Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751454AbaLQBSn (ORCPT ); Tue, 16 Dec 2014 20:18:43 -0500 Received: from lekensteyn.nl ([178.21.112.251]:52363 "EHLO lekensteyn.nl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750922AbaLQBSl (ORCPT ); Tue, 16 Dec 2014 20:18:41 -0500 From: Peter Wu To: Benjamin Tissoires Cc: Jiri Kosina , Nestor Lopez Casado , Peter Hutterer , linux-input@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] HID: logitech-hidpp: store the name of the device in struct hidpp Date: Wed, 17 Dec 2014 02:18:30 +0100 Message-ID: <3321911.knGKb1BsCe@al> User-Agent: KMail/4.14.3 (Linux/3.17.0-rc4-custom-00168-g7ec62d4; KDE/4.14.3; x86_64; ; ) In-Reply-To: <1418767562-4136-2-git-send-email-benjamin.tissoires@redhat.com> References: <1418767562-4136-1-git-send-email-benjamin.tissoires@redhat.com> <1418767562-4136-2-git-send-email-benjamin.tissoires@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Spam-Score: 0.0 (/) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday 16 December 2014 17:06:02 Benjamin Tissoires wrote: > If a disconnect occurs while getting the actual name of the device > (which can take several HID transactions), the name of the device will > be the hid name, provided by the Unifying Receiver. > This means that in some cases, the user space will see a different > name that what it usually sees when there is no disconnect. > > We should store the name of the device in the struct hidpp. That way, > if a disconnect occurs while we are accessing the name, > hidpp_connect_event() can fail, and the input node is not created. > > The input node will be created only if we have a connection which > lasts long enough to retrieve all the requested information: > name, protocol, and specific configuration. > > Signed-off-by: Benjamin Tissoires > --- > drivers/hid/hid-logitech-hidpp.c | 31 ++++++++++++++++++++----------- > 1 file changed, 20 insertions(+), 11 deletions(-) > > diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-logitech-hidpp.c > index c0fb5fe..4bc8714 100644 > --- a/drivers/hid/hid-logitech-hidpp.c > +++ b/drivers/hid/hid-logitech-hidpp.c > @@ -89,6 +89,7 @@ struct hidpp_device { > struct hid_device *hid_dev; > struct mutex send_mutex; > void *send_receive_buf; > + char *name; > wait_queue_head_t wait; > bool answer_available; > u8 protocol_major; > @@ -1087,6 +1088,7 @@ static void hidpp_input_close(struct input_dev *dev) > static struct input_dev *hidpp_allocate_input(struct hid_device *hdev) > { > struct input_dev *input_dev = devm_input_allocate_device(&hdev->dev); > + struct hidpp_device *hidpp = hid_get_drvdata(hdev); > > if (!input_dev) > return NULL; > @@ -1095,7 +1097,7 @@ static struct input_dev *hidpp_allocate_input(struct hid_device *hdev) > input_dev->open = hidpp_input_open; > input_dev->close = hidpp_input_close; > > - input_dev->name = hdev->name; > + input_dev->name = hidpp->name; > input_dev->phys = hdev->phys; > input_dev->uniq = hdev->uniq; > input_dev->id.bustype = hdev->bus; > @@ -1137,22 +1139,28 @@ static void hidpp_connect_event(struct hidpp_device *hidpp) > hid_info(hdev, "HID++ %u.%u device connected.\n", > hidpp->protocol_major, hidpp->protocol_minor); > > + if (!hidpp->name || hidpp->name == hdev->name) { Hm, is it ever possible that hidpp->name is NULL? probe sets the pointer to an array (hdev->name). Defence in depth I guess, but perhaps a comment could clarify this? Otherwise the changes look OK. I have tested this situation: 1. Insert receiver 2. Return a HID++ version for the WTP. 3. Return -9 (ResourceError) for the device name feature request (via the QEMU emulation). 4. Observe that this fails. So maybe you could add a comment for the above and add these tags: Reviewed-by: Peter Wu Tested-by: Peter Wu Kind regards, Peter > + name = hidpp_get_device_name(hidpp); > + if (!name) { > + hid_err(hdev, > + "unable to retrieve the name of the device"); > + return; > + } > + > + devm_name = devm_kasprintf(&hdev->dev, GFP_KERNEL, "%s", name); > + kfree(name); > + if (!devm_name) > + return; > + > + hidpp->name = devm_name; > + } > + > input = hidpp_allocate_input(hdev); > if (!input) { > hid_err(hdev, "cannot allocate new input device: %d\n", ret); > return; > } > > - name = hidpp_get_device_name(hidpp); > - if (!name) { > - hid_err(hdev, "unable to retrieve the name of the device"); > - } else { > - devm_name = devm_kasprintf(&hdev->dev, GFP_KERNEL, "%s", name); > - if (devm_name) > - input->name = devm_name; > - kfree(name); > - } > - > hidpp_populate_input(hidpp, input, false); > > ret = input_register_device(input); > @@ -1175,6 +1183,7 @@ static int hidpp_probe(struct hid_device *hdev, const struct hid_device_id *id) > return -ENOMEM; > > hidpp->hid_dev = hdev; > + hidpp->name = hdev->name; > hid_set_drvdata(hdev, hidpp); > > hidpp->quirks = id->driver_data; > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/