On Fri, 2018-01-19 at 14:36 +0100, Florian Westphal wrote:
> Mike Christie reports:
> Starting in 4.14 iscsi logins will fail around 50% of the time.
>
> Problem appears to be that iscsi_target_sk_data_ready() callback may
> return without doing anything in case it finds the login work queue
> is still blocked in sock_recvmsg().
>
> Nicholas Bellinger says:
> It would indicate users providing their own ->sk_data_ready() callback
> must be responsible for waking up a kthread context blocked on
> sock_recvmsg(..., MSG_WAITALL), when a second ->sk_data_ready() is
> received before the first sock_recvmsg(..., MSG_WAITALL) completes.
>
> So, do this and invoke the original data_ready() callback -- in
> case of tcp sockets this takes care of waking the thread.
>
> Disclaimer: I do not understand why this problem did not show up before
> tcp prequeue removal.
>
> Reported-by: Mike Christie <mchristi@xxxxxxxxxx>
> Bisected-by: Mike Christie <mchristi@xxxxxxxxxx>
> Tested-by: Mike Christie <mchristi@xxxxxxxxxx>
> Diagnosed-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
> Fixes: e7942d0633c4 ("tcp: remove prequeue support")
> Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
> ---
> drivers/target/iscsi/iscsi_target_nego.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/target/iscsi/iscsi_target_nego.c b/drivers/target/iscsi/iscsi_target_nego.c
> index b686e2ce9c0e..3723f8f419aa 100644
> --- a/drivers/target/iscsi/iscsi_target_nego.c
> +++ b/drivers/target/iscsi/iscsi_target_nego.c
> @@ -432,6 +432,9 @@ static void iscsi_target_sk_data_ready(struct sock *sk)
> if (test_and_set_bit(LOGIN_FLAGS_READ_ACTIVE, &conn->login_flags)) {
> write_unlock_bh(&sk->sk_callback_lock);
> pr_debug("Got LOGIN_FLAGS_READ_ACTIVE=1, conn: %p >>>>\n", conn);
> + if (WARN_ON(iscsi_target_sk_data_ready == conn->orig_data_ready))
> + return;
Is this WARN_ON() belonging to this fix ?
At least make it WARN_ON_ONCE() or pr_err_once()
> + conn->orig_data_ready(sk);
> return;
> }
>
