Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757886AbaLKRh3 (ORCPT ); Thu, 11 Dec 2014 12:37:29 -0500 Received: from mail-yk0-f169.google.com ([209.85.160.169]:33467 "EHLO mail-yk0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750702AbaLKRh1 (ORCPT ); Thu, 11 Dec 2014 12:37:27 -0500 MIME-Version: 1.0 In-Reply-To: <20141211153118.GF29747@mail.corp.redhat.com> References: <1418302280-14794-1-git-send-email-peter@lekensteyn.nl> <1418302280-14794-5-git-send-email-peter@lekensteyn.nl> <20141211153118.GF29747@mail.corp.redhat.com> From: Andrew de los Reyes Date: Thu, 11 Dec 2014 09:37:06 -0800 X-Google-Sender-Auth: pESyyIezvOvN8L2sDrB_56vmL9M Message-ID: Subject: Re: [PATCH 4/4] HID: logitech-hidpp: disable io in probe error path To: Benjamin Tissoires , Peter Wu Cc: Jiri Kosina , Nestor Lopez Casado , Andrew de los Reyes , Peter Hutterer , Linux Input , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu Dec 11 2014 at 7:31:43 AM Benjamin Tissoires wrote: > > On Dec 11 2014 or thereabouts, Peter Wu wrote: > > Balance a hid_device_io_start() call with hid_device_io_stop() in the > > error path. This avoids processing of HID reports when the probe fails > > which possibly leads to invalid memory access in hid_device_probe() as > > report_enum->report_id_hash might already be freed via > > hid_close_report(). > > Well spotted too! > > > > > hid_set_drvdata() is called before wtp_allocate, be consistent and clear > > drvdata too on the error path of wtp_allocate. > > This is not strictly speaking required. We will have a dangling value in > hdev->private_data, but this should be overwritten before the next use. > > Anyway, it makes sense to clean up after a failure, so the patch is > Reviewed-by: Benjamin Tissoires > > Cheers, > Benjamin > > > > > Signed-off-by: Peter Wu > > --- > > Hi Andrew, > > > > There are few users of hid_device_io_start/stop, this is the first one > > to get start/stop out of sync. Should the comment of > > hid_device_io_start() be updated to ensure that hid_device_io_stop() > > gets called before probe() returns? Or should the hid-core be changed to > > handle this out-of-sync issue: I do not have a strong opinion on this, and will defer to others. The reason I needed to communicate during probe() was to have the driver probe the actual device for details. In this use case, I would be okay to disable IO at the end of probe() and have it become reenabled via the normal (default) methods. -andrew > > > > if (ret) { > > if (hdev->io_started)) > > down(&hdev->driver_input_lock); > > hid_close_report(hdev); > > hdev->driver = NULL; > > } > > > > Is my observation correct or not that HID reports can arrive during > > hid_close_report() when io_started == true? > > > > Kind regards, > > Peter > > --- > > drivers/hid/hid-logitech-hidpp.c | 4 +++- > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-logitech-hidpp.c > > index 4292cc3..2f420c0 100644 > > --- a/drivers/hid/hid-logitech-hidpp.c > > +++ b/drivers/hid/hid-logitech-hidpp.c > > @@ -1121,7 +1121,7 @@ static int hidpp_probe(struct hid_device *hdev, const struct hid_device_id *id) > > if (hidpp->quirks & HIDPP_QUIRK_CLASS_WTP) { > > ret = wtp_allocate(hdev, id); > > if (ret) > > - return ret; > > + goto wtp_allocate_fail; > > } > > > > INIT_WORK(&hidpp->work, delayed_work_cb); > > @@ -1141,6 +1141,7 @@ static int hidpp_probe(struct hid_device *hdev, const struct hid_device_id *id) > > if (id->group != HID_GROUP_LOGITECH_DJ_DEVICE) { > > if (!connected) { > > hid_err(hdev, "Device not connected"); > > + hid_device_io_stop(hdev); > > goto hid_parse_fail; > > } > > > > @@ -1186,6 +1187,7 @@ hid_hw_start_fail: > > hid_parse_fail: > > cancel_work_sync(&hidpp->work); > > mutex_destroy(&hidpp->send_mutex); > > +wtp_allocate_fail: > > hid_set_drvdata(hdev, NULL); > > return ret; > > } > > -- > > 2.1.3 > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-input" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- 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/