[PATCH 096/117] Staging: hv: netvsc: Further cleanup reference counting of netvsc_device

K. Y. Srinivasan
2011-07-15T17:36:12Z

Further cleanup reference counting of netvsc_device. Since once the device
is marked for destruction, we only allow incoming traffic to drain out
outstanding sends, we can simplify reference counting.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
---
drivers/staging/hv/netvsc.c | 27 ++++++++++++++++++---------
1 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/drivers/staging/hv/netvsc.c b/drivers/staging/hv/netvsc.c
index 4ef17d8..16a80b1 100644
--- a/drivers/staging/hv/netvsc.c
+++ b/drivers/staging/hv/netvsc.c
@@ -17,6 +17,7 @@
* Authors:
* Haiyang Zhang <haiyangz@microsoft.com>
* Hank Janssen <hjanssen@microsoft.com>
+ * K. Y. Srinivasan <kys@microsoft.com>
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

@@ -40,8 +41,7 @@ static struct netvsc_device *alloc_net_device(struct hv_device *device)
if (!net_device)
return NULL;

- /* Set to 2 to allow both inbound and outbound traffic */
- net_device->refcnt = 2;
+ net_device->refcnt = 1;

net_device->destroy = false;
net_device->dev = device;
@@ -50,7 +50,6 @@ static struct netvsc_device *alloc_net_device(struct hv_device *device)
return net_device;
}

-/* Get the net device object iff exists and its refcount > 1 */
static struct netvsc_device *get_outbound_net_device(struct hv_device *device)
{
struct netvsc_device *net_device;
@@ -58,7 +57,7 @@ static struct netvsc_device *get_outbound_net_device(struct hv_device *device)

spin_lock_irqsave(&device->ext_lock, flags);
net_device = device->ext;
- if (net_device && (net_device->refcnt > 1) &&
+ if (net_device && (net_device->refcnt) &&
!net_device->destroy)
net_device->refcnt++;
else
@@ -68,7 +67,6 @@ static struct netvsc_device *get_outbound_net_device(struct hv_device *device)
return net_device;
}

-/* Get the net device object iff exists and its refcount > 0 */
static struct netvsc_device *get_inbound_net_device(struct hv_device *device)
{
struct netvsc_device *net_device;
@@ -76,11 +74,23 @@ static struct netvsc_device *get_inbound_net_device(struct hv_device *device)

spin_lock_irqsave(&device->ext_lock, flags);
net_device = device->ext;
- if (net_device && net_device->refcnt)
- net_device->refcnt++;
- else
+
+ if (!net_device)
+ goto cleanup;
+
+ /*
+ * If the device is being destroyed; allow incoming
+ * traffic only to cleanup outstanding requests.
+ */
+ if (net_device->destroy &&
+ (atomic_read(&net_device->num_outstanding_sends) == 0)) {
net_device = NULL;
+ goto cleanup;
+ }

+ net_device->refcnt++;
+
+cleanup:
spin_unlock_irqrestore(&device->ext_lock, flags);
return net_device;
}
@@ -400,7 +410,6 @@ int netvsc_device_remove(struct hv_device *device)
netvsc_disconnect_vsp(net_device);

spin_lock_irqsave(&device->ext_lock, flags);
- net_device->refcnt--;
device->ext = NULL;
spin_unlock_irqrestore(&device->ext_lock, flags);

--
1.7.4.1