diff options
Diffstat (limited to 'target/linux/generic/backport-5.4/602-v5.12-net-add-sysfs-attribute-to-control-napi-threaded-mod.patch')
| -rw-r--r-- | target/linux/generic/backport-5.4/602-v5.12-net-add-sysfs-attribute-to-control-napi-threaded-mod.patch | 177 |
1 files changed, 177 insertions, 0 deletions
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 0000000000..d8b932978c --- /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 +@@ -498,6 +498,8 @@ 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 +@@ -3911,8 +3911,9 @@ 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); +@@ -6290,6 +6291,49 @@ 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); |