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Subject[PATCH 17/40] Staging: hv: netvsc: Use the newly introduced lock in accessing ext field
Date
The current reference counting mechanism is broken; use the newly introduced
lock to access the net_device pointer in struct hv_device.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Abhishek Kane <v-abkane@microsoft.com>
Signed-off-by: Hank Janssen <hjanssen@microsoft.com>
---
drivers/staging/hv/netvsc.c | 24 ++++++++++++++++++++++--
1 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/hv/netvsc.c b/drivers/staging/hv/netvsc.c
index f03018c..531de63 100644
--- a/drivers/staging/hv/netvsc.c
+++ b/drivers/staging/hv/netvsc.c
@@ -56,12 +56,15 @@ static struct netvsc_device *alloc_net_device(struct hv_device *device)
static struct netvsc_device *get_outbound_net_device(struct hv_device *device)
{
struct netvsc_device *net_device;
+ unsigned long flags;

+ spin_lock_irqsave(&device->ext_lock, flags);
net_device = device->ext;
if (net_device && atomic_read(&net_device->refcnt) > 1)
atomic_inc(&net_device->refcnt);
else
net_device = NULL;
+ spin_unlock_irqrestore(&device->ext_lock, flags);

return net_device;
}
@@ -70,38 +73,50 @@ static struct netvsc_device *get_outbound_net_device(struct hv_device *device)
static struct netvsc_device *get_inbound_net_device(struct hv_device *device)
{
struct netvsc_device *net_device;
+ unsigned long flags;

+ spin_lock_irqsave(&device->ext_lock, flags);
net_device = device->ext;
if (net_device && atomic_read(&net_device->refcnt))
atomic_inc(&net_device->refcnt);
else
net_device = NULL;

+ spin_unlock_irqrestore(&device->ext_lock, flags);
return net_device;
}

static void put_net_device(struct hv_device *device)
{
struct netvsc_device *net_device;
+ unsigned long flags;
+
+ spin_lock_irqsave(&device->ext_lock, flags);

net_device = device->ext;

atomic_dec(&net_device->refcnt);
+ spin_unlock_irqrestore(&device->ext_lock, flags);
}

static struct netvsc_device *release_outbound_net_device(
struct hv_device *device)
{
struct netvsc_device *net_device;
+ unsigned long flags;

+ spin_lock_irqsave(&device->ext_lock, flags);
net_device = device->ext;
- if (net_device == NULL)
+ if (net_device == NULL) {
+ spin_unlock_irqrestore(&device->ext_lock, flags);
return NULL;
+ }

/* Busy wait until the ref drop to 2, then set it to 1 */
while (atomic_cmpxchg(&net_device->refcnt, 2, 1) != 2)
udelay(100);

+ spin_unlock_irqrestore(&device->ext_lock, flags);
return net_device;
}

@@ -109,16 +124,21 @@ static struct netvsc_device *release_inbound_net_device(
struct hv_device *device)
{
struct netvsc_device *net_device;
+ unsigned long flags;

+ spin_lock_irqsave(&device->ext_lock, flags);
net_device = device->ext;
- if (net_device == NULL)
+ if (net_device == NULL) {
+ spin_unlock_irqrestore(&device->ext_lock, flags);
return NULL;
+ }

/* Busy wait until the ref drop to 1, then set it to 0 */
while (atomic_cmpxchg(&net_device->refcnt, 1, 0) != 1)
udelay(100);

device->ext = NULL;
+ spin_unlock_irqrestore(&device->ext_lock, flags);
return net_device;
}

--
1.7.4.1


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