From: Eric Dumazet <edumazet@google.com>
To: David Howells <dhowells@redhat.com>
Cc: "David S . Miller" <davem@davemloft.net>,
netdev <netdev@vger.kernel.org>,
Eric Dumazet <eric.dumazet@gmail.com>,
Jakub Kicinski <jakub.kicinski@netronome.com>
Subject: Re: [PATCH net] rxrpc: use rcu protection while reading sk->sk_user_data
Date: Wed, 16 Oct 2019 16:35:01 -0700 [thread overview]
Message-ID: <CANn89iL9t78ta1JMecG7b8A+mNytfBy4_wXXYRD2Rosz8iFpVg@mail.gmail.com> (raw)
In-Reply-To: <8142.1571268276@warthog.procyon.org.uk>
On Wed, Oct 16, 2019 at 4:24 PM David Howells <dhowells@redhat.com> wrote:
>
> Eric Dumazet <edumazet@google.com> wrote:
>
> > We need to extend the rcu_read_lock() section in rxrpc_error_report()
> > and use rcu_dereference_sk_user_data() instead of plain access
> > to sk->sk_user_data to make sure all rules are respected.
>
> Should I take it that the caller won't be guaranteed to be holding the RCU
> read lock?
>
> Looking at __udp4_lib_err(), that calls __udp4_lib_err_encap(), which calls
> __udp4_lib_err_encap_no_sk(), which should throw a warning if the RCU read
> lock is not held.
>
> Similarly, icmp_socket_deliver() and icmpv6_notify() should also throw a
> warning before calling ->err_handler().
>
> Does that mean something further up the CPU stack is going to be holding the
> RCU read lock?
Note that before my patch, the code had a rcu_read_lock()/rcu_read_unlock(),
so I only extended it.
I am not sure that all callers already have rcu_read_lock() held, I
prefer leaving this matter for net-next
>
> David
prev parent reply other threads:[~2019-10-16 23:35 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-14 13:04 [PATCH net] rxrpc: use rcu protection while reading sk->sk_user_data Eric Dumazet
2019-10-16 3:15 ` David Miller
2019-10-16 19:21 ` David Miller
2019-10-16 23:24 ` David Howells
2019-10-16 23:35 ` Eric Dumazet [this message]
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