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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,
        Roberto Bergantinos Corpas <rbergant@redhat.com>,
        Benjamin Coddington <bcodding@redhat.com>,
        Anna Schumaker <Anna.Schumaker@Netapp.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.14 038/193] NFS: make nfs_match_client killable
Date:   Wed, 29 May 2019 20:04:52 -0700
Message-Id: <20190530030454.763133741@linuxfoundation.org>
In-Reply-To: <20190530030446.953835040@linuxfoundation.org>
References: <20190530030446.953835040@linuxfoundation.org>
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[ Upstream commit 950a578c6128c2886e295b9c7ecb0b6b22fcc92b ]

    Actually we don't do anything with return value from
    nfs_wait_client_init_complete in nfs_match_client, as a
    consequence if we get a fatal signal and client is not
    fully initialised, we'll loop to "again" label

    This has been proven to cause soft lockups on some scenarios
    (no-carrier but configured network interfaces)

Signed-off-by: Roberto Bergantinos Corpas <rbergant@redhat.com>
Reviewed-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/nfs/client.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/fs/nfs/client.c b/fs/nfs/client.c
index a98d64a6eda5c..65da2c105f434 100644
--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -290,6 +290,7 @@ static struct nfs_client *nfs_match_client(const struct nfs_client_initdata *dat
 	struct nfs_client *clp;
 	const struct sockaddr *sap = data->addr;
 	struct nfs_net *nn = net_generic(data->net, nfs_net_id);
+	int error;
 
 again:
 	list_for_each_entry(clp, &nn->nfs_client_list, cl_share_link) {
@@ -302,8 +303,10 @@ static struct nfs_client *nfs_match_client(const struct nfs_client_initdata *dat
 		if (clp->cl_cons_state > NFS_CS_READY) {
 			atomic_inc(&clp->cl_count);
 			spin_unlock(&nn->nfs_client_lock);
-			nfs_wait_client_init_complete(clp);
+			error = nfs_wait_client_init_complete(clp);
 			nfs_put_client(clp);
+			if (error < 0)
+				return ERR_PTR(error);
 			spin_lock(&nn->nfs_client_lock);
 			goto again;
 		}
@@ -413,6 +416,8 @@ struct nfs_client *nfs_get_client(const struct nfs_client_initdata *cl_init)
 		clp = nfs_match_client(cl_init);
 		if (clp) {
 			spin_unlock(&nn->nfs_client_lock);
+			if (IS_ERR(clp))
+				return clp;
 			if (new)
 				new->rpc_ops->free_client(new);
 			return nfs_found_client(cl_init, clp);
-- 
2.20.1