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Subject[PATCH 5.0 006/117] hv_netvsc: Fix unwanted wakeup after tx_disable
Date
[ Upstream commit 1b704c4a1ba95574832e730f23817b651db2aa59 ]

After queue stopped, the wakeup mechanism may wake it up again
when ring buffer usage is lower than a threshold. This may cause
send path panic on NULL pointer when we stopped all tx queues in
netvsc_detach and start removing the netvsc device.

This patch fix it by adding a tx_disable flag to prevent unwanted
queue wakeup.

Fixes: 7b2ee50c0cd5 ("hv_netvsc: common detach logic")
Reported-by: Mohammed Gamal <mgamal@redhat.com>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/hyperv/hyperv_net.h | 1 +
drivers/net/hyperv/netvsc.c | 6 ++++--
drivers/net/hyperv/netvsc_drv.c | 32 ++++++++++++++++++++++++++------
3 files changed, 31 insertions(+), 8 deletions(-)

diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
index e859ae2e42d5..49f41b64077b 100644
--- a/drivers/net/hyperv/hyperv_net.h
+++ b/drivers/net/hyperv/hyperv_net.h
@@ -987,6 +987,7 @@ struct netvsc_device {

wait_queue_head_t wait_drain;
bool destroy;
+ bool tx_disable; /* if true, do not wake up queue again */

/* Receive buffer allocated by us but manages by NetVSP */
void *recv_buf;
diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
index 813d195bbd57..e0dce373cdd9 100644
--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -110,6 +110,7 @@ static struct netvsc_device *alloc_net_device(void)

init_waitqueue_head(&net_device->wait_drain);
net_device->destroy = false;
+ net_device->tx_disable = false;

net_device->max_pkt = RNDIS_MAX_PKT_DEFAULT;
net_device->pkt_align = RNDIS_PKT_ALIGN_DEFAULT;
@@ -719,7 +720,7 @@ static void netvsc_send_tx_complete(struct net_device *ndev,
} else {
struct netdev_queue *txq = netdev_get_tx_queue(ndev, q_idx);

- if (netif_tx_queue_stopped(txq) &&
+ if (netif_tx_queue_stopped(txq) && !net_device->tx_disable &&
(hv_get_avail_to_write_percent(&channel->outbound) >
RING_AVAIL_PERCENT_HIWATER || queue_sends < 1)) {
netif_tx_wake_queue(txq);
@@ -874,7 +875,8 @@ static inline int netvsc_send_pkt(
} else if (ret == -EAGAIN) {
netif_tx_stop_queue(txq);
ndev_ctx->eth_stats.stop_queue++;
- if (atomic_read(&nvchan->queue_sends) < 1) {
+ if (atomic_read(&nvchan->queue_sends) < 1 &&
+ !net_device->tx_disable) {
netif_tx_wake_queue(txq);
ndev_ctx->eth_stats.wake_queue++;
ret = -ENOSPC;
diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index cf4897043e83..b20fb0fb595b 100644
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -109,6 +109,15 @@ static void netvsc_set_rx_mode(struct net_device *net)
rcu_read_unlock();
}

+static void netvsc_tx_enable(struct netvsc_device *nvscdev,
+ struct net_device *ndev)
+{
+ nvscdev->tx_disable = false;
+ virt_wmb(); /* ensure queue wake up mechanism is on */
+
+ netif_tx_wake_all_queues(ndev);
+}
+
static int netvsc_open(struct net_device *net)
{
struct net_device_context *ndev_ctx = netdev_priv(net);
@@ -129,7 +138,7 @@ static int netvsc_open(struct net_device *net)
rdev = nvdev->extension;
if (!rdev->link_state) {
netif_carrier_on(net);
- netif_tx_wake_all_queues(net);
+ netvsc_tx_enable(nvdev, net);
}

if (vf_netdev) {
@@ -184,6 +193,17 @@ static int netvsc_wait_until_empty(struct netvsc_device *nvdev)
}
}

+static void netvsc_tx_disable(struct netvsc_device *nvscdev,
+ struct net_device *ndev)
+{
+ if (nvscdev) {
+ nvscdev->tx_disable = true;
+ virt_wmb(); /* ensure txq will not wake up after stop */
+ }
+
+ netif_tx_disable(ndev);
+}
+
static int netvsc_close(struct net_device *net)
{
struct net_device_context *net_device_ctx = netdev_priv(net);
@@ -192,7 +212,7 @@ static int netvsc_close(struct net_device *net)
struct netvsc_device *nvdev = rtnl_dereference(net_device_ctx->nvdev);
int ret;

- netif_tx_disable(net);
+ netvsc_tx_disable(nvdev, net);

/* No need to close rndis filter if it is removed already */
if (!nvdev)
@@ -920,7 +940,7 @@ static int netvsc_detach(struct net_device *ndev,

/* If device was up (receiving) then shutdown */
if (netif_running(ndev)) {
- netif_tx_disable(ndev);
+ netvsc_tx_disable(nvdev, ndev);

ret = rndis_filter_close(nvdev);
if (ret) {
@@ -1908,7 +1928,7 @@ static void netvsc_link_change(struct work_struct *w)
if (rdev->link_state) {
rdev->link_state = false;
netif_carrier_on(net);
- netif_tx_wake_all_queues(net);
+ netvsc_tx_enable(net_device, net);
} else {
notify = true;
}
@@ -1918,7 +1938,7 @@ static void netvsc_link_change(struct work_struct *w)
if (!rdev->link_state) {
rdev->link_state = true;
netif_carrier_off(net);
- netif_tx_stop_all_queues(net);
+ netvsc_tx_disable(net_device, net);
}
kfree(event);
break;
@@ -1927,7 +1947,7 @@ static void netvsc_link_change(struct work_struct *w)
if (!rdev->link_state) {
rdev->link_state = true;
netif_carrier_off(net);
- netif_tx_stop_all_queues(net);
+ netvsc_tx_disable(net_device, net);
event->event = RNDIS_STATUS_MEDIA_CONNECT;
spin_lock_irqsave(&ndev_ctx->lock, flags);
list_add(&event->list, &ndev_ctx->reconfig_events);
--
2.19.1


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