From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Henrik Rydberg" <rydberg@euromail.se>
Subject: Re: [PATCHv2] evdev: fix evdev_write return value on partial writes
Date: Thu, 27 Jan 2011 13:26:25 +0100
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To: Peter Korsgaard <jacmet@sunsite.dk>
Cc: dmitry.torokhov@gmail.com, linux-input@vger.kernel.org, baruch@tkos.co.il

On Thu, Jan 27, 2011 at 01:04:49PM +0100, Peter Korsgaard wrote:
> >>>>> "Henrik" == Henrik Rydberg <rydberg@euromail.se> writes:
> 
> Hi,
> 
>  Henrik> I won't argue against this case (with < 0) being frequent, but one
>  Henrik> should really check "n < len" to be safe. Hopefully Dmitry has some
>  Henrik> more input.
> 
> No, the point is that write (and read) can consume less data than
> requested, without it being an error. Robust userspace code should
> adjust buffer address / size and redo the work until all data is
> transferred or an error occurs.

Shouldn't the error be on (!len || len % smallest_acceptable_chunk),
then? Which makes me wonder about regressions - perhaps accumulating
partial writes in evdev is more safe from that perspective.

Thanks,
Henrik