nfp: register devlink after app is created

Devlink used to have two global locks: devlink lock and port lock,
our lock ordering looked like this:

  devlink lock -> driver's pf->lock -> devlink port lock

After recent changes port lock was replaced with per-instance
lock.  Unfortunately, new per-instance lock is taken on most
operations now.  This means we can only grab the pf->lock from
the port split/unsplit ops.  Lock ordering looks like this:

  devlink lock -> driver's pf->lock -> devlink instance lock

Since we can't take pf->lock from most devlink ops, make sure
nfp_apps are prepared to service them as soon as devlink is
registered.  Locking the pf must be pushed down after
nfp_app_init() callback.

The init order looks like this:
 nfp_app_init
 devlink_register
 nfp_app_start
 netdev/port_register

As soon as app_init is done nfp_apps must be ready to service
devlink-related callbacks.  apps can only register their own
devlink objects from nfp_app_start.

Fixes: 2406e7e ("devlink: Add per devlink instance lock")
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Dirk van der Merwe <dirk.vandermerwe@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/netronome/nfp/nfp_devlink.c

@@ -152,18 +152,8 @@ nfp_devlink_port_unsplit(struct devlink *devlink, unsigned int port_index)
 static int nfp_devlink_eswitch_mode_get(struct devlink *devlink, u16 *mode)
 {
 	struct nfp_pf *pf = devlink_priv(devlink);
-	int ret;
-
-	mutex_lock(&pf->lock);
-	if (!pf->app) {
-		ret = -EBUSY;
-		goto out;
-	}
-	ret = nfp_app_eswitch_mode_get(pf->app, mode);
-out:
-	mutex_unlock(&pf->lock);
 
-	return ret;
+	return nfp_app_eswitch_mode_get(pf->app, mode);
 }
 
 const struct devlink_ops nfp_devlink_ops = {

drivers/net/ethernet/netronome/nfp/nfp_main.c

@@ -499,13 +499,9 @@ static int nfp_pci_probe(struct pci_dev *pdev,
 	if (err)
 		goto err_hwinfo_free;
 
-	err = devlink_register(devlink, &pdev->dev);
-	if (err)
-		goto err_hwinfo_free;
-
 	err = nfp_nsp_init(pdev, pf);
 	if (err)
-		goto err_devlink_unreg;
+		goto err_hwinfo_free;
 
 	pf->mip = nfp_mip_open(pf->cpp);
 	pf->rtbl = __nfp_rtsym_table_read(pf->cpp, pf->mip);
@@ -549,8 +545,6 @@ static int nfp_pci_probe(struct pci_dev *pdev,
 	kfree(pf->eth_tbl);
 	kfree(pf->nspi);
 	vfree(pf->dumpspec);
-err_devlink_unreg:
-	devlink_unregister(devlink);
 err_hwinfo_free:
 	kfree(pf->hwinfo);
 	nfp_cpp_free(pf->cpp);
@@ -571,18 +565,13 @@ static int nfp_pci_probe(struct pci_dev *pdev,
 static void nfp_pci_remove(struct pci_dev *pdev)
 {
 	struct nfp_pf *pf = pci_get_drvdata(pdev);
-	struct devlink *devlink;
 
 	nfp_hwmon_unregister(pf);
 
-	devlink = priv_to_devlink(pf);
-
-	nfp_net_pci_remove(pf);
-
 	nfp_pcie_sriov_disable(pdev);
 	pci_sriov_set_totalvfs(pf->pdev, 0);
 
-	devlink_unregister(devlink);
+	nfp_net_pci_remove(pf);
 
 	vfree(pf->dumpspec);
 	kfree(pf->rtbl);
@@ -598,7 +587,7 @@ static void nfp_pci_remove(struct pci_dev *pdev)
 	kfree(pf->eth_tbl);
 	kfree(pf->nspi);
 	mutex_destroy(&pf->lock);
-	devlink_free(devlink);
+	devlink_free(priv_to_devlink(pf));
 	pci_release_regions(pdev);
 	pci_disable_device(pdev);
 }

drivers/net/ethernet/netronome/nfp/nfp_net_main.c

@@ -373,7 +373,9 @@ nfp_net_pf_app_init(struct nfp_pf *pf, u8 __iomem *qc_bar, unsigned int stride)
 	if (IS_ERR(pf->app))
 		return PTR_ERR(pf->app);
 
+	mutex_lock(&pf->lock);
 	err = nfp_app_init(pf->app);
+	mutex_unlock(&pf->lock);
 	if (err)
 		goto err_free;
 
@@ -401,7 +403,9 @@ nfp_net_pf_app_init(struct nfp_pf *pf, u8 __iomem *qc_bar, unsigned int stride)
 err_unmap:
 	nfp_cpp_area_release_free(pf->ctrl_vnic_bar);
 err_app_clean:
+	mutex_lock(&pf->lock);
 	nfp_app_clean(pf->app);
+	mutex_unlock(&pf->lock);
 err_free:
 	nfp_app_free(pf->app);
 	pf->app = NULL;
@@ -414,7 +418,11 @@ static void nfp_net_pf_app_clean(struct nfp_pf *pf)
 		nfp_net_pf_free_vnic(pf, pf->ctrl_vnic);
 		nfp_cpp_area_release_free(pf->ctrl_vnic_bar);
 	}
+
+	mutex_lock(&pf->lock);
 	nfp_app_clean(pf->app);
+	mutex_unlock(&pf->lock);
+
 	nfp_app_free(pf->app);
 	pf->app = NULL;
 }
@@ -693,6 +701,7 @@ int nfp_net_refresh_eth_port(struct nfp_port *port)
  */
 int nfp_net_pci_probe(struct nfp_pf *pf)
 {
+	struct devlink *devlink = priv_to_devlink(pf);
 	struct nfp_net_fw_version fw_ver;
 	u8 __iomem *ctrl_bar, *qc_bar;
 	int stride;
@@ -706,16 +715,13 @@ int nfp_net_pci_probe(struct nfp_pf *pf)
 		return -EINVAL;
 	}
 
-	mutex_lock(&pf->lock);
 	pf->max_data_vnics = nfp_net_pf_get_num_ports(pf);
-	if ((int)pf->max_data_vnics < 0) {
-		err = pf->max_data_vnics;
-		goto err_unlock;
-	}
+	if ((int)pf->max_data_vnics < 0)
+		return pf->max_data_vnics;
 
 	err = nfp_net_pci_map_mem(pf);
 	if (err)
-		goto err_unlock;
+		return err;
 
 	ctrl_bar = nfp_cpp_area_iomem(pf->data_vnic_bar);
 	qc_bar = nfp_cpp_area_iomem(pf->qc_area);
@@ -754,6 +760,11 @@ int nfp_net_pci_probe(struct nfp_pf *pf)
 	if (err)
 		goto err_unmap;
 
+	err = devlink_register(devlink, &pf->pdev->dev);
+	if (err)
+		goto err_app_clean;
+
+	mutex_lock(&pf->lock);
 	pf->ddir = nfp_net_debugfs_device_add(pf->pdev);
 
 	/* Allocate the vnics and do basic init */
@@ -785,12 +796,13 @@ int nfp_net_pci_probe(struct nfp_pf *pf)
 	nfp_net_pf_free_vnics(pf);
 err_clean_ddir:
 	nfp_net_debugfs_dir_clean(&pf->ddir);
+	mutex_unlock(&pf->lock);
+	cancel_work_sync(&pf->port_refresh_work);
+	devlink_unregister(devlink);
+err_app_clean:
 	nfp_net_pf_app_clean(pf);
 err_unmap:
 	nfp_net_pci_unmap_mem(pf);
-err_unlock:
-	mutex_unlock(&pf->lock);
-	cancel_work_sync(&pf->port_refresh_work);
 	return err;
 }
 
@@ -810,11 +822,13 @@ void nfp_net_pci_remove(struct nfp_pf *pf)
 	/* stop app first, to avoid double free of ctrl vNIC's ddir */
 	nfp_net_debugfs_dir_clean(&pf->ddir);
 
+	mutex_unlock(&pf->lock);
+
+	devlink_unregister(priv_to_devlink(pf));
+
 	nfp_net_pf_free_irqs(pf);
 	nfp_net_pf_app_clean(pf);
 	nfp_net_pci_unmap_mem(pf);
 
-	mutex_unlock(&pf->lock);
-
 	cancel_work_sync(&pf->port_refresh_work);
 }