netdev - Re: [PATCH net-next] strparser: Return if socket does not have required number of bytes

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Date:   Wed, 30 Jan 2019 21:59:50 -0800 (PST)
From:   David Miller <davem@...emloft.net>
To:     vakul.garg@....com
Cc:     netdev@...r.kernel.org, borisp@...lanox.com, aviadye@...lanox.com,
        davejwatson@...com, doronrk@...com
Subject: Re: [PATCH net-next] strparser: Return if socket does not have
 required number of bytes

From: Vakul Garg <vakul.garg@....com>
Date: Wed, 30 Jan 2019 07:31:44 +0000

> Function strp_data_ready() should peek the associated socket to check
> whether it has the required number of bytes available before queueing
> work or initiating socket read via strp_read_sock(). This saves cpu
> cycles because strp_read_sock() is called only when required amount of
> data is available.
> 
> Signed-off-by: Vakul Garg <vakul.garg@....com>

You can't do this, I think.  It's racy and the user socket owned check
is absolutely necessary before you do the need bytes check.