Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754441AbaLKSQc (ORCPT ); Thu, 11 Dec 2014 13:16:32 -0500 Received: from mail-wg0-f41.google.com ([74.125.82.41]:40103 "EHLO mail-wg0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750737AbaLKSQb (ORCPT ); Thu, 11 Dec 2014 13:16:31 -0500 From: Gabriele Mazzotta To: Mika Westerberg Cc: linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, benjamin.tissoires@redhat.com, aduggan@synaptics.com, jkosina@suse.cz Subject: Re: NULL pointer dereference in i2c-hid Date: Thu, 11 Dec 2014 19:16:28 +0100 Message-ID: <2128690.c90ERDd9ZP@xps13> User-Agent: KMail/4.14.2 (Linux/3.18.0+; KDE/4.14.2; x86_64; ; ) In-Reply-To: <20141211140307.GE1300@lahna.fi.intel.com> References: <31518562.V5Oyo0POsI@xps13> <20141211085801.GR1300@lahna.fi.intel.com> <20141211140307.GE1300@lahna.fi.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday 11 December 2014 16:03:07 Mika Westerberg wrote: > On Thu, Dec 11, 2014 at 10:58:01AM +0200, Mika Westerberg wrote: > > On Wed, Dec 10, 2014 at 06:04:51PM +0100, Gabriele Mazzotta wrote: > > > my laptop uses a touchpad that needs hid-rmi along with i2c-hid to work. > > > i2c-hid and hid-rmi can be loaded and unloaded independelty from each > > > other, however since 34f439e4afcd ("HID: i2c-hid: add runtime PM support") > > > if I unload hid-rmi and after it I also unload i2c-hid, I get a NULL > > > pointer dereference. > > > > I'll look into this. > > > > I can reproduce this easily with i2c-hid + hid-multitouch following your > > directions. > > Can you try the below patch? > > I think we shouldn't free buffers yet in ->stop() because we need the > command buffer sending power commands to the device. Also it seems that > ->start() re-allocates buffers anyway if maximum size increases. > > It shouldn't even leak memory as we release buffers at ->remove() > anyway. > > diff --git a/drivers/hid/i2c-hid/i2c-hid.c b/drivers/hid/i2c-hid/i2c-hid.c > index 62cec01937ea..68a8c938feea 100644 > --- a/drivers/hid/i2c-hid/i2c-hid.c > +++ b/drivers/hid/i2c-hid/i2c-hid.c > @@ -705,12 +705,7 @@ static int i2c_hid_start(struct hid_device *hid) > > static void i2c_hid_stop(struct hid_device *hid) > { > - struct i2c_client *client = hid->driver_data; > - struct i2c_hid *ihid = i2c_get_clientdata(client); > - > hid->claimed = 0; > - > - i2c_hid_free_buffers(ihid); > } > > static int i2c_hid_open(struct hid_device *hid) Yes, it works, thanks. This change seems to also prevent kernel ooops when I unload either i2c-hid or i2c-designware-platform while the touchpad is in use, thing that is likely to happen because of the other bug I reported. Speaking of it, does any of you have any suggestion on how to debug it? -- 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/