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net: core: add ignore flag to netdev_adjacent structure
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In order to link an adjacent node, netdev_upper_dev_link() is used
and in order to unlink an adjacent node, netdev_upper_dev_unlink() is used.
unlink operation does not fail, but link operation can fail.

In order to exchange adjacent nodes, we should unlink an old adjacent
node first. then, link a new adjacent node.
If link operation is failed, we should link an old adjacent node again.
But this link operation can fail too.
It eventually breaks the adjacent link relationship.

This patch adds an ignore flag into the netdev_adjacent structure.
If this flag is set, netdev_upper_dev_link() ignores an old adjacent
node for a moment.

This patch also adds new functions for other modules.
netdev_adjacent_change_prepare()
netdev_adjacent_change_commit()
netdev_adjacent_change_abort()

netdev_adjacent_change_prepare() inserts new device into adjacent list
but new device is not allowed to use immediately.
If netdev_adjacent_change_prepare() fails, it internally rollbacks
adjacent list so that we don't need any other action.
netdev_adjacent_change_commit() deletes old device in the adjacent list
and allows new device to use.
netdev_adjacent_change_abort() rollbacks adjacent list.

Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Taehee Yoo authored and David S. Miller committed Oct 24, 2019
1 parent 2bce1eb commit 32b6d34
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Showing 2 changed files with 219 additions and 21 deletions.
10 changes: 10 additions & 0 deletions include/linux/netdevice.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -4324,6 +4324,16 @@ int netdev_master_upper_dev_link(struct net_device *dev,
struct netlink_ext_ack *extack);
void netdev_upper_dev_unlink(struct net_device *dev,
struct net_device *upper_dev);
int netdev_adjacent_change_prepare(struct net_device *old_dev,
struct net_device *new_dev,
struct net_device *dev,
struct netlink_ext_ack *extack);
void netdev_adjacent_change_commit(struct net_device *old_dev,
struct net_device *new_dev,
struct net_device *dev);
void netdev_adjacent_change_abort(struct net_device *old_dev,
struct net_device *new_dev,
struct net_device *dev);
void netdev_adjacent_rename_links(struct net_device *dev, char *oldname);
void *netdev_lower_dev_get_private(struct net_device *dev,
struct net_device *lower_dev);
Expand Down
230 changes: 209 additions & 21 deletions net/core/dev.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -6408,6 +6408,9 @@ struct netdev_adjacent {
/* upper master flag, there can only be one master device per list */
bool master;

/* lookup ignore flag */
bool ignore;

/* counter for the number of times this device was added to us */
u16 ref_nr;

Expand All @@ -6430,7 +6433,7 @@ static struct netdev_adjacent *__netdev_find_adj(struct net_device *adj_dev,
return NULL;
}

static int __netdev_has_upper_dev(struct net_device *upper_dev, void *data)
static int ____netdev_has_upper_dev(struct net_device *upper_dev, void *data)
{
struct net_device *dev = data;

Expand All @@ -6451,7 +6454,7 @@ bool netdev_has_upper_dev(struct net_device *dev,
{
ASSERT_RTNL();

return netdev_walk_all_upper_dev_rcu(dev, __netdev_has_upper_dev,
return netdev_walk_all_upper_dev_rcu(dev, ____netdev_has_upper_dev,
upper_dev);
}
EXPORT_SYMBOL(netdev_has_upper_dev);
Expand All @@ -6469,7 +6472,7 @@ EXPORT_SYMBOL(netdev_has_upper_dev);
bool netdev_has_upper_dev_all_rcu(struct net_device *dev,
struct net_device *upper_dev)
{
return !!netdev_walk_all_upper_dev_rcu(dev, __netdev_has_upper_dev,
return !!netdev_walk_all_upper_dev_rcu(dev, ____netdev_has_upper_dev,
upper_dev);
}
EXPORT_SYMBOL(netdev_has_upper_dev_all_rcu);
Expand Down Expand Up @@ -6513,6 +6516,22 @@ struct net_device *netdev_master_upper_dev_get(struct net_device *dev)
}
EXPORT_SYMBOL(netdev_master_upper_dev_get);

static struct net_device *__netdev_master_upper_dev_get(struct net_device *dev)
{
struct netdev_adjacent *upper;

ASSERT_RTNL();

if (list_empty(&dev->adj_list.upper))
return NULL;

upper = list_first_entry(&dev->adj_list.upper,
struct netdev_adjacent, list);
if (likely(upper->master) && !upper->ignore)
return upper->dev;
return NULL;
}

/**
* netdev_has_any_lower_dev - Check if device is linked to some device
* @dev: device
Expand Down Expand Up @@ -6563,8 +6582,9 @@ struct net_device *netdev_upper_get_next_dev_rcu(struct net_device *dev,
}
EXPORT_SYMBOL(netdev_upper_get_next_dev_rcu);

static struct net_device *netdev_next_upper_dev(struct net_device *dev,
struct list_head **iter)
static struct net_device *__netdev_next_upper_dev(struct net_device *dev,
struct list_head **iter,
bool *ignore)
{
struct netdev_adjacent *upper;

Expand All @@ -6574,6 +6594,7 @@ static struct net_device *netdev_next_upper_dev(struct net_device *dev,
return NULL;

*iter = &upper->list;
*ignore = upper->ignore;

return upper->dev;
}
Expand All @@ -6595,14 +6616,15 @@ static struct net_device *netdev_next_upper_dev_rcu(struct net_device *dev,
return upper->dev;
}

static int netdev_walk_all_upper_dev(struct net_device *dev,
int (*fn)(struct net_device *dev,
void *data),
void *data)
static int __netdev_walk_all_upper_dev(struct net_device *dev,
int (*fn)(struct net_device *dev,
void *data),
void *data)
{
struct net_device *udev, *next, *now, *dev_stack[MAX_NEST_DEV + 1];
struct list_head *niter, *iter, *iter_stack[MAX_NEST_DEV + 1];
int ret, cur = 0;
bool ignore;

now = dev;
iter = &dev->adj_list.upper;
Expand All @@ -6616,9 +6638,11 @@ static int netdev_walk_all_upper_dev(struct net_device *dev,

next = NULL;
while (1) {
udev = netdev_next_upper_dev(now, &iter);
udev = __netdev_next_upper_dev(now, &iter, &ignore);
if (!udev)
break;
if (ignore)
continue;

next = udev;
niter = &udev->adj_list.upper;
Expand Down Expand Up @@ -6688,6 +6712,15 @@ int netdev_walk_all_upper_dev_rcu(struct net_device *dev,
}
EXPORT_SYMBOL_GPL(netdev_walk_all_upper_dev_rcu);

static bool __netdev_has_upper_dev(struct net_device *dev,
struct net_device *upper_dev)
{
ASSERT_RTNL();

return __netdev_walk_all_upper_dev(dev, ____netdev_has_upper_dev,
upper_dev);
}

/**
* netdev_lower_get_next_private - Get the next ->private from the
* lower neighbour list
Expand Down Expand Up @@ -6784,6 +6817,23 @@ static struct net_device *netdev_next_lower_dev(struct net_device *dev,
return lower->dev;
}

static struct net_device *__netdev_next_lower_dev(struct net_device *dev,
struct list_head **iter,
bool *ignore)
{
struct netdev_adjacent *lower;

lower = list_entry((*iter)->next, struct netdev_adjacent, list);

if (&lower->list == &dev->adj_list.lower)
return NULL;

*iter = &lower->list;
*ignore = lower->ignore;

return lower->dev;
}

int netdev_walk_all_lower_dev(struct net_device *dev,
int (*fn)(struct net_device *dev,
void *data),
Expand Down Expand Up @@ -6831,6 +6881,55 @@ int netdev_walk_all_lower_dev(struct net_device *dev,
}
EXPORT_SYMBOL_GPL(netdev_walk_all_lower_dev);

static int __netdev_walk_all_lower_dev(struct net_device *dev,
int (*fn)(struct net_device *dev,
void *data),
void *data)
{
struct net_device *ldev, *next, *now, *dev_stack[MAX_NEST_DEV + 1];
struct list_head *niter, *iter, *iter_stack[MAX_NEST_DEV + 1];
int ret, cur = 0;
bool ignore;

now = dev;
iter = &dev->adj_list.lower;

while (1) {
if (now != dev) {
ret = fn(now, data);
if (ret)
return ret;
}

next = NULL;
while (1) {
ldev = __netdev_next_lower_dev(now, &iter, &ignore);
if (!ldev)
break;
if (ignore)
continue;

next = ldev;
niter = &ldev->adj_list.lower;
dev_stack[cur] = now;
iter_stack[cur++] = iter;
break;
}

if (!next) {
if (!cur)
return 0;
next = dev_stack[--cur];
niter = iter_stack[cur];
}

now = next;
iter = niter;
}

return 0;
}

static struct net_device *netdev_next_lower_dev_rcu(struct net_device *dev,
struct list_head **iter)
{
Expand All @@ -6850,11 +6949,14 @@ static u8 __netdev_upper_depth(struct net_device *dev)
struct net_device *udev;
struct list_head *iter;
u8 max_depth = 0;
bool ignore;

for (iter = &dev->adj_list.upper,
udev = netdev_next_upper_dev(dev, &iter);
udev = __netdev_next_upper_dev(dev, &iter, &ignore);
udev;
udev = netdev_next_upper_dev(dev, &iter)) {
udev = __netdev_next_upper_dev(dev, &iter, &ignore)) {
if (ignore)
continue;
if (max_depth < udev->upper_level)
max_depth = udev->upper_level;
}
Expand All @@ -6867,11 +6969,14 @@ static u8 __netdev_lower_depth(struct net_device *dev)
struct net_device *ldev;
struct list_head *iter;
u8 max_depth = 0;
bool ignore;

for (iter = &dev->adj_list.lower,
ldev = netdev_next_lower_dev(dev, &iter);
ldev = __netdev_next_lower_dev(dev, &iter, &ignore);
ldev;
ldev = netdev_next_lower_dev(dev, &iter)) {
ldev = __netdev_next_lower_dev(dev, &iter, &ignore)) {
if (ignore)
continue;
if (max_depth < ldev->lower_level)
max_depth = ldev->lower_level;
}
Expand Down Expand Up @@ -7035,6 +7140,7 @@ static int __netdev_adjacent_dev_insert(struct net_device *dev,
adj->master = master;
adj->ref_nr = 1;
adj->private = private;
adj->ignore = false;
dev_hold(adj_dev);

pr_debug("Insert adjacency: dev %s adj_dev %s adj->ref_nr %d; dev_hold on %s\n",
Expand Down Expand Up @@ -7185,17 +7291,17 @@ static int __netdev_upper_dev_link(struct net_device *dev,
return -EBUSY;

/* To prevent loops, check if dev is not upper device to upper_dev. */
if (netdev_has_upper_dev(upper_dev, dev))
if (__netdev_has_upper_dev(upper_dev, dev))
return -EBUSY;

if ((dev->lower_level + upper_dev->upper_level) > MAX_NEST_DEV)
return -EMLINK;

if (!master) {
if (netdev_has_upper_dev(dev, upper_dev))
if (__netdev_has_upper_dev(dev, upper_dev))
return -EEXIST;
} else {
master_dev = netdev_master_upper_dev_get(dev);
master_dev = __netdev_master_upper_dev_get(dev);
if (master_dev)
return master_dev == upper_dev ? -EEXIST : -EBUSY;
}
Expand All @@ -7218,10 +7324,11 @@ static int __netdev_upper_dev_link(struct net_device *dev,
goto rollback;

__netdev_update_upper_level(dev, NULL);
netdev_walk_all_lower_dev(dev, __netdev_update_upper_level, NULL);
__netdev_walk_all_lower_dev(dev, __netdev_update_upper_level, NULL);

__netdev_update_lower_level(upper_dev, NULL);
netdev_walk_all_upper_dev(upper_dev, __netdev_update_lower_level, NULL);
__netdev_walk_all_upper_dev(upper_dev, __netdev_update_lower_level,
NULL);

return 0;

Expand Down Expand Up @@ -7307,13 +7414,94 @@ void netdev_upper_dev_unlink(struct net_device *dev,
&changeupper_info.info);

__netdev_update_upper_level(dev, NULL);
netdev_walk_all_lower_dev(dev, __netdev_update_upper_level, NULL);
__netdev_walk_all_lower_dev(dev, __netdev_update_upper_level, NULL);

__netdev_update_lower_level(upper_dev, NULL);
netdev_walk_all_upper_dev(upper_dev, __netdev_update_lower_level, NULL);
__netdev_walk_all_upper_dev(upper_dev, __netdev_update_lower_level,
NULL);
}
EXPORT_SYMBOL(netdev_upper_dev_unlink);

static void __netdev_adjacent_dev_set(struct net_device *upper_dev,
struct net_device *lower_dev,
bool val)
{
struct netdev_adjacent *adj;

adj = __netdev_find_adj(lower_dev, &upper_dev->adj_list.lower);
if (adj)
adj->ignore = val;

adj = __netdev_find_adj(upper_dev, &lower_dev->adj_list.upper);
if (adj)
adj->ignore = val;
}

static void netdev_adjacent_dev_disable(struct net_device *upper_dev,
struct net_device *lower_dev)
{
__netdev_adjacent_dev_set(upper_dev, lower_dev, true);
}

static void netdev_adjacent_dev_enable(struct net_device *upper_dev,
struct net_device *lower_dev)
{
__netdev_adjacent_dev_set(upper_dev, lower_dev, false);
}

int netdev_adjacent_change_prepare(struct net_device *old_dev,
struct net_device *new_dev,
struct net_device *dev,
struct netlink_ext_ack *extack)
{
int err;

if (!new_dev)
return 0;

if (old_dev && new_dev != old_dev)
netdev_adjacent_dev_disable(dev, old_dev);

err = netdev_upper_dev_link(new_dev, dev, extack);
if (err) {
if (old_dev && new_dev != old_dev)
netdev_adjacent_dev_enable(dev, old_dev);
return err;
}

return 0;
}
EXPORT_SYMBOL(netdev_adjacent_change_prepare);

void netdev_adjacent_change_commit(struct net_device *old_dev,
struct net_device *new_dev,
struct net_device *dev)
{
if (!new_dev || !old_dev)
return;

if (new_dev == old_dev)
return;

netdev_adjacent_dev_enable(dev, old_dev);
netdev_upper_dev_unlink(old_dev, dev);
}
EXPORT_SYMBOL(netdev_adjacent_change_commit);

void netdev_adjacent_change_abort(struct net_device *old_dev,
struct net_device *new_dev,
struct net_device *dev)
{
if (!new_dev)
return;

if (old_dev && new_dev != old_dev)
netdev_adjacent_dev_enable(dev, old_dev);

netdev_upper_dev_unlink(new_dev, dev);
}
EXPORT_SYMBOL(netdev_adjacent_change_abort);

/**
* netdev_bonding_info_change - Dispatch event about slave change
* @dev: device
Expand Down

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