diff mbox series

[net-next,2/5] net: add sysfs attribute to control napi threaded mode

Message ID 20200930192140.4192859-3-weiwan@google.com
State Superseded
Headers show
Series implement kthread based napi poll | expand

Commit Message

Wei Wang Sept. 30, 2020, 7:21 p.m. UTC 
From: Paolo Abeni <pabeni@redhat.com> 

this patch adds a new sysfs attribute to the network
device class. Said attribute is a bitmask that allows controlling
the threaded mode for all the napi instances of the given
network device.

The threaded mode can be switched only if related network device
is down.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: Wei Wang <weiwan@google.com>
---
 net/core/net-sysfs.c | 103 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 103 insertions(+)
diff mbox series

Patch

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index efec66fa78b7..fe81b344447d 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -538,6 +538,108 @@  static ssize_t phys_switch_id_show(struct device *dev,
 }
 static DEVICE_ATTR_RO(phys_switch_id);
 
+static unsigned long *__alloc_thread_bitmap(struct net_device *netdev,
+					    int *bits)
+{
+	struct napi_struct *n;
+
+	*bits = 0;
+	list_for_each_entry(n, &netdev->napi_list, dev_list)
+		(*bits)++;
+
+	return kmalloc_array(BITS_TO_LONGS(*bits), sizeof(unsigned long),
+			     GFP_ATOMIC | __GFP_ZERO);
+}
+
+static ssize_t threaded_show(struct device *dev,
+			     struct device_attribute *attr, char *buf)
+{
+	struct net_device *netdev = to_net_dev(dev);
+	struct napi_struct *n;
+	unsigned long *bmap;
+	size_t count = 0;
+	int i, bits;
+
+	if (!rtnl_trylock())
+		return restart_syscall();
+
+	if (!dev_isalive(netdev))
+		goto unlock;
+
+	bmap = __alloc_thread_bitmap(netdev, &bits);
+	if (!bmap) {
+		count = -ENOMEM;
+		goto unlock;
+	}
+
+	i = 0;
+	list_for_each_entry(n, &netdev->napi_list, dev_list) {
+		if (test_bit(NAPI_STATE_THREADED, &n->state))
+			set_bit(i, bmap);
+		i++;
+	}
+
+	count = bitmap_print_to_pagebuf(true, buf, bmap, bits);
+	kfree(bmap);
+
+unlock:
+	rtnl_unlock();
+
+	return count;
+}
+
+static ssize_t threaded_store(struct device *dev,
+			      struct device_attribute *attr,
+			      const char *buf, size_t len)
+{
+	struct net_device *netdev = to_net_dev(dev);
+	struct napi_struct *n;
+	unsigned long *bmap;
+	int i, bits;
+	size_t ret;
+
+	if (!capable(CAP_NET_ADMIN))
+		return -EPERM;
+
+	if (!rtnl_trylock())
+		return restart_syscall();
+
+	if (!dev_isalive(netdev)) {
+		ret = len;
+		goto unlock;
+	}
+
+	if (netdev->flags & IFF_UP) {
+		ret = -EBUSY;
+		goto unlock;
+	}
+
+	bmap = __alloc_thread_bitmap(netdev, &bits);
+	if (!bmap) {
+		ret = -ENOMEM;
+		goto unlock;
+	}
+
+	ret = bitmap_parselist(buf, bmap, bits);
+	if (ret)
+		goto free_unlock;
+
+	i = 0;
+	list_for_each_entry(n, &netdev->napi_list, dev_list) {
+		napi_set_threaded(n, test_bit(i, bmap));
+		i++;
+	}
+	ret = len;
+
+free_unlock:
+	kfree(bmap);
+
+unlock:
+	rtnl_unlock();
+	return ret;
+}
+static DEVICE_ATTR_RW(threaded);
+
 static struct attribute *net_class_attrs[] __ro_after_init = {
 	&dev_attr_netdev_group.attr,
 	&dev_attr_type.attr,
@@ -570,6 +672,7 @@  static struct attribute *net_class_attrs[] __ro_after_init = {
 	&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);