[PATCH net-next 1/5] netdevice: convert private flags > BIT(31) to bitfields

Alexander Lobakin
2024-06-25T11:49:59Z

Make dev->priv_flags `u32` back and define bits higher than 31 as
bitfield booleans as per Jakub's suggestion. This simplifies code
which accesses these bits with no optimization loss (testb both
before/after), allows to not extend &netdev_priv_flags each time,
but also scales better as bits > 63 in the future would only add
a new u64 to the structure with no complications, comparing to
that extending ::priv_flags would require converting it to a bitmap.
Note that I picked `unsigned long :1` to not lose any potential
optimizations comparing to `bool :1` etc.

Suggested-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
---
include/linux/netdevice.h | 27 ++++++++++++-------
.../ethernet/microchip/lan966x/lan966x_main.c | 2 +-
drivers/net/macvlan.c | 3 ++-
drivers/net/vxlan/vxlan_core.c | 3 ++-
net/8021q/vlanproc.c | 2 +-
net/core/dev.c | 4 +--
net/core/dev_ioctl.c | 9 +++----
net/core/rtnetlink.c | 2 +-
8 files changed, 30 insertions(+), 22 deletions(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 4e81660b4462..4fddf57f40d9 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1607,7 +1607,8 @@ struct net_device_ops {
* userspace; this means that the order of these flags can change
* during any kernel release.
*
- * You should have a pretty good reason to be extending these flags.
+ * You should add bitfield booleans after net_device::priv_flags instead
+ * of extending these flags.
*
* @IFF_802_1Q_VLAN: 802.1Q VLAN device
* @IFF_EBRIDGE: Ethernet bridging device
@@ -1646,10 +1647,6 @@ struct net_device_ops {
* @IFF_NO_ADDRCONF: prevent ipv6 addrconf
* @IFF_TX_SKB_NO_LINEAR: device/driver is capable of xmitting frames with
* skb_headlen(skb) == 0 (data starts from frag0)
- * @IFF_CHANGE_PROTO_DOWN: device supports setting carrier via IFLA_PROTO_DOWN
- * @IFF_SEE_ALL_HWTSTAMP_REQUESTS: device wants to see calls to
- * ndo_hwtstamp_set() for all timestamp requests regardless of source,
- * even if those aren't HWTSTAMP_SOURCE_NETDEV.
*/
enum netdev_priv_flags {
IFF_802_1Q_VLAN = 1<<0,
@@ -1684,8 +1681,6 @@ enum netdev_priv_flags {
IFF_L3MDEV_RX_HANDLER = 1<<29,
IFF_NO_ADDRCONF = BIT_ULL(30),
IFF_TX_SKB_NO_LINEAR = BIT_ULL(31),
- IFF_CHANGE_PROTO_DOWN = BIT_ULL(32),
- IFF_SEE_ALL_HWTSTAMP_REQUESTS = BIT_ULL(33),
};

#define IFF_802_1Q_VLAN IFF_802_1Q_VLAN
@@ -1749,6 +1744,16 @@ enum netdev_reg_state {
* data with strictly "high-level" data, and it has to know about
* almost every data structure used in the INET module.
*
+ * @__priv_flags: both private flags as bits and as bitfield booleans
+ * combined, only to assert cacheline placement
+ * @priv_flags: flags invisible to userspace defined as bits, see
+ * enum netdev_priv_flags for the definitions
+ * @see_all_hwtstamp_requests: device wants to see calls to
+ * ndo_hwtstamp_set() for all timestamp requests
+ * regardless of source, even if those aren't
+ * HWTSTAMP_SOURCE_NETDEV
+ * @change_proto_down: device supports setting carrier via IFLA_PROTO_DOWN
+ *
* @name: This is the first field of the "visible" part of this structure
* (i.e. as seen by users in the "Space.c" file). It is the name
* of the interface.
@@ -1815,8 +1820,6 @@ enum netdev_reg_state {
*
* @flags: Interface flags (a la BSD)
* @xdp_features: XDP capability supported by the device
- * @priv_flags: Like 'flags' but invisible to userspace,
- * see if.h for the definitions
* @gflags: Global flags ( kept as legacy )
* @padded: How much padding added by alloc_netdev()
* @operstate: RFC2863 operstate
@@ -2039,7 +2042,11 @@ struct net_device {

/* TX read-mostly hotpath */
__cacheline_group_begin(net_device_read_tx);
- unsigned long long priv_flags;
+ struct_group(__priv_flags,
+ unsigned long priv_flags:32;
+ unsigned long see_all_hwtstamp_requests:1;
+ unsigned long change_proto_down:1;
+ );
const struct net_device_ops *netdev_ops;
const struct header_ops *header_ops;
struct netdev_queue *_tx;
diff --git a/drivers/net/ethernet/microchip/lan966x/lan966x_main.c b/drivers/net/ethernet/microchip/lan966x/lan966x_main.c
index ec672af12e25..534d4716d5f7 100644
--- a/drivers/net/ethernet/microchip/lan966x/lan966x_main.c
+++ b/drivers/net/ethernet/microchip/lan966x/lan966x_main.c
@@ -816,7 +816,7 @@ static int lan966x_probe_port(struct lan966x *lan966x, u32 p,
NETIF_F_HW_VLAN_STAG_TX |
NETIF_F_HW_TC;
dev->hw_features |= NETIF_F_HW_TC;
- dev->priv_flags |= IFF_SEE_ALL_HWTSTAMP_REQUESTS;
+ dev->see_all_hwtstamp_requests = true;
dev->needed_headroom = IFH_LEN_BYTES;

eth_hw_addr_gen(dev, lan966x->base_mac, p + 1);
diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
index 67b7ef2d463f..3aa6d33efdf5 100644
--- a/drivers/net/macvlan.c
+++ b/drivers/net/macvlan.c
@@ -1213,7 +1213,8 @@ void macvlan_common_setup(struct net_device *dev)
dev->max_mtu = ETH_MAX_MTU;
dev->priv_flags &= ~IFF_TX_SKB_SHARING;
netif_keep_dst(dev);
- dev->priv_flags |= IFF_UNICAST_FLT | IFF_CHANGE_PROTO_DOWN;
+ dev->priv_flags |= IFF_UNICAST_FLT;
+ dev->change_proto_down = true;
dev->netdev_ops = &macvlan_netdev_ops;
dev->needs_free_netdev = true;
dev->priv_destructor = macvlan_dev_free;
diff --git a/drivers/net/vxlan/vxlan_core.c b/drivers/net/vxlan/vxlan_core.c
index 567cb3faab70..2f3a7c58d302 100644
--- a/drivers/net/vxlan/vxlan_core.c
+++ b/drivers/net/vxlan/vxlan_core.c
@@ -3325,7 +3325,8 @@ static void vxlan_setup(struct net_device *dev)
dev->hw_features |= NETIF_F_RXCSUM;
dev->hw_features |= NETIF_F_GSO_SOFTWARE;
netif_keep_dst(dev);
- dev->priv_flags |= IFF_NO_QUEUE | IFF_CHANGE_PROTO_DOWN;
+ dev->priv_flags |= IFF_NO_QUEUE;
+ dev->change_proto_down = true;

/* MTU range: 68 - 65535 */
dev->min_mtu = ETH_MIN_MTU;
diff --git a/net/8021q/vlanproc.c b/net/8021q/vlanproc.c
index 87b959da00cd..e8ddf97dad63 100644
--- a/net/8021q/vlanproc.c
+++ b/net/8021q/vlanproc.c
@@ -238,7 +238,7 @@ static int vlandev_seq_show(struct seq_file *seq, void *offset)

stats = dev_get_stats(vlandev, &temp);
seq_printf(seq,
- "%s VID: %d REORDER_HDR: %i dev->priv_flags: %llx\n",
+ "%s VID: %d REORDER_HDR: %i dev->priv_flags: %x\n",
vlandev->name, vlan->vlan_id,
(int)(vlan->flags & 1), vlandev->priv_flags);

diff --git a/net/core/dev.c b/net/core/dev.c
index b94fb4e63a28..49a88b0ff73b 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -9266,7 +9266,7 @@ EXPORT_SYMBOL(netdev_port_same_parent_id);
*/
int dev_change_proto_down(struct net_device *dev, bool proto_down)
{
- if (!(dev->priv_flags & IFF_CHANGE_PROTO_DOWN))
+ if (!dev->change_proto_down)
return -EOPNOTSUPP;
if (!netif_device_present(dev))
return -ENODEV;
@@ -11869,7 +11869,7 @@ static struct pernet_operations __net_initdata default_device_ops = {
static void __init net_dev_struct_check(void)
{
/* TX read-mostly hotpath */
- CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_tx, priv_flags);
+ CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_tx, __priv_flags);
CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_tx, netdev_ops);
CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_tx, header_ops);
CACHELINE_ASSERT_GROUP_MEMBER(struct net_device, net_device_read_tx, _tx);
diff --git a/net/core/dev_ioctl.c b/net/core/dev_ioctl.c
index b9719ed3c3fd..3868486fb71f 100644
--- a/net/core/dev_ioctl.c
+++ b/net/core/dev_ioctl.c
@@ -319,8 +319,7 @@ static int dev_get_hwtstamp(struct net_device *dev, struct ifreq *ifr)
* should take precedence in front of hardware timestamping provided by the
* netdev. If the netdev driver needs to perform specific actions even for PHY
* timestamping to work properly (a switch port must trap the timestamped
- * frames and not forward them), it must set IFF_SEE_ALL_HWTSTAMP_REQUESTS in
- * dev->priv_flags.
+ * frames and not forward them), it must set dev->see_all_hwtstamp_requests.
*/
int dev_set_hwtstamp_phylib(struct net_device *dev,
struct kernel_hwtstamp_config *cfg,
@@ -334,13 +333,13 @@ int dev_set_hwtstamp_phylib(struct net_device *dev,

cfg->source = phy_ts ? HWTSTAMP_SOURCE_PHYLIB : HWTSTAMP_SOURCE_NETDEV;

- if (phy_ts && (dev->priv_flags & IFF_SEE_ALL_HWTSTAMP_REQUESTS)) {
+ if (phy_ts && dev->see_all_hwtstamp_requests) {
err = ops->ndo_hwtstamp_get(dev, &old_cfg);
if (err)
return err;
}

- if (!phy_ts || (dev->priv_flags & IFF_SEE_ALL_HWTSTAMP_REQUESTS)) {
+ if (!phy_ts || dev->see_all_hwtstamp_requests) {
err = ops->ndo_hwtstamp_set(dev, cfg, extack);
if (err) {
if (extack->_msg)
@@ -349,7 +348,7 @@ int dev_set_hwtstamp_phylib(struct net_device *dev,
}
}

- if (phy_ts && (dev->priv_flags & IFF_SEE_ALL_HWTSTAMP_REQUESTS))
+ if (phy_ts && dev->see_all_hwtstamp_requests)
changed = kernel_hwtstamp_config_changed(&old_cfg, cfg);

if (phy_ts) {
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index eabfc8290f5e..cff172f0ff3d 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -2724,7 +2724,7 @@ static int do_set_proto_down(struct net_device *dev,
bool proto_down;
int err;

- if (!(dev->priv_flags & IFF_CHANGE_PROTO_DOWN)) {
+ if (!dev->change_proto_down) {
NL_SET_ERR_MSG(extack, "Protodown not supported by device");
return -EOPNOTSUPP;
}
--
2.45.2