From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754356Ab2ITUsU (ORCPT ); Thu, 20 Sep 2012 16:48:20 -0400 Received: from smtprelay-b11.telenor.se ([62.127.194.20]:44581 "EHLO smtprelay-b11.telenor.se" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753700Ab2ITUsT (ORCPT ); Thu, 20 Sep 2012 16:48:19 -0400 X-SENDER-IP: [85.230.29.114] X-LISTENER: [smtp.bredband.net] X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: ArCIALV+W1BV5h1yPGdsb2JhbABFhSK3FgEBgQIZAQEBAR8ZDSeCIAEBBAEnExwjBQsIA0YUJQoaE4d9CgenbJI1FIxcbIMiYAOVY4EVhFuDRolVgVgj X-IronPort-AV: E=Sophos;i="4.80,456,1344204000"; d="scan'208";a="196607513" From: "Henrik Rydberg" Date: Thu, 20 Sep 2012 22:48:25 +0200 To: Kevin Daughtridge Cc: linux-input@vger.kernel.org, jkosina@suse.cz, linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org Subject: Re: [PATCH v3] HID: keep dev_rdesc unmodified and use it for comparisons Message-ID: <20120920204825.GA2455@polaris.bitmath.org> References: <505b67d0.jarbgcy4b522QzyI%kevin@kdau.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <505b67d0.jarbgcy4b522QzyI%kevin@kdau.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > The dev_rdesc member of the hid_device structure is meant to store the original > report descriptor received from the device, but it is currently passed to any > report_fixup method before it is copied to the rdesc member. This patch uses a > temporary buffer to shield dev_rdesc from the side effects of many HID drivers' > report_fixup implementations. > > usbhid's hid_post_reset checks the report descriptor currently returned by the > device against a descriptor that may have been modified by a driver's > report_fixup method. That leaves some devices nonfunctional after a resume, with > a "reset_resume error 1" reported. This patch checks the new descriptor against > the unmodified dev_rdesc instead and uses the original, instead of modified, > report size. > > BugLink: http://bugs.launchpad.net/bugs/1049623 > Signed-off-by: Kevin Daughtridge > --- Looks like it will work, thank you Kevin. The comments below are just suggestions, I am fine with the patch as is. > drivers/hid/hid-core.c | 16 +++++++++++++--- > drivers/hid/usbhid/hid-core.c | 6 +++--- > 2 files changed, 16 insertions(+), 6 deletions(-) > > Changed in this version: added a temporary buffer to work around report_fixup > inconsistencies; using dev_rsize instead of rsize to allocate and read new > descriptor. > > diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c > index 8bcd168..5de3bb3 100644 > --- a/drivers/hid/hid-core.c > +++ b/drivers/hid/hid-core.c > @@ -757,6 +757,7 @@ int hid_open_report(struct hid_device *device) > struct hid_item item; > unsigned int size; > __u8 *start; > + __u8 *buf; It is sad to have to add a temporary here. > __u8 *end; > int ret; > static int (*dispatch_type[])(struct hid_parser *parser, > @@ -775,12 +776,21 @@ int hid_open_report(struct hid_device *device) > return -ENODEV; > size = device->dev_rsize; > > + buf = kmemdup(start, size, GFP_KERNEL); > + if (buf == NULL) > + return -ENOMEM; > + > if (device->driver->report_fixup) > - start = device->driver->report_fixup(device, start, &size); > + start = device->driver->report_fixup(device, buf, &size); > + else > + start = buf; > > - device->rdesc = kmemdup(start, size, GFP_KERNEL); > - if (device->rdesc == NULL) > + start = kmemdup(start, size, GFP_KERNEL); > + kfree(buf); Changing the semantics of the callback did not seem appealing, but it does not prevent us from using our own version internally. So, how about something like this: static __u8 *hid_alloc_rdesc(struct hid_device *devicew, const __u8 *start, unsigned int *size) { __u8 *rdesc = kmemdup(start, *size, GFP_KERNEL); if (rdesc && device->driver->report_fixup) { __u8 *tmp = device->driver->report_fixup(device, rdesc, size); if (tmp != rdesc) { tmp = kmemdup(tmp, *size, GFP_KERNEL); kfree(rdesc); rdesc = tmp; } } return rdesc; } > + if (start == NULL) > return -ENOMEM; > + > + device->rdesc = start; > device->rsize = size; > > parser = vzalloc(sizeof(struct hid_parser)); > diff --git a/drivers/hid/usbhid/hid-core.c b/drivers/hid/usbhid/hid-core.c > index dedd8e4..8e0c4bf94 100644 > --- a/drivers/hid/usbhid/hid-core.c > +++ b/drivers/hid/usbhid/hid-core.c > @@ -1415,20 +1415,20 @@ static int hid_post_reset(struct usb_interface *intf) > * configuration descriptors passed, we already know that > * the size of the HID report descriptor has not changed. > */ > - rdesc = kmalloc(hid->rsize, GFP_KERNEL); > + rdesc = kmalloc(hid->dev_rsize, GFP_KERNEL); > if (!rdesc) { > dbg_hid("couldn't allocate rdesc memory (post_reset)\n"); > return 1; > } > status = hid_get_class_descriptor(dev, > interface->desc.bInterfaceNumber, > - HID_DT_REPORT, rdesc, hid->rsize); > + HID_DT_REPORT, rdesc, hid->dev_rsize); > if (status < 0) { > dbg_hid("reading report descriptor failed (post_reset)\n"); > kfree(rdesc); > return 1; > } > - status = memcmp(rdesc, hid->rdesc, hid->rsize); > + status = memcmp(rdesc, hid->dev_rdesc, hid->dev_rsize); > kfree(rdesc); > if (status != 0) { > dbg_hid("report descriptor changed\n"); Thanks, Henrik