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ax25: Use kernel universal linked list to implement ax25_dev_list

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The origin ax25_dev_list implements its own single linked list,
which is complicated and error-prone. For example, when deleting
the node of ax25_dev_list in ax25_dev_device_down(), we have to
operate on the head node and other nodes separately.

This patch uses kernel universal linked list to replace original
ax25_dev_list, which make the operation of ax25_dev_list easier.

We should do "dev->ax25_ptr = ax25_dev;" and "dev->ax25_ptr = NULL;"
while holding the spinlock, otherwise the ax25_dev_device_up() and
ax25_dev_device_down() could race.

Suggested-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
Reviewed-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://lore.kernel.org/r/85bba3af651ca0e1a519da8d0d715b949891171c.1715247018.git.duoming@zju.edu.cn
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Duoming Zhou 2024-05-09 17:36:33 +08:00 committed by Jakub Kicinski
parent ecf848eb93
commit a7d6e36b9a
2 changed files with 16 additions and 27 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
include/net/ax25.h
View File

@ -216,7 +216,7 @@ typedef struct {
struct ctl_table;
typedef struct ax25_dev {
struct ax25_dev *next;
struct list_head list;
struct net_device *dev;
netdevice_tracker dev_tracker;
@ -330,7 +330,6 @@ int ax25_addr_size(const ax25_digi *);
void ax25_digi_invert(const ax25_digi *, ax25_digi *);
/* ax25_dev.c */
extern ax25_dev *ax25_dev_list;
extern spinlock_t ax25_dev_lock;
#if IS_ENABLED(CONFIG_AX25)

40
net/ax25/ax25_dev.c
View File

@ -22,11 +22,12 @@
#include <net/sock.h>
#include <linux/uaccess.h>
#include <linux/fcntl.h>
#include <linux/list.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/init.h>
ax25_dev *ax25_dev_list;
static LIST_HEAD(ax25_dev_list);
DEFINE_SPINLOCK(ax25_dev_lock);
ax25_dev *ax25_addr_ax25dev(ax25_address *addr)
@ -34,7 +35,7 @@ ax25_dev *ax25_addr_ax25dev(ax25_address *addr)
ax25_dev *ax25_dev, *res = NULL;
spin_lock_bh(&ax25_dev_lock);
for (ax25_dev = ax25_dev_list; ax25_dev != NULL; ax25_dev = ax25_dev->next)
list_for_each_entry(ax25_dev, &ax25_dev_list, list)
if (ax25cmp(addr, (const ax25_address *)ax25_dev->dev->dev_addr) == 0) {
res = ax25_dev;
ax25_dev_hold(ax25_dev);
@ -59,7 +60,6 @@ void ax25_dev_device_up(struct net_device *dev)
}
refcount_set(&ax25_dev->refcount, 1);
dev->ax25_ptr = ax25_dev;
ax25_dev->dev = dev;
netdev_hold(dev, &ax25_dev->dev_tracker, GFP_KERNEL);
ax25_dev->forward = NULL;
@ -85,8 +85,8 @@ void ax25_dev_device_up(struct net_device *dev)
#endif
spin_lock_bh(&ax25_dev_lock);
ax25_dev->next = ax25_dev_list;
ax25_dev_list = ax25_dev;
list_add(&ax25_dev->list, &ax25_dev_list);
dev->ax25_ptr = ax25_dev;
spin_unlock_bh(&ax25_dev_lock);
ax25_dev_hold(ax25_dev);
@ -111,32 +111,25 @@ void ax25_dev_device_down(struct net_device *dev)
/*
* Remove any packet forwarding that points to this device.
*/
for (s = ax25_dev_list; s != NULL; s = s->next)
list_for_each_entry(s, &ax25_dev_list, list)
if (s->forward == dev)
s->forward = NULL;
if ((s = ax25_dev_list) == ax25_dev) {
ax25_dev_list = s->next;
goto unlock_put;
}
while (s != NULL && s->next != NULL) {
if (s->next == ax25_dev) {
s->next = ax25_dev->next;
list_for_each_entry(s, &ax25_dev_list, list) {
if (s == ax25_dev) {
list_del(&s->list);
goto unlock_put;
}
s = s->next;
}
spin_unlock_bh(&ax25_dev_lock);
dev->ax25_ptr = NULL;
spin_unlock_bh(&ax25_dev_lock);
ax25_dev_put(ax25_dev);
return;
unlock_put:
dev->ax25_ptr = NULL;
spin_unlock_bh(&ax25_dev_lock);
ax25_dev_put(ax25_dev);
dev->ax25_ptr = NULL;
netdev_put(dev, &ax25_dev->dev_tracker);
ax25_dev_put(ax25_dev);
}
@ -200,16 +193,13 @@ struct net_device *ax25_fwd_dev(struct net_device *dev)
*/
void __exit ax25_dev_free(void)
{
ax25_dev *s, *ax25_dev;
ax25_dev *s, *n;
spin_lock_bh(&ax25_dev_lock);
ax25_dev = ax25_dev_list;
while (ax25_dev != NULL) {
s = ax25_dev;
netdev_put(ax25_dev->dev, &ax25_dev->dev_tracker);
ax25_dev = ax25_dev->next;
list_for_each_entry_safe(s, n, &ax25_dev_list, list) {
netdev_put(s->dev, &s->dev_tracker);
list_del(&s->list);
kfree(s);
}
ax25_dev_list = NULL;
spin_unlock_bh(&ax25_dev_lock);
}