; } } + irq_work_sync(&kgdboc_restore_input_irq_work); flush_work(&kgdboc_restore_input_work); } #else /* ! CONFIG_KDB_KEYBOARD */