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Date:      Mon, 16 May 2016 03:56:25 +0000 (UTC)
From:      Sepherosa Ziehau <sephe@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r299890 - head/sys/dev/hyperv/vmbus
Message-ID:  <201605160356.u4G3uPIJ013926@repo.freebsd.org>
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Author: sephe
Date: Mon May 16 03:56:24 2016
New Revision: 299890
URL: https://svnweb.freebsd.org/changeset/base/299890

Log:
  hyperv/vmbus: Simplify event processing
  
  For channel0, it will never be processed on event handling path,
  so there is no need to install it.  After skipping in the channel0
  installation, we could discard the channel0 check on event
  handling hot code path.
  
  MFC after:	1 week
  Sponsored by:	Microsoft OSTC
  Differential Revision:	https://reviews.freebsd.org/D6333

Modified:
  head/sys/dev/hyperv/vmbus/hv_channel_mgmt.c
  head/sys/dev/hyperv/vmbus/hv_connection.c

Modified: head/sys/dev/hyperv/vmbus/hv_channel_mgmt.c
==============================================================================
--- head/sys/dev/hyperv/vmbus/hv_channel_mgmt.c	Mon May 16 03:48:00 2016	(r299889)
+++ head/sys/dev/hyperv/vmbus/hv_channel_mgmt.c	Mon May 16 03:56:24 2016	(r299890)
@@ -183,7 +183,14 @@ vmbus_channel_process_offer(hv_vmbus_cha
 	 * Make sure this is a new offer
 	 */
 	mtx_lock(&hv_vmbus_g_connection.channel_lock);
-	hv_vmbus_g_connection.channels[relid] = new_channel;
+	if (relid == 0) {
+		/*
+		 * XXX channel0 will not be processed; skip it.
+		 */
+		printf("VMBUS: got channel0 offer\n");
+	} else {
+		hv_vmbus_g_connection.channels[relid] = new_channel;
+	}
 
 	TAILQ_FOREACH(channel, &hv_vmbus_g_connection.channel_anchor,
 	    list_entry) {

Modified: head/sys/dev/hyperv/vmbus/hv_connection.c
==============================================================================
--- head/sys/dev/hyperv/vmbus/hv_connection.c	Mon May 16 03:48:00 2016	(r299889)
+++ head/sys/dev/hyperv/vmbus/hv_connection.c	Mon May 16 03:56:24 2016	(r299890)
@@ -337,15 +337,11 @@ hv_vmbus_on_events(int cpu)
 	        for (bit = 0; bit < HV_CHANNEL_DWORD_LEN; bit++) {
 	    	if (synch_test_and_clear_bit(bit,
 	    	    (uint32_t *) &recv_interrupt_page[dword])) {
-	    	    rel_id = (dword << 5) + bit;
-	    	    if (rel_id == 0) {
-	    		/*
-	    		 * Special case -
-	    		 * vmbus channel protocol msg.
-	    		 */
-	    		continue;
-	    	    } else {
-	    		hv_vmbus_channel * channel = hv_vmbus_g_connection.channels[rel_id];
+			struct hv_vmbus_channel *channel;
+
+			rel_id = (dword << 5) + bit;
+	    		channel = hv_vmbus_g_connection.channels[rel_id];
+
 	    		/* if channel is closed or closing */
 	    		if (channel == NULL || channel->rxq == NULL)
 	    			continue;
@@ -353,7 +349,6 @@ hv_vmbus_on_events(int cpu)
 	    		if (channel->batched_reading)
 	    			hv_ring_buffer_read_begin(&channel->inbound);
 	    		taskqueue_enqueue(channel->rxq, &channel->channel_task);
-	    	    }
 	    	}
 	        }
 	    }

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