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net: Introduce new api for walking upper and lower devices
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This patch introduces netdev_walk_all_upper_dev_rcu,
netdev_walk_all_lower_dev and netdev_walk_all_lower_dev_rcu. These
functions recursively walk the adj_list of devices to determine all upper
and lower devices.

The functions take a callback function that is invoked for each device
in the list. If the callback returns non-0, the walk is terminated and
the functions return that code back to callers.

v3
- simplified netdev_has_upper_dev_all_rcu and __netdev_has_upper_dev and
  removed typecast as suggested by Stephen

v2
- fixed definition of netdev_next_lower_dev_rcu to mirror the upper_dev
  version.

Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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David Ahern authored and David S. Miller committed Oct 18, 2016
1 parent 790510d commit 1a3f060
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17 changes: 17 additions & 0 deletions include/linux/netdevice.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -3778,6 +3778,14 @@ struct net_device *netdev_all_upper_get_next_dev_rcu(struct net_device *dev,
updev; \
updev = netdev_all_upper_get_next_dev_rcu(dev, &(iter)))

int netdev_walk_all_upper_dev_rcu(struct net_device *dev,
int (*fn)(struct net_device *upper_dev,
void *data),
void *data);

bool netdev_has_upper_dev_all_rcu(struct net_device *dev,
struct net_device *upper_dev);

void *netdev_lower_get_next_private(struct net_device *dev,
struct list_head **iter);
void *netdev_lower_get_next_private_rcu(struct net_device *dev,
Expand Down Expand Up @@ -3821,6 +3829,15 @@ struct net_device *netdev_all_lower_get_next_rcu(struct net_device *dev,
ldev; \
ldev = netdev_all_lower_get_next_rcu(dev, &(iter)))

int netdev_walk_all_lower_dev(struct net_device *dev,
int (*fn)(struct net_device *lower_dev,
void *data),
void *data);
int netdev_walk_all_lower_dev_rcu(struct net_device *dev,
int (*fn)(struct net_device *lower_dev,
void *data),
void *data);

void *netdev_adjacent_get_private(struct list_head *adj_list);
void *netdev_lower_get_first_private_rcu(struct net_device *dev);
struct net_device *netdev_master_upper_dev_get(struct net_device *dev);
Expand Down
155 changes: 155 additions & 0 deletions net/core/dev.c
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Original file line number Diff line number Diff line change
Expand Up @@ -5155,6 +5155,31 @@ bool netdev_has_upper_dev(struct net_device *dev,
}
EXPORT_SYMBOL(netdev_has_upper_dev);

/**
* netdev_has_upper_dev_all - Check if device is linked to an upper device
* @dev: device
* @upper_dev: upper device to check
*
* Find out if a device is linked to specified upper device and return true
* in case it is. Note that this checks the entire upper device chain.
* The caller must hold rcu lock.
*/

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

return upper_dev == 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,
upper_dev);
}
EXPORT_SYMBOL(netdev_has_upper_dev_all_rcu);

/**
* netdev_has_any_upper_dev - Check if device is linked to some device
* @dev: device
Expand Down Expand Up @@ -5255,6 +5280,51 @@ struct net_device *netdev_all_upper_get_next_dev_rcu(struct net_device *dev,
}
EXPORT_SYMBOL(netdev_all_upper_get_next_dev_rcu);

static struct net_device *netdev_next_upper_dev_rcu(struct net_device *dev,
struct list_head **iter)
{
struct netdev_adjacent *upper;

WARN_ON_ONCE(!rcu_read_lock_held() && !lockdep_rtnl_is_held());

upper = list_entry_rcu((*iter)->next, struct netdev_adjacent, list);

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

*iter = &upper->list;

return upper->dev;
}

int netdev_walk_all_upper_dev_rcu(struct net_device *dev,
int (*fn)(struct net_device *dev,
void *data),
void *data)
{
struct net_device *udev;
struct list_head *iter;
int ret;

for (iter = &dev->adj_list.upper,
udev = netdev_next_upper_dev_rcu(dev, &iter);
udev;
udev = netdev_next_upper_dev_rcu(dev, &iter)) {
/* first is the upper device itself */
ret = fn(udev, data);
if (ret)
return ret;

/* then look at all of its upper devices */
ret = netdev_walk_all_upper_dev_rcu(udev, fn, data);
if (ret)
return ret;
}

return 0;
}
EXPORT_SYMBOL_GPL(netdev_walk_all_upper_dev_rcu);

/**
* netdev_lower_get_next_private - Get the next ->private from the
* lower neighbour list
Expand Down Expand Up @@ -5361,6 +5431,49 @@ struct net_device *netdev_all_lower_get_next(struct net_device *dev, struct list
}
EXPORT_SYMBOL(netdev_all_lower_get_next);

static struct net_device *netdev_next_lower_dev(struct net_device *dev,
struct list_head **iter)
{
struct netdev_adjacent *lower;

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

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

*iter = lower->list.next;

return lower->dev;
}

int netdev_walk_all_lower_dev(struct net_device *dev,
int (*fn)(struct net_device *dev,
void *data),
void *data)
{
struct net_device *ldev;
struct list_head *iter;
int ret;

for (iter = &dev->adj_list.lower,
ldev = netdev_next_lower_dev(dev, &iter);
ldev;
ldev = netdev_next_lower_dev(dev, &iter)) {
/* first is the lower device itself */
ret = fn(ldev, data);
if (ret)
return ret;

/* then look at all of its lower devices */
ret = netdev_walk_all_lower_dev(ldev, fn, data);
if (ret)
return ret;
}

return 0;
}
EXPORT_SYMBOL_GPL(netdev_walk_all_lower_dev);

/**
* netdev_all_lower_get_next_rcu - Get the next device from all
* lower neighbour list, RCU variant
Expand All @@ -5382,6 +5495,48 @@ struct net_device *netdev_all_lower_get_next_rcu(struct net_device *dev,
}
EXPORT_SYMBOL(netdev_all_lower_get_next_rcu);

static struct net_device *netdev_next_lower_dev_rcu(struct net_device *dev,
struct list_head **iter)
{
struct netdev_adjacent *lower;

lower = list_entry_rcu((*iter)->next, struct netdev_adjacent, list);
if (&lower->list == &dev->adj_list.lower)
return NULL;

*iter = &lower->list;

return lower->dev;
}

int netdev_walk_all_lower_dev_rcu(struct net_device *dev,
int (*fn)(struct net_device *dev,
void *data),
void *data)
{
struct net_device *ldev;
struct list_head *iter;
int ret;

for (iter = &dev->adj_list.lower,
ldev = netdev_next_lower_dev_rcu(dev, &iter);
ldev;
ldev = netdev_next_lower_dev_rcu(dev, &iter)) {
/* first is the lower device itself */
ret = fn(ldev, data);
if (ret)
return ret;

/* then look at all of its lower devices */
ret = netdev_walk_all_lower_dev_rcu(ldev, fn, data);
if (ret)
return ret;
}

return 0;
}
EXPORT_SYMBOL_GPL(netdev_walk_all_lower_dev_rcu);

/**
* netdev_lower_get_first_private_rcu - Get the first ->private from the
* lower neighbour list, RCU
Expand Down

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