[PATCH 087/117] Staging: hv: storvsc: Further cleanup reference counting of stor_device

K. Y. Srinivasan
2011-07-15T17:36:10Z

Further cleanup reference counting of stor_device - when the device is being
destroyed, we will permit incoming traffic only to drain outstanding
requests.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
---
drivers/staging/hv/hyperv_storage.h | 3 +--
drivers/staging/hv/storvsc.c | 22 +++++++++++++---------
2 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/drivers/staging/hv/hyperv_storage.h b/drivers/staging/hv/hyperv_storage.h
index d946211..a1f3e27 100644
--- a/drivers/staging/hv/hyperv_storage.h
+++ b/drivers/staging/hv/hyperv_storage.h
@@ -287,7 +287,6 @@ struct storvsc_device {
};

-/* Get the stordevice object iff exists and its refcount > 1 */
static inline struct storvsc_device *get_out_stor_device(
struct hv_device *device)
{
@@ -296,7 +295,7 @@ static inline struct storvsc_device *get_out_stor_device(

spin_lock_irqsave(&device->ext_lock, flags);
stor_device = (struct storvsc_device *)device->ext;
- if (stor_device && (stor_device->ref_count > 1) &&
+ if (stor_device && (stor_device->ref_count) &&
!stor_device->destroy)
stor_device->ref_count++;
else
diff --git a/drivers/staging/hv/storvsc.c b/drivers/staging/hv/storvsc.c
index a41be2a..4d13044 100644
--- a/drivers/staging/hv/storvsc.c
+++ b/drivers/staging/hv/storvsc.c
@@ -40,9 +40,7 @@ static inline struct storvsc_device *alloc_stor_device(struct hv_device *device)
if (!stor_device)
return NULL;

- /* Set to 2 to allow both inbound and outbound traffics */
- /* (ie get_out_stor_device() and get_in_stor_device()) to proceed. */
- stor_device->ref_count = 2;
+ stor_device->ref_count = 1;
stor_device->destroy = false;
init_waitqueue_head(&stor_device->waiting_to_drain);
stor_device->device = device;
@@ -51,8 +49,6 @@ static inline struct storvsc_device *alloc_stor_device(struct hv_device *device)
return stor_device;
}

-
-/* Get the stordevice object iff exists and its refcount > 0 */
static inline struct storvsc_device *get_in_stor_device(
struct hv_device *device)
{
@@ -61,10 +57,18 @@ static inline struct storvsc_device *get_in_stor_device(

spin_lock_irqsave(&device->ext_lock, flags);
stor_device = (struct storvsc_device *)device->ext;
- if (stor_device && stor_device->ref_count)
- stor_device->ref_count++;
- else
- stor_device = NULL;
+ if (!stor_device)
+ goto cleanup;
+
+ /*
+ * If the device is being destroyed; allow incoming
+ * traffic only to cleanup outstanding requests.
+ */
+ if (stor_device->destroy &&
+ (atomic_read(&stor_device->num_outstanding_req) == 0))
+ goto cleanup;
+ stor_device->ref_count++;
+cleanup:
spin_unlock_irqrestore(&device->ext_lock, flags);

return stor_device;
--
1.7.4.1