From patchwork Wed Apr 17 17:44:25 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jiri Kosina X-Patchwork-Id: 2455641 X-Patchwork-Delegate: jikos@jikos.cz Return-Path: X-Original-To: patchwork-linux-input@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork2.kernel.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by patchwork2.kernel.org (Postfix) with ESMTP id DD245DF23A for ; Wed, 17 Apr 2013 17:44:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965549Ab3DQRo2 (ORCPT ); Wed, 17 Apr 2013 13:44:28 -0400 Received: from cantor2.suse.de ([195.135.220.15]:40721 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965225Ab3DQRo1 (ORCPT ); Wed, 17 Apr 2013 13:44:27 -0400 Received: from relay1.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 4175DA3B99; Wed, 17 Apr 2013 19:44:26 +0200 (CEST) Date: Wed, 17 Apr 2013 10:44:25 -0700 (PDT) From: Jiri Kosina To: Benjamin Tissoires Cc: Dmitry Torokhov , Benjamin Tissoires , linux-input@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/4] HID: debugfs rework In-Reply-To: <1366220296-14346-1-git-send-email-benjamin.tissoires@redhat.com> Message-ID: References: <1366220296-14346-1-git-send-email-benjamin.tissoires@redhat.com> User-Agent: Alpine 2.00 (LNX 1167 2008-08-23) MIME-Version: 1.0 Sender: linux-input-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-input@vger.kernel.org On Wed, 17 Apr 2013, Benjamin Tissoires wrote: > Hi Jiri, > > This is a small rework of the HID debugfs. > I encountered a problem with multitouch devices: they have too much usages to > fit into the fixed size output buffer of 512. > So I digg a little, and end up with those 4 patches. Hi Benjamin, thanks, I will look into it and see whether I would be able to apply it still for 3.10 merge window. I also have a locking fix for HID-debugfs which I am going to apply shortly, but I am travelling this week, so I am in a bit degraded mode. For reference, locking fix below. From: Jiri Kosina Subject: [PATCH] HID: protect hid_debug_list Accesses to hid_device->hid_debug_list are not serialized properly, which could result in SMP concurrency issues when HID debugfs events are accessesed by multiple userspace processess. Serialize all the list operations by a mutex. Reported-by: Al Viro Signed-off-by: Jiri Kosina Reviewed-by: Benjamin Tissoires --- drivers/hid/hid-core.c | 1 + drivers/hid/hid-debug.c | 6 ++++++ include/linux/hid.h | 1 + 3 files changed, 8 insertions(+) diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c index 1129f49..e3b7123 100644 --- a/drivers/hid/hid-core.c +++ b/drivers/hid/hid-core.c @@ -2347,6 +2347,7 @@ struct hid_device *hid_allocate_device(void) init_waitqueue_head(&hdev->debug_wait); INIT_LIST_HEAD(&hdev->debug_list); + mutex_init(&hdev->debug_list_lock); sema_init(&hdev->driver_lock, 1); sema_init(&hdev->driver_input_lock, 1); diff --git a/drivers/hid/hid-debug.c b/drivers/hid/hid-debug.c index 933fff0..3337261 100644 --- a/drivers/hid/hid-debug.c +++ b/drivers/hid/hid-debug.c @@ -580,12 +580,14 @@ void hid_debug_event(struct hid_device *hdev, char *buf) int i; struct hid_debug_list *list; + mutex_lock(&hdev->debug_list_lock); list_for_each_entry(list, &hdev->debug_list, node) { for (i = 0; i < strlen(buf); i++) list->hid_debug_buf[(list->tail + i) % HID_DEBUG_BUFSIZE] = buf[i]; list->tail = (list->tail + i) % HID_DEBUG_BUFSIZE; } + mutex_unlock(&hdev->debug_list_lock); wake_up_interruptible(&hdev->debug_wait); } @@ -960,7 +962,9 @@ static int hid_debug_events_open(struct inode *inode, struct file *file) file->private_data = list; mutex_init(&list->read_mutex); + mutex_lock(&list->hdev->debug_list_lock); list_add_tail(&list->node, &list->hdev->debug_list); + mutex_unlock(&list->hdev->debug_list_lock); out: return err; @@ -1055,7 +1059,9 @@ static int hid_debug_events_release(struct inode *inode, struct file *file) { struct hid_debug_list *list = file->private_data; + mutex_lock(&list->hdev->debug_list_lock); list_del(&list->node); + mutex_unlock(&list->hdev->debug_list_lock); kfree(list->hid_debug_buf); kfree(list); diff --git a/include/linux/hid.h b/include/linux/hid.h index b7b5ff2..af1b86d 100644 --- a/include/linux/hid.h +++ b/include/linux/hid.h @@ -515,6 +515,7 @@ struct hid_device { /* device report descriptor */ struct dentry *debug_rdesc; struct dentry *debug_events; struct list_head debug_list; + struct mutex debug_list_lock; wait_queue_head_t debug_wait; };