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Groups > linux.kernel > #1332822

[PATCH 3/4] Drivers: hv: vmbus: remove code duplication in message handling

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We have 3 functions dealing with messages and they all implement
the same logic to finalize reads, move it to vmbus_signal_eom().

Suggested-by: Radim Krcmar <rkrcmar@redhat.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
 drivers/hv/channel_mgmt.c | 10 +---------
 drivers/hv/hyperv_vmbus.h | 24 ++++++++++++++++++++++++
 drivers/hv/vmbus_drv.c    | 40 ++--------------------------------------
 3 files changed, 27 insertions(+), 47 deletions(-)

diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index bd60207..1e43967 100644
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -529,15 +529,7 @@ static void vmbus_wait_for_unload(void)
 		if (hdr->msgtype == CHANNELMSG_UNLOAD_RESPONSE)
 			unloaded = true;
 
-		msg->header.message_type = HVMSG_NONE;
-		/*
-		 * header.message_type needs to be written before we do
-		 * wrmsrl() below.
-		 */
-		mb();
-
-		if (msg->header.message_flags.msg_pending)
-			wrmsrl(HV_X64_MSR_EOM, 0);
+		vmbus_signal_eom(msg);
 
 		if (unloaded)
 			break;
diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index e6160a0..86049a3 100644
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -626,6 +626,30 @@ struct vmbus_channel_message_table_entry {
 extern struct vmbus_channel_message_table_entry
 	channel_message_table[CHANNELMSG_COUNT];
 
+/* Free the message slot and signal end-of-message if required */
+static inline void vmbus_signal_eom(struct hv_message *msg)
+{
+	msg->header.message_type = HVMSG_NONE;
+
+	/*
+	 * Make sure the write to MessageType (ie set to
+	 * HVMSG_NONE) happens before we read the
+	 * MessagePending and EOMing. Otherwise, the EOMing
+	 * will not deliver any more messages since there is
+	 * no empty slot
+	 */
+	mb();
+
+	if (msg->header.message_flags.msg_pending) {
+		/*
+		 * This will cause message queue rescan to
+		 * possibly deliver another msg from the
+		 * hypervisor
+		 */
+		wrmsrl(HV_X64_MSR_EOM, 0);
+	}
+}
+
 /* General vmbus interface */
 
 struct hv_device *vmbus_device_create(const uuid_le *type,
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 08f98a1..c9204c0 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -685,25 +685,7 @@ static void hv_process_timer_expiration(struct hv_message *msg, int cpu)
 	if (dev->event_handler)
 		dev->event_handler(dev);
 
-	msg->header.message_type = HVMSG_NONE;
-
-	/*
-	 * Make sure the write to MessageType (ie set to
-	 * HVMSG_NONE) happens before we read the
-	 * MessagePending and EOMing. Otherwise, the EOMing
-	 * will not deliver any more messages since there is
-	 * no empty slot
-	 */
-	mb();
-
-	if (msg->header.message_flags.msg_pending) {
-		/*
-		 * This will cause message queue rescan to
-		 * possibly deliver another msg from the
-		 * hypervisor
-		 */
-		wrmsrl(HV_X64_MSR_EOM, 0);
-	}
+	vmbus_signal_eom(msg);
 }
 
 static void vmbus_on_msg_dpc(unsigned long data)
@@ -741,25 +723,7 @@ static void vmbus_on_msg_dpc(unsigned long data)
 		entry->message_handler(hdr);
 
 msg_handled:
-	msg->header.message_type = HVMSG_NONE;
-
-	/*
-	 * Make sure the write to MessageType (ie set to
-	 * HVMSG_NONE) happens before we read the
-	 * MessagePending and EOMing. Otherwise, the EOMing
-	 * will not deliver any more messages since there is
-	 * no empty slot
-	 */
-	mb();
-
-	if (msg->header.message_flags.msg_pending) {
-		/*
-		 * This will cause message queue rescan to
-		 * possibly deliver another msg from the
-		 * hypervisor
-		 */
-		wrmsrl(HV_X64_MSR_EOM, 0);
-	}
+	vmbus_signal_eom(msg);
 }
 
 static void vmbus_isr(void)
-- 
2.5.0

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[PATCH 0/4] Drivers: hv: vmbus: bugfix and improvements for message handling Vitaly Kuznetsov <vkuznets@redhat.com> - 2016-02-12 16:50 +0100
  [PATCH 1/4] Drivers: hv: vmbus: don't loose HVMSG_TIMER_EXPIRED messages Vitaly Kuznetsov <vkuznets@redhat.com> - 2016-02-12 16:50 +0100
    Re: [PATCH 1/4] Drivers: hv: vmbus: don't loose HVMSG_TIMER_EXPIRED  messages Radim Krcmar <rkrcmar@redhat.com> - 2016-02-15 22:00 +0100
  [PATCH 2/4] Drivers: hv: vmbus: avoid wait_for_completion() on crash Vitaly Kuznetsov <vkuznets@redhat.com> - 2016-02-12 16:50 +0100
    Re: [PATCH 2/4] Drivers: hv: vmbus: avoid wait_for_completion() on  crash Radim Krcmar <rkrcmar@redhat.com> - 2016-02-15 22:10 +0100
  [PATCH 3/4] Drivers: hv: vmbus: remove code duplication in message handling Vitaly Kuznetsov <vkuznets@redhat.com> - 2016-02-12 16:50 +0100
    Re: [PATCH 3/4] Drivers: hv: vmbus: remove code duplication in  message handling Radim Krcmar <rkrcmar@redhat.com> - 2016-02-15 22:10 +0100
  [PATCH 4/4] Drivers: hv: vmbus: avoid unneeded compiler optimizations in vmbus_wait_for_unload() Vitaly Kuznetsov <vkuznets@redhat.com> - 2016-02-12 16:50 +0100
    Re: [PATCH 4/4] Drivers: hv: vmbus: avoid unneeded compiler  optimizations in vmbus_wait_for_unload() Radim Krcmar <rkrcmar@redhat.com> - 2016-02-15 22:20 +0100

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