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authorJason Gunthorpe <jgg@mellanox.com>2019-02-12 21:12:51 -0700
committerJason Gunthorpe <jgg@mellanox.com>2019-02-19 20:52:18 -0700
commit324e227ea7c952626abafe72db42ae0d70220a6e (patch)
tree5e0a306788204bfb58ff927c18fb242e81daa1fc
parentRDMA/device: Add ib_device_set_netdev() as an alternative to get_netdev (diff)
downloadlinux-dev-324e227ea7c952626abafe72db42ae0d70220a6e.tar.xz
linux-dev-324e227ea7c952626abafe72db42ae0d70220a6e.zip
RDMA/device: Add ib_device_get_by_netdev()
Several drivers need to find the ib_device from a given netdev. rxe needs this at speed in an unsleepable context, so choose to implement the translation using a RCU safe hash table. The hash table can have a many to one mapping. This is intended to support some future case where multiple IB drivers (ie iWarp and RoCE) connect to the same netdevs. driver_ids will need to be different to support this. In the process this makes the struct ib_device and ib_port_data RCU safe by deferring their kfrees. Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
-rw-r--r--drivers/infiniband/core/device.c119
-rw-r--r--include/rdma/ib_verbs.h10
2 files changed, 116 insertions, 13 deletions
diff --git a/drivers/infiniband/core/device.c b/drivers/infiniband/core/device.c
index 7680a64a98bc..f6795ad7ca98 100644
--- a/drivers/infiniband/core/device.c
+++ b/drivers/infiniband/core/device.c
@@ -40,6 +40,7 @@
#include <linux/netdevice.h>
#include <linux/security.h>
#include <linux/notifier.h>
+#include <linux/hashtable.h>
#include <rdma/rdma_netlink.h>
#include <rdma/ib_addr.h>
#include <rdma/ib_cache.h>
@@ -134,6 +135,10 @@ static void *xan_find_marked(struct xarray *xa, unsigned long *indexp,
!xa_is_err(entry); \
(index)++, entry = xan_find_marked(xa, &(index), filter))
+/* RCU hash table mapping netdevice pointers to struct ib_port_data */
+static DEFINE_SPINLOCK(ndev_hash_lock);
+static DECLARE_HASHTABLE(ndev_hash, 5);
+
static void free_netdevs(struct ib_device *ib_dev);
static int ib_security_change(struct notifier_block *nb, unsigned long event,
void *lsm_data);
@@ -144,6 +149,12 @@ static struct notifier_block ibdev_lsm_nb = {
.notifier_call = ib_security_change,
};
+/* Pointer to the RCU head at the start of the ib_port_data array */
+struct ib_port_data_rcu {
+ struct rcu_head rcu_head;
+ struct ib_port_data pdata[];
+};
+
static int ib_device_check_mandatory(struct ib_device *device)
{
#define IB_MANDATORY_FUNC(x) { offsetof(struct ib_device_ops, x), #x }
@@ -295,9 +306,12 @@ static void ib_device_release(struct device *device)
WARN_ON(refcount_read(&dev->refcount));
ib_cache_release_one(dev);
ib_security_release_port_pkey_list(dev);
- kfree(dev->port_data);
xa_destroy(&dev->client_data);
- kfree(dev);
+ if (dev->port_data)
+ kfree_rcu(container_of(dev->port_data, struct ib_port_data_rcu,
+ pdata[0]),
+ rcu_head);
+ kfree_rcu(dev, rcu_head);
}
static int ib_device_uevent(struct device *device,
@@ -468,6 +482,7 @@ static void remove_client_context(struct ib_device *device,
static int alloc_port_data(struct ib_device *device)
{
+ struct ib_port_data_rcu *pdata_rcu;
unsigned int port;
if (device->port_data)
@@ -484,17 +499,26 @@ static int alloc_port_data(struct ib_device *device)
* Therefore port_data is declared as a 1 based array with potential
* empty slots at the beginning.
*/
- device->port_data = kcalloc(rdma_end_port(device) + 1,
- sizeof(*device->port_data), GFP_KERNEL);
- if (!device->port_data)
+ pdata_rcu = kzalloc(struct_size(pdata_rcu, pdata,
+ rdma_end_port(device) + 1),
+ GFP_KERNEL);
+ if (!pdata_rcu)
return -ENOMEM;
+ /*
+ * The rcu_head is put in front of the port data array and the stored
+ * pointer is adjusted since we never need to see that member until
+ * kfree_rcu.
+ */
+ device->port_data = pdata_rcu->pdata;
rdma_for_each_port (device, port) {
struct ib_port_data *pdata = &device->port_data[port];
+ pdata->ib_dev = device;
spin_lock_init(&pdata->pkey_list_lock);
INIT_LIST_HEAD(&pdata->pkey_list);
spin_lock_init(&pdata->netdev_lock);
+ INIT_HLIST_NODE(&pdata->ndev_hash_link);
}
return 0;
}
@@ -1042,6 +1066,29 @@ int ib_query_port(struct ib_device *device,
}
EXPORT_SYMBOL(ib_query_port);
+static void add_ndev_hash(struct ib_port_data *pdata)
+{
+ unsigned long flags;
+
+ might_sleep();
+
+ spin_lock_irqsave(&ndev_hash_lock, flags);
+ if (hash_hashed(&pdata->ndev_hash_link)) {
+ hash_del_rcu(&pdata->ndev_hash_link);
+ spin_unlock_irqrestore(&ndev_hash_lock, flags);
+ /*
+ * We cannot do hash_add_rcu after a hash_del_rcu until the
+ * grace period
+ */
+ synchronize_rcu();
+ spin_lock_irqsave(&ndev_hash_lock, flags);
+ }
+ if (pdata->netdev)
+ hash_add_rcu(ndev_hash, &pdata->ndev_hash_link,
+ (uintptr_t)pdata->netdev);
+ spin_unlock_irqrestore(&ndev_hash_lock, flags);
+}
+
/**
* ib_device_set_netdev - Associate the ib_dev with an underlying net_device
* @ib_dev: Device to modify
@@ -1078,17 +1125,19 @@ int ib_device_set_netdev(struct ib_device *ib_dev, struct net_device *ndev,
pdata = &ib_dev->port_data[port];
spin_lock_irqsave(&pdata->netdev_lock, flags);
- if (pdata->netdev == ndev) {
+ old_ndev = rcu_dereference_protected(
+ pdata->netdev, lockdep_is_held(&pdata->netdev_lock));
+ if (old_ndev == ndev) {
spin_unlock_irqrestore(&pdata->netdev_lock, flags);
return 0;
}
- old_ndev = pdata->netdev;
if (ndev)
dev_hold(ndev);
- pdata->netdev = ndev;
+ rcu_assign_pointer(pdata->netdev, ndev);
spin_unlock_irqrestore(&pdata->netdev_lock, flags);
+ add_ndev_hash(pdata);
if (old_ndev)
dev_put(old_ndev);
@@ -1103,11 +1152,24 @@ static void free_netdevs(struct ib_device *ib_dev)
rdma_for_each_port (ib_dev, port) {
struct ib_port_data *pdata = &ib_dev->port_data[port];
+ struct net_device *ndev;
spin_lock_irqsave(&pdata->netdev_lock, flags);
- if (pdata->netdev) {
- dev_put(pdata->netdev);
- pdata->netdev = NULL;
+ ndev = rcu_dereference_protected(
+ pdata->netdev, lockdep_is_held(&pdata->netdev_lock));
+ if (ndev) {
+ spin_lock(&ndev_hash_lock);
+ hash_del_rcu(&pdata->ndev_hash_link);
+ spin_unlock(&ndev_hash_lock);
+
+ /*
+ * If this is the last dev_put there is still a
+ * synchronize_rcu before the netdev is kfreed, so we
+ * can continue to rely on unlocked pointer
+ * comparisons after the put
+ */
+ rcu_assign_pointer(pdata->netdev, NULL);
+ dev_put(ndev);
}
spin_unlock_irqrestore(&pdata->netdev_lock, flags);
}
@@ -1132,7 +1194,8 @@ struct net_device *ib_device_get_netdev(struct ib_device *ib_dev,
res = ib_dev->ops.get_netdev(ib_dev, port);
else {
spin_lock(&pdata->netdev_lock);
- res = pdata->netdev;
+ res = rcu_dereference_protected(
+ pdata->netdev, lockdep_is_held(&pdata->netdev_lock));
if (res)
dev_hold(res);
spin_unlock(&pdata->netdev_lock);
@@ -1151,6 +1214,38 @@ struct net_device *ib_device_get_netdev(struct ib_device *ib_dev,
}
/**
+ * ib_device_get_by_netdev - Find an IB device associated with a netdev
+ * @ndev: netdev to locate
+ * @driver_id: The driver ID that must match (RDMA_DRIVER_UNKNOWN matches all)
+ *
+ * Find and hold an ib_device that is associated with a netdev via
+ * ib_device_set_netdev(). The caller must call ib_device_put() on the
+ * returned pointer.
+ */
+struct ib_device *ib_device_get_by_netdev(struct net_device *ndev,
+ enum rdma_driver_id driver_id)
+{
+ struct ib_device *res = NULL;
+ struct ib_port_data *cur;
+
+ rcu_read_lock();
+ hash_for_each_possible_rcu (ndev_hash, cur, ndev_hash_link,
+ (uintptr_t)ndev) {
+ if (rcu_access_pointer(cur->netdev) == ndev &&
+ (driver_id == RDMA_DRIVER_UNKNOWN ||
+ cur->ib_dev->driver_id == driver_id) &&
+ ib_device_try_get(cur->ib_dev)) {
+ res = cur->ib_dev;
+ break;
+ }
+ }
+ rcu_read_unlock();
+
+ return res;
+}
+EXPORT_SYMBOL(ib_device_get_by_netdev);
+
+/**
* ib_enum_roce_netdev - enumerate all RoCE ports
* @ib_dev : IB device we want to query
* @filter: Should we call the callback?
diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index 7f81a313c01b..3aa802b65cf3 100644
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -2198,6 +2198,8 @@ struct ib_port_immutable {
};
struct ib_port_data {
+ struct ib_device *ib_dev;
+
struct ib_port_immutable immutable;
spinlock_t pkey_list_lock;
@@ -2206,7 +2208,8 @@ struct ib_port_data {
struct ib_port_cache cache;
spinlock_t netdev_lock;
- struct net_device *netdev;
+ struct net_device __rcu *netdev;
+ struct hlist_node ndev_hash_link;
};
/* rdma netdev type - specifies protocol type */
@@ -2545,6 +2548,7 @@ struct ib_device {
struct device *dma_device;
struct ib_device_ops ops;
char name[IB_DEVICE_NAME_MAX];
+ struct rcu_head rcu_head;
struct list_head event_handler_list;
spinlock_t event_handler_lock;
@@ -3996,6 +4000,10 @@ static inline bool ib_device_try_get(struct ib_device *dev)
}
void ib_device_put(struct ib_device *device);
+struct ib_device *ib_device_get_by_netdev(struct net_device *ndev,
+ enum rdma_driver_id driver_id);
+struct ib_device *ib_device_get_by_name(const char *name,
+ enum rdma_driver_id driver_id);
struct net_device *ib_get_net_dev_by_params(struct ib_device *dev, u8 port,
u16 pkey, const union ib_gid *gid,
const struct sockaddr *addr);