[PATCH 1/3] staging: hv: convert VmbusOnMsgDPC to not call osd_schedule_callback

[Timo Teräs]

The additional abstraction is unneeded. This also fixes a sleeping
while atomic issue as osd_schedule_callback can sleep which is
not allowed for VmbusOnMsgDPC running in a tasklet.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=16701
Cc: Haiyang Zhang <haiyangz at microsoft.com>
Cc: Hank Janssen <hjanssen at microsoft.com>
Signed-off-by: Timo Teräs <timo.teras at iki.fi>
---
 drivers/staging/hv/channel_mgmt.c |    4 ----
 drivers/staging/hv/vmbus.c        |   27 +++++++++++++++++++++------
 2 files changed, 21 insertions(+), 10 deletions(-)

diff --git a/drivers/staging/hv/channel_mgmt.c b/drivers/staging/hv/channel_mgmt.c
index 45dbe30..07806a3 100644
--- a/drivers/staging/hv/channel_mgmt.c
+++ b/drivers/staging/hv/channel_mgmt.c
@@ -753,7 +753,6 @@ void vmbus_onmessage(void *context)
 			   hdr->MessageType, size);
 		print_hex_dump_bytes("", DUMP_PREFIX_NONE,
 				     (unsigned char *)msg->u.Payload, size);
-		kfree(msg);
 		return;
 	}
 
@@ -762,9 +761,6 @@ void vmbus_onmessage(void *context)
 	else
 		DPRINT_ERR(VMBUS, "Unhandled channel message type %d",
 			   hdr->MessageType);
-
-	/* Free the msg that was allocated in VmbusOnMsgDPC() */
-	kfree(msg);
 }
 
 /*
diff --git a/drivers/staging/hv/vmbus.c b/drivers/staging/hv/vmbus.c
index d449daf..8607046 100644
--- a/drivers/staging/hv/vmbus.c
+++ b/drivers/staging/hv/vmbus.c
@@ -141,6 +141,21 @@ static void VmbusOnCleanup(struct hv_driver *drv)
 	HvCleanup();
 }
 
+struct onmessage_work_context {
+	struct work_struct work;
+	struct hv_message msg;
+};
+
+static void vmbus_onmessage_work(struct work_struct *work)
+{
+	struct onmessage_work_context *ctx;
+
+	ctx = container_of(work, struct onmessage_work_context,
+			   work);
+	vmbus_onmessage(&ctx->msg);
+	kfree(ctx);
+}
+
 /*
  * VmbusOnMsgDPC - DPC routine to handle messages from the hypervisior
  */
@@ -150,20 +165,20 @@ static void VmbusOnMsgDPC(struct hv_driver *drv)
 	void *page_addr = gHvContext.synICMessagePage[cpu];
 	struct hv_message *msg = (struct hv_message *)page_addr +
 				  VMBUS_MESSAGE_SINT;
-	struct hv_message *copied;
+	struct onmessage_work_context *ctx;
 
 	while (1) {
 		if (msg->Header.MessageType == HvMessageTypeNone) {
 			/* no msg */
 			break;
 		} else {
-			copied = kmemdup(msg, sizeof(*copied), GFP_ATOMIC);
-			if (copied == NULL)
+			ctx = kmalloc(sizeof(*ctx), GFP_ATOMIC);
+			if (ctx == NULL)
 				continue;
 
-			osd_schedule_callback(gVmbusConnection.WorkQueue,
-					      vmbus_onmessage,
-					      (void *)copied);
+			INIT_WORK(&ctx->work, vmbus_onmessage_work);
+			memcpy(&ctx->msg, msg, sizeof(*msg));
+			queue_work(gVmbusConnection.WorkQueue, &ctx->work);
 		}
 
 		msg->Header.MessageType = HvMessageTypeNone;
-- 
1.7.1