Message-ID: <4D83CB7C.8040903@keymile.com>
Date: Fri, 18 Mar 2011 22:15:40 +0100
From: Stefan Bigler <stefan.bigler@keymile.com>
Reply-To: stefan.bigler@keymile.com
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To: Alan Cox <alan@lxorguk.ukuu.org.uk>
CC: Greg KH <greg@kroah.com>, linux-kernel@vger.kernel.org,
        linux-usb@vger.kernel.org
Subject: Re: TTY loosing data with u_serial gadget
References: <4D8121F6.9060600@keymile.com><20110317000408.GA18911@kroah.com><4D8389EC.5030704@keymile.com> <20110318180718.6d019c71@lxorguk.ukuu.org.uk>
In-Reply-To: <20110318180718.6d019c71@lxorguk.ukuu.org.uk>
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> In essence if you get a value from receive_room it's a guarantee you may
> send that many bytes, it is not a precise instantaneous perfect answer to
> the question "exactly what number of bytes could fit at this precise
> moment".
>
Hi

I have no problem with having more space available than guarantied by
the value of receive_room. But what I see is that the value can be less!
Data will be lost.
My test showed:
  data to queue=201
  receive_room (guarantied space) =287
  real space in queue =0
In the last mail I attached the code for printing, the read_lock was only
added to show a constistant view of all current values.

Stefan
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