linux-kernel - Re: [PATCH v2] i2c-hid: introduce HID over i2c specification implementation

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Date:	Fri, 9 Nov 2012 04:59:32 -0500
From:	Benjamin Tissoires <benjamin.tissoires@...il.com>
To:	Jiri Kosina <jkosina@...e.cz>
Cc:	Jiri Slaby <jslaby@...e.cz>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Stephane Chatty <chatty@...c.fr>, fabien.andre@...il.com,
	scott.liu@....com.tw, Jean Delvare <khali@...ux-fr.org>,
	JJ Ding <jj_ding@....com.tw>,
	Shubhrajyoti Datta <omaplinuxkernel@...il.com>,
	linux-i2c@...r.kernel.org, linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] i2c-hid: introduce HID over i2c specification implementation

Hi Jiri,

On Fri, Nov 9, 2012 at 4:49 AM, Jiri Kosina <jkosina@...e.cz> wrote:
> On Tue, 16 Oct 2012, Benjamin Tissoires wrote:
>
>> >> --- /dev/null
>> >> +++ b/drivers/hid/i2c-hid/i2c-hid.c
>> > ...
>> >> +static int i2c_hid_alloc_buffers(struct i2c_hid *ihid)
>> >> +{
>> >> +     /* the worst case is computed from the set_report command with a
>> >> +      * reportID > 15 and the maximum report length */
>> >> +     int args_len = sizeof(__u8) + /* optional ReportID byte */
>> >> +                    sizeof(__u16) + /* data register */
>> >> +                    sizeof(__u16) + /* size of the report */
>> >> +                    ihid->bufsize; /* report */
>> >> +
>> >> +     ihid->inbuf = kzalloc(ihid->bufsize, GFP_KERNEL);
>> >> +
>> >> +     if (!ihid->inbuf)
>> >> +             return -ENOMEM;
>> >> +
>> >> +     ihid->argsbuf = kzalloc(args_len, GFP_KERNEL);
>> >> +
>> >> +     if (!ihid->argsbuf) {
>> >> +             kfree(ihid->inbuf);
>> >> +             return -ENOMEM;
>> >> +     }
>> >> +
>> >> +     ihid->cmdbuf = kzalloc(sizeof(union command) + args_len, GFP_KERNEL);
>> >> +
>> >> +     if (!ihid->cmdbuf) {
>> >> +             kfree(ihid->inbuf);
>> >> +             kfree(ihid->argsbuf);
>> >> +             return -ENOMEM;
>> >> +     }
>> >> +
>> >> +     return 0;
>> >
>> > If this is called from hid_start and some of the latter allocation fails
>> > here, you free the buffers appropriately. However if another start
>> > occurs (e.g. by loading another module for that particular device), it
>> > will crash, as the buffers will remain unallocated because at this point
>> > ihid->bufsize == old_bufsize. You should set ihid->bufsize back to
>> > old_bufsize if i2c_hid_alloc_buffers fails and also set the pointers to
>> > NULL here.
>>
>> well spotted, thanks.
>> I'll change it in v3 then.
>
> Benjamin,
>
> just a quick check -- are you planning on submitting v3 eventually?

yes sure.
It was not on my top priority list since I started at Red Hat.
Moreover, I've been reported a bug yesterday with the set_report
command.

I'll need to do a few more tests before sending the v3.

If I send it by the end of the day or at the beginning of next week,
will it have a chance to land into 3.8?

Cheers,
Benjamin


>
> Thanks,
>
> --
> Jiri Kosina
> SUSE Labs
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