Quoting Dan Smith (danms@xxxxxxxxxx):
> This patch is a superset of the previous attempt to store socket buffers
> with their owners. It defers the writing and reading of the socket buffers
> until after the end of the file phase to avoid a recursive nose-dive of
> checkpointing socket owners.
>
> This also moves the join logic to the deferqueue as well, since that too
> can lead us down a deep hole. The buffer restore logic may perform a join
> if it decides that the join is inevitable (but not yet performed) and
> necessary.
>
> Changes in v2:
> - Add comment about using deferqueue_add() in a function that could have
> been called during deferqueue_run()
> - Change 'ref' to 'objref' in several variable names
> - Move SOCK_DEAD flag detection to initial patch
> - Catch errors from unix_read_buffers(), even on the should-be-missing
> send buffers
>
> Signed-off-by: Dan Smith <danms@xxxxxxxxxx>
Looks fine to my unqualified eyes, except for:
> @@ -139,54 +241,125 @@ static int sock_read_buffer_sendmsg(struct ckpt_ctx *ctx, struct sock *sk)
> if (ret < 0)
> goto out;
>
> + msg.msg_name = addr;
> + msg.msg_namelen = addrlen;
> +
> + /* If peer is shutdown, unshutdown it for this process */
> + sock_shutdown = sk->sk_shutdown;
> + sk->sk_shutdown &= ~SHUTDOWN_MASK;
> +
> + /* Unshutdown peer too, if necessary */
> + if (unix_sk(sk)->peer) {
> + peer_shutdown = unix_sk(sk)->peer->sk_shutdown;
> + unix_sk(sk)->peer->sk_shutdown &= ~SHUTDOWN_MASK;
> + }
> +
> + /* Make sure there's room in the send buffer */
> + sndbuf = sk->sk_sndbuf;
> + if (capable(CAP_NET_ADMIN) &&
> + ((sk->sk_sndbuf - atomic_read(&sk->sk_wmem_alloc)) < len))
'capable' actually has an adverse effect of setting the PF_SUPERPRIV
flag on current. So if I don't misread this, you'll want to do the
length check first, then the capable check, in order to make sure
that PF_SUPERPRIV doesn't get set unless the privilege was actually
needed.
> + sk->sk_sndbuf += len;
> + else
> + sk->sk_sndbuf = sysctl_wmem_max;
-serge
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