linux-kernel - [PATCH 087/117] Staging: hv: storvsc: Further cleanup reference counting of stor

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Date:	Fri, 15 Jul 2011 10:47:15 -0700
From:	"K. Y. Srinivasan" <kys@...rosoft.com>
To:	gregkh@...e.de, linux-kernel@...r.kernel.org,
	devel@...uxdriverproject.org, virtualization@...ts.osdl.org
Cc:	"K. Y. Srinivasan" <kys@...rosoft.com>,
	Haiyang Zhang <haiyangz@...rosoft.com>
Subject: [PATCH 087/117] Staging: hv: storvsc: Further cleanup reference counting of stor_device

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@...rosoft.com>
Signed-off-by: Haiyang Zhang <haiyangz@...rosoft.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

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