[PATCH net-next v2 4/6] enic: make enic_dev_enable/disable ref-counted

[Satish Kharat via B4 Relay]

From: Satish Kharat <satishkh@xxxxxxxxx>

Both the data path (ndo_open/ndo_stop) and the upcoming admin channel
need to enable and disable the vNIC device independently. Without
reference counting, closing the admin channel while the netdev is up
would inadvertently disable the entire device.

Add an enable_count to struct enic, protected by the existing
devcmd_lock. enic_dev_enable() issues CMD_ENABLE_WAIT only on the
first caller (0 -> 1 transition), and enic_dev_disable() issues
CMD_DISABLE only when the last caller releases (1 -> 0 transition).

No functional change for the current single-caller data path.

Signed-off-by: Satish Kharat <satishkh@xxxxxxxxx>
---
 drivers/net/ethernet/cisco/enic/enic.h     |  1 +
 drivers/net/ethernet/cisco/enic/enic_dev.c | 17 +++++++++++++----
 2 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/cisco/enic/enic.h b/drivers/net/ethernet/cisco/enic/enic.h
index 0fd9cd917132..67fd780b1fa1 100644
--- a/drivers/net/ethernet/cisco/enic/enic.h
+++ b/drivers/net/ethernet/cisco/enic/enic.h
@@ -260,6 +260,7 @@ struct enic {
 	u16 num_vfs;
 #endif
 	enum enic_vf_type vf_type;
+	unsigned int enable_count;
 	spinlock_t enic_api_lock;
 	bool enic_api_busy;
 	struct enic_port_profile *pp;
diff --git a/drivers/net/ethernet/cisco/enic/enic_dev.c b/drivers/net/ethernet/cisco/enic/enic_dev.c
index 2cbae7c6cc3d..659787f73cf1 100644
--- a/drivers/net/ethernet/cisco/enic/enic_dev.c
+++ b/drivers/net/ethernet/cisco/enic/enic_dev.c
@@ -131,10 +131,13 @@ int enic_dev_set_ig_vlan_rewrite_mode(struct enic *enic)
 
 int enic_dev_enable(struct enic *enic)
 {
-	int err;
+	int err = 0;
 
 	spin_lock_bh(&enic->devcmd_lock);
-	err = vnic_dev_enable_wait(enic->vdev);
+	if (enic->enable_count == 0)
+		err = vnic_dev_enable_wait(enic->vdev);
+	if (!err)
+		enic->enable_count++;
 	spin_unlock_bh(&enic->devcmd_lock);
 
 	return err;
@@ -142,10 +145,16 @@ int enic_dev_enable(struct enic *enic)
 
 int enic_dev_disable(struct enic *enic)
 {
-	int err;
+	int err = 0;
 
 	spin_lock_bh(&enic->devcmd_lock);
-	err = vnic_dev_disable(enic->vdev);
+	if (enic->enable_count == 0) {
+		spin_unlock_bh(&enic->devcmd_lock);
+		return 0;
+	}
+	enic->enable_count--;
+	if (enic->enable_count == 0)
+		err = vnic_dev_disable(enic->vdev);
 	spin_unlock_bh(&enic->devcmd_lock);
 
 	return err;

-- 
2.43.0