6.8-stable review patch. If anyone has any objections, please let me know.
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From: Duoming Zhou duoming@zju.edu.cn
[ Upstream commit a7d6e36b9ad052926ba2ecba3a59d8bb67dabcb4 ]
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.171524701... Signed-off-by: Jakub Kicinski kuba@kernel.org Stable-dep-of: b505e0319852 ("ax25: Fix reference count leak issues of ax25_dev") Signed-off-by: Sasha Levin sashal@kernel.org --- include/net/ax25.h | 3 +-- net/ax25/ax25_dev.c | 40 +++++++++++++++------------------------- 2 files changed, 16 insertions(+), 27 deletions(-)
diff --git a/include/net/ax25.h b/include/net/ax25.h index 0d939e5aee4ec..c2a85fd3f5ea4 100644 --- a/include/net/ax25.h +++ b/include/net/ax25.h @@ -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) diff --git a/net/ax25/ax25_dev.c b/net/ax25/ax25_dev.c index 282ec581c0720..f16ee5c09d07a 100644 --- a/net/ax25/ax25_dev.c +++ b/net/ax25/ax25_dev.c @@ -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); }