nvme-tcp: use __dev_get_by_name instead dev_get_by_name for OPT_HOST_IFACE

dev_get_by_name() finds network device by name but it also increases the
reference count.

If a nvme-tcp queue is present and the network device driver is removed
before nvme_tcp, we will face the following continuous log:

  "kernel:unregister_netdevice: waiting for <eth> to become free. Usage count = 2"

And rmmod further halts. Similar case arises during reboot/shutdown
with nvme-tcp queue present and both never completes.

To fix this, use __dev_get_by_name() which finds network device by
name without increasing any reference counter.

Fixes: 3ede8f72a9a2 ("nvme-tcp: allow selecting the network interface for connections")
Signed-off-by: Omkar Kulkarni <okulkarni@marvell.com>
Signed-off-by: Shai Malin <smalin@marvell.com>
Signed-off-by: Prabhakar Kushwaha <pkushwaha@marvell.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
[hch: remove the ->ndev member entirely]
Signed-off-by: Christoph Hellwig <hch@lst.de>

diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index 12acfe0..8cb15ee 100644 (file)
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -123,7 +123,6 @@ struct nvme_tcp_ctrl {
        struct blk_mq_tag_set   admin_tag_set;
        struct sockaddr_storage addr;
        struct sockaddr_storage src_addr;
-       struct net_device       *ndev;
        struct nvme_ctrl        ctrl;
 
        struct work_struct      err_work;
@@ -2533,8 +2532,7 @@ static struct nvme_ctrl *nvme_tcp_create_ctrl(struct device *dev,
        }
 
        if (opts->mask & NVMF_OPT_HOST_IFACE) {
-               ctrl->ndev = dev_get_by_name(&init_net, opts->host_iface);
-               if (!ctrl->ndev) {
+               if (!__dev_get_by_name(&init_net, opts->host_iface)) {
                        pr_err("invalid interface passed: %s\n",
                               opts->host_iface);
                        ret = -ENODEV;