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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Ursula Braun <ubraun@linux.ibm.com>,
        "David S. Miller" <davem@davemloft.net>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.18 26/53] net/smc: fix non-blocking connect problem
Date:   Thu, 18 Oct 2018 19:54:19 +0200
Message-Id: <20181018175421.524799261@linuxfoundation.org>
In-Reply-To: <20181018175416.561567978@linuxfoundation.org>
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4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ursula Braun <ubraun@linux.ibm.com>

[ Upstream commit 648a5a7aed346c3b8fe7c32a835edfb0dfbf4451 ]

In state SMC_INIT smc_poll() delegates polling to the internal
CLC socket. This means, once the connect worker has finished
its kernel_connect() step, the poll wake-up may occur. This is not
intended. The wake-up should occur from the wake up call in
smc_connect_work() after __smc_connect() has finished.
Thus in state SMC_INIT this patch now calls sock_poll_wait() on the
main SMC socket.

Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/smc/af_smc.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -612,7 +612,10 @@ static void smc_connect_work(struct work
 		smc->sk.sk_err = -rc;
 
 out:
-	smc->sk.sk_state_change(&smc->sk);
+	if (smc->sk.sk_err)
+		smc->sk.sk_state_change(&smc->sk);
+	else
+		smc->sk.sk_write_space(&smc->sk);
 	kfree(smc->connect_info);
 	smc->connect_info = NULL;
 	release_sock(&smc->sk);
@@ -1345,7 +1348,7 @@ static __poll_t smc_poll(struct file *fi
 		return EPOLLNVAL;
 
 	smc = smc_sk(sock->sk);
-	if ((sk->sk_state == SMC_INIT) || smc->use_fallback) {
+	if (smc->use_fallback) {
 		/* delegate to CLC child sock */
 		mask = smc->clcsock->ops->poll(file, smc->clcsock, wait);
 		sk->sk_err = smc->clcsock->sk->sk_err;