[kernel/f13/master] add virtio_net-add-schedule-check-to-napi_enable-call.patch

[Kyle McMartin]

commit 7adc359067081518dc323419172855e37f227652
Author: Kyle McMartin <kyle at redhat.com>
Date:   Wed Mar 23 11:35:44 2011 -0400

    add virtio_net-add-schedule-check-to-napi_enable-call.patch

 kernel.spec                                        |    7 ++
 ...et-add-schedule-check-to-napi_enable-call.patch |   76 ++++++++++++++++++++
 2 files changed, 83 insertions(+), 0 deletions(-)
---
diff --git a/kernel.spec b/kernel.spec
index ee16085..d1e94e0 100644
--- a/kernel.spec
+++ b/kernel.spec
@@ -891,6 +891,8 @@ Patch13951: bridge-fix-mglist-corruption-that-leads-to-memory-corruption.patch
 # rhbz#649871
 Patch13952: drm-hold-the-mutex-when-dropping-the-last-gem-reference-v2.patch
 
+Patch13955: virtio_net-add-schedule-check-to-napi_enable-call.patch
+
 %endif
 
 BuildRoot: %{_tmppath}/kernel-%{KVERREL}-root
@@ -1694,6 +1696,8 @@ ApplyPatch bridge-fix-mglist-corruption-that-leads-to-memory-corruption.patch
 # rhbz#649871
 ApplyPatch drm-hold-the-mutex-when-dropping-the-last-gem-reference-v2.patch
 
+ApplyPatch virtio_net-add-schedule-check-to-napi_enable-call.patch
+
 # END OF PATCH APPLICATIONS
 
 %endif
@@ -2314,6 +2318,9 @@ fi
 %kernel_variant_files %{with_pae_debug} PAEdebug
 
 %changelog
+* Wed Mar 23 2011 Kyle McMartin <kmcmartin at redhat.com>
+- Backport 3e9d08e: "virtio_net: Add schedule check to napi_enable call"
+
 * Fri Mar 11 2011 Chuck Ebbert <cebbert at redhat.com>
 - Drop linux-2.6-defaults-aspm.patch; fixing ASPM properly will
   be too difficult in this old kernel.
diff --git a/virtio_net-add-schedule-check-to-napi_enable-call.patch b/virtio_net-add-schedule-check-to-napi_enable-call.patch
new file mode 100644
index 0000000..743c410
--- /dev/null
+++ b/virtio_net-add-schedule-check-to-napi_enable-call.patch
@@ -0,0 +1,76 @@
+From 0d043d4e014306398b5aae1aebbeb9c258e2d5f1 Mon Sep 17 00:00:00 2001
+From: Bruce Rogers <brogers at novell.com>
+Date: Thu, 10 Feb 2011 11:03:31 -0800
+Subject: [PATCH] virtio_net: Add schedule check to napi_enable call
+
+Under harsh testing conditions, including low memory, the guest would
+stop receiving packets. With this patch applied we no longer see any
+problems in the driver while performing these tests for extended periods
+of time.
+
+Make sure napi is scheduled subsequent to each napi_enable.
+
+Signed-off-by: Bruce Rogers <brogers at novell.com>
+Signed-off-by: Olaf Kirch <okir at suse.de>
+Cc: stable at kernel.org
+Signed-off-by: Rusty Russell <rusty at rustcorp.com.au>
+Signed-off-by: David S. Miller <davem at davemloft.net>
+---
+ drivers/net/virtio_net.c |   27 ++++++++++++++++-----------
+ 1 files changed, 16 insertions(+), 11 deletions(-)
+
+diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
+index f5b5d74..195104d 100644
+--- a/drivers/net/virtio_net.c
++++ b/drivers/net/virtio_net.c
+@@ -448,6 +448,20 @@ static void skb_recv_done(struct virtqueue *rvq)
+ 	}
+ }
+ 
++static void virtnet_napi_enable(struct virtnet_info *vi)
++{
++	napi_enable(&vi->napi);
++
++	/* If all buffers were filled by other side before we napi_enabled, we
++	 * won't get another interrupt, so process any outstanding packets
++	 * now.  virtnet_poll wants re-enable the queue, so we disable here.
++	 * We synchronize against interrupts via NAPI_STATE_SCHED */
++	if (napi_schedule_prep(&vi->napi)) {
++		virtqueue_disable_cb(vi->rvq);
++		__napi_schedule(&vi->napi);
++	}
++}
++
+ static void refill_work(struct work_struct *work)
+ {
+ 	struct virtnet_info *vi;
+@@ -456,7 +470,7 @@ static void refill_work(struct work_struct *work)
+ 	vi = container_of(work, struct virtnet_info, refill.work);
+ 	napi_disable(&vi->napi);
+ 	still_empty = !try_fill_recv(vi, GFP_KERNEL);
+-	napi_enable(&vi->napi);
++	virtnet_napi_enable(vi);
+ 
+ 	/* In theory, this can happen: if we don't get any buffers in
+ 	 * we will *never* try to fill again. */
+@@ -642,16 +656,7 @@ static int virtnet_open(struct net_device *dev)
+ {
+ 	struct virtnet_info *vi = netdev_priv(dev);
+ 
+-	napi_enable(&vi->napi);
+-
+-	/* If all buffers were filled by other side before we napi_enabled, we
+-	 * won't get another interrupt, so process any outstanding packets
+-	 * now.  virtnet_poll wants re-enable the queue, so we disable here.
+-	 * We synchronize against interrupts via NAPI_STATE_SCHED */
+-	if (napi_schedule_prep(&vi->napi)) {
+-		virtqueue_disable_cb(vi->rvq);
+-		__napi_schedule(&vi->napi);
+-	}
++	virtnet_napi_enable(vi);
+ 	return 0;
+ }
+ 
+-- 
+1.7.4.1
+