[PATCH] Drivers: hv: vmbus: fix init_vp_index() for reloading hv_netvsc

From: Dexuan Cui <decui@microsoft.com>
To: gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org,
	driverdev-devel@linuxdriverproject.org, olaf@aepfle.de,
	apw@canonical.com, jasowang@redhat.com, kys@microsoft.com
Subject: [PATCH] Drivers: hv: vmbus: fix init_vp_index() for reloading hv_netvsc
Date: Wed, 12 Aug 2015 06:48:46 -0700	[thread overview]
Message-ID: <1439387326-32427-1-git-send-email-decui@microsoft.com> (raw)

This fixes the recent commit:
Drivers: hv: vmbus: Further improve CPU affiliation logic

Without the fix, reloading hv_netvsc hangs the guest.

Signed-off-by: Dexuan Cui <decui@microsoft.com>
---
 drivers/hv/channel_mgmt.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index 2f9aead..f61bd07 100644
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -458,6 +458,19 @@ static void init_vp_index(struct vmbus_channel *channel, const uuid_le *type_gui
 			continue;
 		}
 
+		if (cpumask_weight(&primary->alloced_cpus_in_node) ==
+		    cpumask_weight(cpumask_of_node(primary->numa_node))) {
+			/*
+			 * We have cycled through all the CPUs in the node;
+			 * reset the alloced map.
+			 * This is necessary because we never clear
+			 * primary->alloced_cpus_in_node in other places.
+			 * We need this to "break" the loop when reloading
+			 * hv_netvsc in SMP guest.
+			 */
+			cpumask_clear(&primary->alloced_cpus_in_node);
+		}
+
 		if (!cpumask_test_cpu(cur_cpu,
 				&primary->alloced_cpus_in_node)) {
 			cpumask_set_cpu(cur_cpu,
-- 
2.1.0

