ASR_BASE
Change-Id: Icf3719cc0afe3eeb3edc7fa80a2eb5199ca9dda1
diff --git a/target/linux/generic/backport-5.4/602-v5.12-net-add-sysfs-attribute-to-control-napi-threaded-mod.patch b/target/linux/generic/backport-5.4/602-v5.12-net-add-sysfs-attribute-to-control-napi-threaded-mod.patch
new file mode 100644
index 0000000..05c40a9
--- /dev/null
+++ b/target/linux/generic/backport-5.4/602-v5.12-net-add-sysfs-attribute-to-control-napi-threaded-mod.patch
@@ -0,0 +1,177 @@
+From: Wei Wang <weiwan@google.com>
+Date: Mon, 8 Feb 2021 11:34:10 -0800
+Subject: [PATCH] net: add sysfs attribute to control napi threaded mode
+
+This patch adds a new sysfs attribute to the network device class.
+Said attribute provides a per-device control to enable/disable the
+threaded mode for all the napi instances of the given network device,
+without the need for a device up/down.
+User sets it to 1 or 0 to enable or disable threaded mode.
+Note: when switching between threaded and the current softirq based mode
+for a napi instance, it will not immediately take effect if the napi is
+currently being polled. The mode switch will happen for the next time
+napi_schedule() is called.
+
+Co-developed-by: Paolo Abeni <pabeni@redhat.com>
+Signed-off-by: Paolo Abeni <pabeni@redhat.com>
+Co-developed-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
+Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
+Co-developed-by: Felix Fietkau <nbd@nbd.name>
+Signed-off-by: Felix Fietkau <nbd@nbd.name>
+Signed-off-by: Wei Wang <weiwan@google.com>
+Reviewed-by: Alexander Duyck <alexanderduyck@fb.com>
+Signed-off-by: David S. Miller <davem@davemloft.net>
+---
+
+--- a/Documentation/ABI/testing/sysfs-class-net
++++ b/Documentation/ABI/testing/sysfs-class-net
+@@ -301,3 +301,18 @@ Contact: netdev@vger.kernel.org
+ Description:
+ 32-bit unsigned integer counting the number of times the link has
+ been down
++
++What: /sys/class/net/<iface>/threaded
++Date: Jan 2021
++KernelVersion: 5.12
++Contact: netdev@vger.kernel.org
++Description:
++ Boolean value to control the threaded mode per device. User could
++ set this value to enable/disable threaded mode for all napi
++ belonging to this device, without the need to do device up/down.
++
++ Possible values:
++ == ==================================
++ 0 threaded mode disabled for this dev
++ 1 threaded mode enabled for this dev
++ == ==================================
+--- a/include/linux/netdevice.h
++++ b/include/linux/netdevice.h
+@@ -507,6 +507,8 @@ static inline bool napi_complete(struct
+ */
+ bool napi_hash_del(struct napi_struct *napi);
+
++int dev_set_threaded(struct net_device *dev, bool threaded);
++
+ /**
+ * napi_disable - prevent NAPI from scheduling
+ * @n: NAPI context
+--- a/net/core/dev.c
++++ b/net/core/dev.c
+@@ -3917,8 +3917,9 @@ static inline void ____napi_schedule(str
+
+ if (test_bit(NAPI_STATE_THREADED, &napi->state)) {
+ /* Paired with smp_mb__before_atomic() in
+- * napi_enable(). Use READ_ONCE() to guarantee
+- * a complete read on napi->thread. Only call
++ * napi_enable()/dev_set_threaded().
++ * Use READ_ONCE() to guarantee a complete
++ * read on napi->thread. Only call
+ * wake_up_process() when it's not NULL.
+ */
+ thread = READ_ONCE(napi->thread);
+@@ -6296,6 +6297,49 @@ static void init_gro_hash(struct napi_st
+ napi->gro_bitmask = 0;
+ }
+
++int dev_set_threaded(struct net_device *dev, bool threaded)
++{
++ struct napi_struct *napi;
++ int err = 0;
++
++ if (dev->threaded == threaded)
++ return 0;
++
++ if (threaded) {
++ list_for_each_entry(napi, &dev->napi_list, dev_list) {
++ if (!napi->thread) {
++ err = napi_kthread_create(napi);
++ if (err) {
++ threaded = false;
++ break;
++ }
++ }
++ }
++ }
++
++ dev->threaded = threaded;
++
++ /* Make sure kthread is created before THREADED bit
++ * is set.
++ */
++ smp_mb__before_atomic();
++
++ /* Setting/unsetting threaded mode on a napi might not immediately
++ * take effect, if the current napi instance is actively being
++ * polled. In this case, the switch between threaded mode and
++ * softirq mode will happen in the next round of napi_schedule().
++ * This should not cause hiccups/stalls to the live traffic.
++ */
++ list_for_each_entry(napi, &dev->napi_list, dev_list) {
++ if (threaded)
++ set_bit(NAPI_STATE_THREADED, &napi->state);
++ else
++ clear_bit(NAPI_STATE_THREADED, &napi->state);
++ }
++
++ return err;
++}
++
+ void netif_napi_add(struct net_device *dev, struct napi_struct *napi,
+ int (*poll)(struct napi_struct *, int), int weight)
+ {
+--- a/net/core/net-sysfs.c
++++ b/net/core/net-sysfs.c
+@@ -557,6 +557,45 @@ static ssize_t phys_switch_id_show(struc
+ }
+ static DEVICE_ATTR_RO(phys_switch_id);
+
++static ssize_t threaded_show(struct device *dev,
++ struct device_attribute *attr, char *buf)
++{
++ struct net_device *netdev = to_net_dev(dev);
++ ssize_t ret = -EINVAL;
++
++ if (!rtnl_trylock())
++ return restart_syscall();
++
++ if (dev_isalive(netdev))
++ ret = sprintf(buf, fmt_dec, netdev->threaded);
++
++ rtnl_unlock();
++ return ret;
++}
++
++static int modify_napi_threaded(struct net_device *dev, unsigned long val)
++{
++ int ret;
++
++ if (list_empty(&dev->napi_list))
++ return -EOPNOTSUPP;
++
++ if (val != 0 && val != 1)
++ return -EOPNOTSUPP;
++
++ ret = dev_set_threaded(dev, val);
++
++ return ret;
++}
++
++static ssize_t threaded_store(struct device *dev,
++ struct device_attribute *attr,
++ const char *buf, size_t len)
++{
++ return netdev_store(dev, attr, buf, len, modify_napi_threaded);
++}
++static DEVICE_ATTR_RW(threaded);
++
+ static struct attribute *net_class_attrs[] __ro_after_init = {
+ &dev_attr_netdev_group.attr,
+ &dev_attr_type.attr,
+@@ -587,6 +626,7 @@ static struct attribute *net_class_attrs
+ &dev_attr_proto_down.attr,
+ &dev_attr_carrier_up_count.attr,
+ &dev_attr_carrier_down_count.attr,
++ &dev_attr_threaded.attr,
+ NULL,
+ };
+ ATTRIBUTE_GROUPS(net_class);