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appletalk: stop storing per-interface state in struct net_device

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AppleTalk keeps its per-interface control block (struct atalk_iface)
directly in struct netdevice (dev->atalk_ptr). This is the only thing
tying the protocol into the core net_device layout and is the sole
blocker to moving AppleTalk out of tree.

Replace dev->atalk_ptr with a small ifindex-keyed hashtable internal
to ddp.c. The existing atalk_interfaces list stays the owner of the iface
objects; the hashtable is purely a fast dev->iface index and reuses
the same atalk_interfaces_lock.

AFAICT this patch does not make this code any more racy than it already
is, I'm sure Sashiko will point out some basically existing bugs.
AFAICT atalk_interfaces_lock is the innermost lock already.

Acked-by: Stephen Hemminger <stephen@networkplumber.org>
Link: https://patch.msgid.link/20260615222935.947233-2-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Jakub Kicinski
2026-06-15 15:29:34 -07:00
parent ffaf896773
commit 023f9b0f2f
4 changed files with 45 additions and 16 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
Documentation/networking/net_cachelines/net_device.rst
View File

@@ -90,7 +90,6 @@ struct inet6_dev* ip6_ptr read_mostly
struct vlan_info* vlan_info
struct dsa_port* dsa_ptr
struct tipc_bearer* tipc_ptr
void* atalk_ptr
struct wireless_dev* ieee80211_ptr
struct wpan_dev* ieee802154_ptr
struct mpls_dev* mpls_ptr

8
include/linux/atalk.h
View File

@@ -30,6 +30,7 @@ struct atalk_iface {
#define ATIF_PROBE_FAIL 2 /* Probe collided */
struct atalk_netrange nets;
struct atalk_iface *next;
struct hlist_node hash_node; /* keyed on dev->ifindex */
};
struct atalk_sock {
@@ -113,12 +114,7 @@ extern int aarp_proto_init(void);
/* Inter module exports */
/* Give a device find its atif control structure */
#if IS_ENABLED(CONFIG_ATALK)
static inline struct atalk_iface *atalk_find_dev(struct net_device *dev)
{
return dev->atalk_ptr;
}
#endif
extern struct atalk_iface *atalk_find_dev(struct net_device *dev);
extern struct atalk_addr *atalk_find_dev_addr(struct net_device *dev);
extern struct net_device *atrtr_get_dev(struct atalk_addr *sa);

4
include/linux/netdevice.h
View File

@@ -1947,7 +1947,6 @@ enum netdev_reg_state {
* @vlan_info: VLAN info
* @dsa_ptr: dsa specific data
* @tipc_ptr: TIPC specific data
* @atalk_ptr: AppleTalk link
* @ip_ptr: IPv4 specific data
* @ip6_ptr: IPv6 specific data
* @ieee80211_ptr: IEEE 802.11 specific data, assign before registering
@@ -2349,9 +2348,6 @@ struct net_device {
#if IS_ENABLED(CONFIG_TIPC)
struct tipc_bearer __rcu *tipc_ptr;
#endif
#if IS_ENABLED(CONFIG_ATALK)
void *atalk_ptr;
#endif
#if IS_ENABLED(CONFIG_CFG80211)
struct wireless_dev *ieee80211_ptr;
#endif

48
net/appletalk/ddp.c
View File

@@ -52,6 +52,7 @@
#include <linux/termios.h> /* For TIOCOUTQ/INQ */
#include <linux/compat.h>
#include <linux/slab.h>
#include <linux/hashtable.h>
#include <net/datalink.h>
#include <net/psnap.h>
#include <net/sock.h>
@@ -204,6 +205,33 @@ DEFINE_RWLOCK(atalk_routes_lock);
struct atalk_iface *atalk_interfaces;
DEFINE_RWLOCK(atalk_interfaces_lock);
/* Fast dev->iface lookup, keyed on ifindex. Shares atalk_interfaces_lock with
* the atalk_interfaces list, which remains the owner of the iface objects.
*/
#define ATALK_IFACE_HASH_BITS 8
static DEFINE_HASHTABLE(atalk_iface_hash, ATALK_IFACE_HASH_BITS);
/* Find the iface for @dev. Caller must hold atalk_interfaces_lock. */
static struct atalk_iface *__atalk_find_dev(struct net_device *dev)
{
struct atalk_iface *iface;
hash_for_each_possible(atalk_iface_hash, iface, hash_node, dev->ifindex)
if (iface->dev == dev)
return iface;
return NULL;
}
struct atalk_iface *atalk_find_dev(struct net_device *dev)
{
struct atalk_iface *iface;
read_lock_bh(&atalk_interfaces_lock);
iface = __atalk_find_dev(dev);
read_unlock_bh(&atalk_interfaces_lock);
return iface;
}
/* For probing devices or in a routerless network */
struct atalk_route atrtr_default;
@@ -221,9 +249,9 @@ static void atif_drop_device(struct net_device *dev)
while ((tmp = *iface) != NULL) {
if (tmp->dev == dev) {
*iface = tmp->next;
hash_del(&tmp->hash_node);
dev_put(dev);
kfree(tmp);
dev->atalk_ptr = NULL;
} else
iface = &tmp->next;
}
@@ -240,13 +268,13 @@ static struct atalk_iface *atif_add_device(struct net_device *dev,
dev_hold(dev);
iface->dev = dev;
dev->atalk_ptr = iface;
iface->address = *sa;
iface->status = 0;
write_lock_bh(&atalk_interfaces_lock);
iface->next = atalk_interfaces;
atalk_interfaces = iface;
hash_add(atalk_iface_hash, &iface->hash_node, dev->ifindex);
write_unlock_bh(&atalk_interfaces_lock);
out:
return iface;
@@ -347,8 +375,15 @@ static int atif_proxy_probe_device(struct atalk_iface *atif,
struct atalk_addr *atalk_find_dev_addr(struct net_device *dev)
{
struct atalk_iface *iface = dev->atalk_ptr;
return iface ? &iface->address : NULL;
struct atalk_addr *addr = NULL;
struct atalk_iface *iface;
read_lock_bh(&atalk_interfaces_lock);
iface = __atalk_find_dev(dev);
if (iface)
addr = &iface->address;
read_unlock_bh(&atalk_interfaces_lock);
return addr;
}
static struct atalk_addr *atalk_find_primary(void)
@@ -388,8 +423,10 @@ static struct atalk_addr *atalk_find_primary(void)
*/
static struct atalk_iface *atalk_find_anynet(int node, struct net_device *dev)
{
struct atalk_iface *iface = dev->atalk_ptr;
struct atalk_iface *iface;
read_lock_bh(&atalk_interfaces_lock);
iface = __atalk_find_dev(dev);
if (!iface || iface->status & ATIF_PROBE)
goto out_err;
@@ -398,6 +435,7 @@ static struct atalk_iface *atalk_find_anynet(int node, struct net_device *dev)
node != ATADDR_ANYNODE)
goto out_err;
out:
read_unlock_bh(&atalk_interfaces_lock);
return iface;
out_err:
iface = NULL;