nfp: don't hold PF lock while enabling SR-IOV

Enabling SR-IOV VFs will cause the PCI subsystem to schedule a
work and flush its workqueue.  Since the nfp driver schedules its
own work we can't enable VFs while holding driver load.  Commit
6d48ceb27af1 ("nfp: allocate a private workqueue for driver work")
tried to avoid this deadlock by creating a separate workqueue.
Unfortunately, due to the architecture of workqueue subsystem this
does not guarantee a separate thread of execution.  Luckily
we can simply take pci_enable_sriov() from under the driver lock.

Take pci_disable_sriov() from under the lock too for symmetry.

Fixes: 6d48ceb27af1 ("nfp: allocate a private workqueue for driver work")
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 7 insertions, 9 deletions

diff --git a/drivers/net/ethernet/netronome/nfp/nfp_main.c b/drivers/net/ethernet/netronome/nfp/nfp_main.c
index d67969d3e484..3f199db2002e 100644
--- a/drivers/net/ethernet/netronome/nfp/nfp_main.c
+++ b/drivers/net/ethernet/netronome/nfp/nfp_main.c
@@ -98,21 +98,20 @@ static int nfp_pcie_sriov_enable(struct pci_dev *pdev, int num_vfs)
         struct nfp_pf *pf = pci_get_drvdata(pdev);
         int err;
 
-        mutex_lock(&pf->lock);
-
         if (num_vfs > pf->limit_vfs) {
                 nfp_info(pf->cpp, "Firmware limits number of VFs to %u\n",
                          pf->limit_vfs);
-                err = -EINVAL;
-                goto err_unlock;
+                return -EINVAL;
         }
 
         err = pci_enable_sriov(pdev, num_vfs);
         if (err) {
                 dev_warn(&pdev->dev, "Failed to enable PCI SR-IOV: %d\n", err);
-                goto err_unlock;
+                return err;
         }
 
+        mutex_lock(&pf->lock);
+
         err = nfp_app_sriov_enable(pf->app, num_vfs);
         if (err) {
                 dev_warn(&pdev->dev,
@@ -129,9 +128,8 @@ static int nfp_pcie_sriov_enable(struct pci_dev *pdev, int num_vfs)
         return num_vfs;
 
 err_sriov_disable:
-        pci_disable_sriov(pdev);
-err_unlock:
         mutex_unlock(&pf->lock);
+        pci_disable_sriov(pdev);
         return err;
 #endif
         return 0;
@@ -158,10 +156,10 @@ static int nfp_pcie_sriov_disable(struct pci_dev *pdev)
 
         pf->num_vfs = 0;
 
+        mutex_unlock(&pf->lock);
+
         pci_disable_sriov(pdev);
         dev_dbg(&pdev->dev, "Removed VFs.\n");
-
-        mutex_unlock(&pf->lock);
 #endif
         return 0;
 }