Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751434AbdIOKCT (ORCPT ); Fri, 15 Sep 2017 06:02:19 -0400 Received: from szxga04-in.huawei.com ([45.249.212.190]:6485 "EHLO szxga04-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751135AbdIOKCQ (ORCPT ); Fri, 15 Sep 2017 06:02:16 -0400 From: nixiaoming To: , , , , CC: , , , Subject: [PATCH] tty fix oops when rmmod 8250 Date: Fri, 15 Sep 2017 17:45:55 +0800 Message-ID: <20170915094555.55333-1-nixiaoming@huawei.com> X-Mailer: git-send-email 2.11.0.1 MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.67.187.180] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A010205.59BBA526.004C,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2014-11-16 11:51:01, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: 8e1de8cf947fc0a25809b15f54420540 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3276 Lines: 81 After rmmod 8250.ko tty_kref_put starts kwork (release_one_tty) to release proc interface oops when accessing driver->driver_name in proc_tty_unregister_driver Use jprobe, found driver->driver_name point to 8250.ko static static struct uart_driver serial8250_reg .driver_name= serial, Use name in proc_dir_entry instead of driver->driver_name to fix oops test on linux 4.1.12: BUG: unable to handle kernel paging request at ffffffffa01979de IP: [] strchr+0x0/0x30 PGD 1a0d067 PUD 1a0e063 PMD 851c1f067 PTE 0 Oops: 0000 [#1] PREEMPT SMP Modules linked in: ... ... [last unloaded: 8250] CPU: 7 PID: 116 Comm: kworker/7:1 Tainted: G O 4.1.12 #1 Hardware name: Insyde RiverForest/Type2 - Board Product Name1, BIOS NE5KV904 12/21/2015 Workqueue: events release_one_tty task: ffff88085b684960 ti: ffff880852884000 task.ti: ffff880852884000 RIP: 0010:[] [] strchr+0x0/0x30 RSP: 0018:ffff880852887c90 EFLAGS: 00010282 RAX: ffffffff81a5eca0 RBX: ffffffffa01979de RCX: 0000000000000004 RDX: ffff880852887d10 RSI: 000000000000002f RDI: ffffffffa01979de RBP: ffff880852887cd8 R08: 0000000000000000 R09: ffff88085f5d94d0 R10: 0000000000000195 R11: 0000000000000000 R12: ffffffffa01979de R13: ffff880852887d00 R14: ffffffffa01979de R15: ffff88085f02e840 FS: 0000000000000000(0000) GS:ffff88085f5c0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffa01979de CR3: 0000000001a0c000 CR4: 00000000001406e0 Stack: ffffffff812349b1 ffff880852887cb8 ffff880852887d10 ffff88085f5cd6c2 ffff880852800a80 ffffffffa01979de ffff880852800a84 0000000000000010 ffff88085bb28bd8 ffff880852887d38 ffffffff812354f0 ffff880852887d08 Call Trace: [] ? __xlate_proc_name+0x71/0xd0 [] remove_proc_entry+0x40/0x180 [] ? _raw_spin_lock_irqsave+0x41/0x60 [] ? destruct_tty_driver+0x60/0xe0 [] proc_tty_unregister_driver+0x28/0x40 [] destruct_tty_driver+0x88/0xe0 [] tty_driver_kref_put+0x1d/0x20 [] release_one_tty+0x5a/0xd0 [] process_one_work+0x139/0x420 [] worker_thread+0x121/0x450 [] ? process_scheduled_works+0x40/0x40 [] kthread+0xec/0x110 [] ? tg_rt_schedulable+0x210/0x220 [] ? kthread_freezable_should_stop+0x80/0x80 [] ret_from_fork+0x42/0x70 [] ? kthread_freezable_should_stop+0x80/0x80 Signed-off-by: nixiaoming --- fs/proc/proc_tty.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/proc/proc_tty.c b/fs/proc/proc_tty.c index 901bd06..20e2c18 100644 --- a/fs/proc/proc_tty.c +++ b/fs/proc/proc_tty.c @@ -14,6 +14,7 @@ #include #include #include +#include "internal.h" /* * The /proc/tty directory inodes... @@ -164,7 +165,7 @@ void proc_tty_unregister_driver(struct tty_driver *driver) if (!ent) return; - remove_proc_entry(driver->driver_name, proc_tty_driver); + remove_proc_entry(ent->name, proc_tty_driver); driver->proc_entry = NULL; } -- 2.11.0.1