netdev - Re: [PATCH net-next] tcp: free request sock directly upon TFO or syncookies error

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Message-ID: <9e38cf35-ba6e-6af2-85e3-f4bc509408c3@gmail.com>
Date:   Tue, 19 Mar 2019 09:34:53 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Guillaume Nault <gnault@...hat.com>, netdev@...r.kernel.org
Cc:     Eric Dumazet <eric.dumazet@...il.com>
Subject: Re: [PATCH net-next] tcp: free request sock directly upon TFO or
 syncookies error



On 03/19/2019 08:05 AM, Guillaume Nault wrote:
> Since the request socket is created locally, it'd make more sense to
> use reqsk_free() instead of reqsk_put() in TFO and syncookies' error
> path.
> 
> However, tcp_get_cookie_sock() may set ->rsk_refcnt before freeing the
> socket; tcp_conn_request() may also have non-null ->rsk_refcnt because
> of tcp_try_fastopen(). In both cases 'req' hasn't been exposed
> to the outside world and is safe to free immediately, but that'd
> trigger the WARN_ON_ONCE in reqsk_free().
> 
> Define __reqsk_free() for these situations where we know nobody's
> referencing the socket, even though ->rsk_refcnt might be non-null.
> Now we can consolidate the error path of tcp_get_cookie_sock() and
> tcp_conn_request().
> 
> Signed-off-by: Guillaume Nault <gnault@...hat.com>

SGTM thanks

Signed-off-by: Eric Dumazet <edumazet@...gle.com>