[patch net-next v4 00/10] ipv4: fib: Replay events when registering FIB notifier

[patch net-next v4 00/10] ipv4: fib: Replay events when registering FIB notifier

[Jiri Pirko]

From: Jiri Pirko <jiri@mellanox.com>

Ido says:

In kernel 4.9 the switchdev-specific FIB offload mechanism was replaced
by a new FIB notification chain to which modules could register in order
to be notified about the addition and deletion of FIB entries. The
motivation for this change was that switchdev drivers need to be able to
reflect the entire FIB table and not only FIBs configured on top of the
port netdevs themselves. This is useful in case of in-band management.

The fundamental problem with this approach is that upon registration
listeners lose all the information previously sent in the chain and
thus have an incomplete view of the FIB tables, which can result in
packet loss. This patchset fixes that by dumping the FIB tables and
replaying notifications previously sent in the chain for the registered
notification block.

The entire dump process is done under RCU and thus the FIB notification
chain is converted to be atomic. The listeners are modified accordingly.
This is done in the first eight patches.

The ninth patch adds a change sequence counter to ensure the integrity
of the FIB dump. The last patch adds the dump itself to the FIB chain
registration function and modifies existing listeners to pass a callback
to be executed in case dump was inconsistent.

---
v3->v4:
- Register the notification block after the dump and protect it using
  the change sequence counter (Hannes Frederic Sowa).
- Since we now integrate the dump into the registration function, drop
  the sysctl to set maximum number of retries and instead set it to a
  fixed number. Lets see if it's really a problem before adding something
  we can never remove.
- For the same reason, dump FIB tables for all net namespaces.
- Add a comment regarding guarantees provided by mutex semantics.

v2->v3:
- Add sysctl to set the number of FIB dump retries (Hannes Frederic Sowa).
- Read the sequence counter under RTNL to ensure synchronization
  between the dump process and other processes changing the routing
  tables (Hannes Frederic Sowa).
- Pass a callback to the dump function to be executed prior to a retry.
- Limit the dump to a single net namespace.

v1->v2:
- Add a sequence counter to ensure the integrity of the FIB dump
  (David S. Miller, Hannes Frederic Sowa).
- Protect notifications from re-ordering in listeners by using an
  ordered workqueue (Hannes Frederic Sowa).
- Introduce fib_info_hold() (Jiri Pirko).
- Relieve rocker from the need to invoke the FIB dump by registering
  to the FIB notification chain prior to ports creation.

Ido Schimmel (10):
  ipv4: fib: Export free_fib_info()
  ipv4: fib: Add fib_info_hold() helper
  mlxsw: core: Create an ordered workqueue for FIB offload
  mlxsw: spectrum_router: Implement FIB offload in deferred work
  rocker: Create an ordered workqueue for FIB offload
  rocker: Implement FIB offload in deferred work
  rocker: Register FIB notifier before creating ports
  ipv4: fib: Convert FIB notification chain to be atomic
  ipv4: fib: Allow for consistent FIB dumping
  ipv4: fib: Replay events when registering FIB notifier

 drivers/net/ethernet/mellanox/mlxsw/core.c         |  22 +++
 drivers/net/ethernet/mellanox/mlxsw/core.h         |   2 +
 .../net/ethernet/mellanox/mlxsw/spectrum_router.c  |  92 ++++++++++--
 drivers/net/ethernet/rocker/rocker.h               |   1 +
 drivers/net/ethernet/rocker/rocker_main.c          |  84 +++++++++--
 drivers/net/ethernet/rocker/rocker_ofdpa.c         |   1 +
 include/net/ip_fib.h                               |   8 +-
 include/net/netns/ipv4.h                           |   3 +
 net/ipv4/fib_frontend.c                            |   2 +
 net/ipv4/fib_semantics.c                           |   1 +
 net/ipv4/fib_trie.c                                | 155 ++++++++++++++++++++-
 11 files changed, 342 insertions(+), 29 deletions(-)

-- 
2.7.4

[patch net-next v4 01/10] ipv4: fib: Export free_fib_info()

[Jiri Pirko]

From: Ido Schimmel <idosch@mellanox.com>

The FIB notification chain is going to be converted to an atomic chain,
which means switchdev drivers will have to offload FIB entries in
deferred work, as hardware operations entail sleeping.

However, while the work is queued fib info might be freed, so a
reference must be taken. To release the reference (and potentially free
the fib info) fib_info_put() will be called, which in turn calls
free_fib_info().

Export free_fib_info() so that modules will be able to invoke
fib_info_put().

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
---
 net/ipv4/fib_semantics.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index 388d3e2..c1bc1e9 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -234,6 +234,7 @@ void free_fib_info(struct fib_info *fi)
 #endif
 	call_rcu(&fi->rcu, free_fib_info_rcu);
 }
+EXPORT_SYMBOL_GPL(free_fib_info);
 
 void fib_release_info(struct fib_info *fi)
 {
-- 
2.7.4

[patch net-next v4 02/10] ipv4: fib: Add fib_info_hold() helper

[Jiri Pirko]

From: Ido Schimmel <idosch@mellanox.com>

As explained in the previous commit, modules are going to need to take a
reference on fib info and then drop it using fib_info_put().

Add the fib_info_hold() helper to make the code more readable and also
symmetric with fib_info_put().

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Suggested-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
---
 include/net/ip_fib.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/include/net/ip_fib.h b/include/net/ip_fib.h
index f390c3b..6c67b93 100644
--- a/include/net/ip_fib.h
+++ b/include/net/ip_fib.h
@@ -397,6 +397,11 @@ static inline void fib_combine_itag(u32 *itag, const struct fib_result *res)
 
 void free_fib_info(struct fib_info *fi);
 
+static inline void fib_info_hold(struct fib_info *fi)
+{
+	atomic_inc(&fi->fib_clntref);
+}
+
 static inline void fib_info_put(struct fib_info *fi)
 {
 	if (atomic_dec_and_test(&fi->fib_clntref))
-- 
2.7.4

[patch net-next v4 03/10] mlxsw: core: Create an ordered workqueue for FIB offload

[Jiri Pirko]

From: Ido Schimmel <idosch@mellanox.com>

We're going to start processing FIB entries addition / deletion events
in deferred work. These work items must be processed in the order they
were submitted or otherwise we can have differences between the kernel's
FIB table and the device's.

Solve this by creating an ordered workqueue to which these work items
will be submitted to. Note that we can't simply convert the current
workqueue to be ordered, as EMADs re-transmissions are also processed in
deferred work.

Later on, we can migrate other work items to this workqueue, such as FDB
notification processing and nexthop resolution, since they all take the
same lock anyway.

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
---
 drivers/net/ethernet/mellanox/mlxsw/core.c | 22 ++++++++++++++++++++++
 drivers/net/ethernet/mellanox/mlxsw/core.h |  2 ++
 2 files changed, 24 insertions(+)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/core.c b/drivers/net/ethernet/mellanox/mlxsw/core.c
index 4dc028b..57a9884 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/core.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/core.c
@@ -77,6 +77,7 @@ static const char mlxsw_core_driver_name[] = "mlxsw_core";
 static struct dentry *mlxsw_core_dbg_root;
 
 static struct workqueue_struct *mlxsw_wq;
+static struct workqueue_struct *mlxsw_owq;
 
 struct mlxsw_core_pcpu_stats {
 	u64			trap_rx_packets[MLXSW_TRAP_ID_MAX];
@@ -1900,6 +1901,18 @@ int mlxsw_core_schedule_dw(struct delayed_work *dwork, unsigned long delay)
 }
 EXPORT_SYMBOL(mlxsw_core_schedule_dw);
 
+int mlxsw_core_schedule_odw(struct delayed_work *dwork, unsigned long delay)
+{
+	return queue_delayed_work(mlxsw_owq, dwork, delay);
+}
+EXPORT_SYMBOL(mlxsw_core_schedule_odw);
+
+void mlxsw_core_flush_owq(void)
+{
+	flush_workqueue(mlxsw_owq);
+}
+EXPORT_SYMBOL(mlxsw_core_flush_owq);
+
 static int __init mlxsw_core_module_init(void)
 {
 	int err;
@@ -1907,6 +1920,12 @@ static int __init mlxsw_core_module_init(void)
 	mlxsw_wq = alloc_workqueue(mlxsw_core_driver_name, WQ_MEM_RECLAIM, 0);
 	if (!mlxsw_wq)
 		return -ENOMEM;
+	mlxsw_owq = alloc_ordered_workqueue("%s_ordered", WQ_MEM_RECLAIM,
+					    mlxsw_core_driver_name);
+	if (!mlxsw_owq) {
+		err = -ENOMEM;
+		goto err_alloc_ordered_workqueue;
+	}
 	mlxsw_core_dbg_root = debugfs_create_dir(mlxsw_core_driver_name, NULL);
 	if (!mlxsw_core_dbg_root) {
 		err = -ENOMEM;
@@ -1915,6 +1934,8 @@ static int __init mlxsw_core_module_init(void)
 	return 0;
 
 err_debugfs_create_dir:
+	destroy_workqueue(mlxsw_owq);
+err_alloc_ordered_workqueue:
 	destroy_workqueue(mlxsw_wq);
 	return err;
 }
@@ -1922,6 +1943,7 @@ static int __init mlxsw_core_module_init(void)
 static void __exit mlxsw_core_module_exit(void)
 {
 	debugfs_remove_recursive(mlxsw_core_dbg_root);
+	destroy_workqueue(mlxsw_owq);
 	destroy_workqueue(mlxsw_wq);
 }
 
diff --git a/drivers/net/ethernet/mellanox/mlxsw/core.h b/drivers/net/ethernet/mellanox/mlxsw/core.h
index e856b49..a7f94fb 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/core.h
+++ b/drivers/net/ethernet/mellanox/mlxsw/core.h
@@ -207,6 +207,8 @@ enum devlink_port_type mlxsw_core_port_type_get(struct mlxsw_core *mlxsw_core,
 						u8 local_port);
 
 int mlxsw_core_schedule_dw(struct delayed_work *dwork, unsigned long delay);
+int mlxsw_core_schedule_odw(struct delayed_work *dwork, unsigned long delay);
+void mlxsw_core_flush_owq(void);
 
 #define MLXSW_CONFIG_PROFILE_SWID_COUNT 8
 
-- 
2.7.4

[patch net-next v4 04/10] mlxsw: spectrum_router: Implement FIB offload in deferred work

[Jiri Pirko]

From: Ido Schimmel <idosch@mellanox.com>

FIB offload is currently done in process context with RTNL held, but
we're about to dump the FIB tables in RCU critical section, so we can no
longer sleep.

Instead, defer the operation to process context using deferred work. Make
sure fib info isn't freed while the work is queued by taking a reference
on it and releasing it after the operation is done.

Deferring the operation is valid because the upper layers always assume
the operation was successful. If it's not, then the driver-specific
abort mechanism is called and all routed traffic is directed to slow
path.

The work items are submitted to an ordered workqueue to prevent a
mismatch between the kernel's FIB table and the device's.

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
---
 .../net/ethernet/mellanox/mlxsw/spectrum_router.c  | 72 +++++++++++++++++++---
 1 file changed, 62 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
index 683f045..14bed1d 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
@@ -593,6 +593,14 @@ static void mlxsw_sp_router_fib_flush(struct mlxsw_sp *mlxsw_sp);
 
 static void mlxsw_sp_vrs_fini(struct mlxsw_sp *mlxsw_sp)
 {
+	/* At this stage we're guaranteed not to have new incoming
+	 * FIB notifications and the work queue is free from FIBs
+	 * sitting on top of mlxsw netdevs. However, we can still
+	 * have other FIBs queued. Flush the queue before flushing
+	 * the device's tables. No need for locks, as we're the only
+	 * writer.
+	 */
+	mlxsw_core_flush_owq();
 	mlxsw_sp_router_fib_flush(mlxsw_sp);
 	kfree(mlxsw_sp->router.vrs);
 }
@@ -1948,30 +1956,74 @@ static void __mlxsw_sp_router_fini(struct mlxsw_sp *mlxsw_sp)
 	kfree(mlxsw_sp->rifs);
 }
 
-static int mlxsw_sp_router_fib_event(struct notifier_block *nb,
-				     unsigned long event, void *ptr)
+struct mlxsw_sp_fib_event_work {
+	struct delayed_work dw;
+	struct fib_entry_notifier_info fen_info;
+	struct mlxsw_sp *mlxsw_sp;
+	unsigned long event;
+};
+
+static void mlxsw_sp_router_fib_event_work(struct work_struct *work)
 {
-	struct mlxsw_sp *mlxsw_sp = container_of(nb, struct mlxsw_sp, fib_nb);
-	struct fib_entry_notifier_info *fen_info = ptr;
+	struct mlxsw_sp_fib_event_work *fib_work =
+		container_of(work, struct mlxsw_sp_fib_event_work, dw.work);
+	struct mlxsw_sp *mlxsw_sp = fib_work->mlxsw_sp;
 	int err;
 
-	if (!net_eq(fen_info->info.net, &init_net))
-		return NOTIFY_DONE;
-
-	switch (event) {
+	/* Protect internal structures from changes */
+	rtnl_lock();
+	switch (fib_work->event) {
 	case FIB_EVENT_ENTRY_ADD:
-		err = mlxsw_sp_router_fib4_add(mlxsw_sp, fen_info);
+		err = mlxsw_sp_router_fib4_add(mlxsw_sp, &fib_work->fen_info);
 		if (err)
 			mlxsw_sp_router_fib4_abort(mlxsw_sp);
+		fib_info_put(fib_work->fen_info.fi);
 		break;
 	case FIB_EVENT_ENTRY_DEL:
-		mlxsw_sp_router_fib4_del(mlxsw_sp, fen_info);
+		mlxsw_sp_router_fib4_del(mlxsw_sp, &fib_work->fen_info);
+		fib_info_put(fib_work->fen_info.fi);
 		break;
 	case FIB_EVENT_RULE_ADD: /* fall through */
 	case FIB_EVENT_RULE_DEL:
 		mlxsw_sp_router_fib4_abort(mlxsw_sp);
 		break;
 	}
+	rtnl_unlock();
+	kfree(fib_work);
+}
+
+/* Called with rcu_read_lock() */
+static int mlxsw_sp_router_fib_event(struct notifier_block *nb,
+				     unsigned long event, void *ptr)
+{
+	struct mlxsw_sp *mlxsw_sp = container_of(nb, struct mlxsw_sp, fib_nb);
+	struct mlxsw_sp_fib_event_work *fib_work;
+	struct fib_notifier_info *info = ptr;
+
+	if (!net_eq(info->net, &init_net))
+		return NOTIFY_DONE;
+
+	fib_work = kzalloc(sizeof(*fib_work), GFP_ATOMIC);
+	if (WARN_ON(!fib_work))
+		return NOTIFY_BAD;
+
+	INIT_DELAYED_WORK(&fib_work->dw, mlxsw_sp_router_fib_event_work);
+	fib_work->mlxsw_sp = mlxsw_sp;
+	fib_work->event = event;
+
+	switch (event) {
+	case FIB_EVENT_ENTRY_ADD: /* fall through */
+	case FIB_EVENT_ENTRY_DEL:
+		memcpy(&fib_work->fen_info, ptr, sizeof(fib_work->fen_info));
+		/* Take referece on fib_info to prevent it from being
+		 * freed while work is queued. Release it afterwards.
+		 */
+		fib_info_hold(fib_work->fen_info.fi);
+		break;
+	}
+
+	mlxsw_core_schedule_odw(&fib_work->dw, 0);
+
 	return NOTIFY_DONE;
 }
 
-- 
2.7.4

[patch net-next v4 05/10] rocker: Create an ordered workqueue for FIB offload

[Jiri Pirko]

From: Ido Schimmel <idosch@mellanox.com>

As explained in the previous commits, we need to process FIB entries
addition / deletion events in FIFO order or otherwise we can have a
mismatch between the kernel's FIB table and the device's.

Create an ordered workqueue for rocker to which these work items will be
submitted to.

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
---
 drivers/net/ethernet/rocker/rocker.h      |  1 +
 drivers/net/ethernet/rocker/rocker_main.c | 11 +++++++++++
 2 files changed, 12 insertions(+)

diff --git a/drivers/net/ethernet/rocker/rocker.h b/drivers/net/ethernet/rocker/rocker.h
index 2eb9b49..ee9675d 100644
--- a/drivers/net/ethernet/rocker/rocker.h
+++ b/drivers/net/ethernet/rocker/rocker.h
@@ -72,6 +72,7 @@ struct rocker {
 	struct rocker_dma_ring_info event_ring;
 	struct notifier_block fib_nb;
 	struct rocker_world_ops *wops;
+	struct workqueue_struct *rocker_owq;
 	void *wpriv;
 };
 
diff --git a/drivers/net/ethernet/rocker/rocker_main.c b/drivers/net/ethernet/rocker/rocker_main.c
index 67df4cf..424be96 100644
--- a/drivers/net/ethernet/rocker/rocker_main.c
+++ b/drivers/net/ethernet/rocker/rocker_main.c
@@ -28,6 +28,7 @@
 #include <linux/if_bridge.h>
 #include <linux/bitops.h>
 #include <linux/ctype.h>
+#include <linux/workqueue.h>
 #include <net/switchdev.h>
 #include <net/rtnetlink.h>
 #include <net/netevent.h>
@@ -2754,6 +2755,13 @@ static int rocker_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 		goto err_request_event_irq;
 	}
 
+	rocker->rocker_owq = alloc_ordered_workqueue(rocker_driver_name,
+						     WQ_MEM_RECLAIM);
+	if (!rocker->rocker_owq) {
+		err = -ENOMEM;
+		goto err_alloc_ordered_workqueue;
+	}
+
 	rocker->hw.id = rocker_read64(rocker, SWITCH_ID);
 
 	err = rocker_probe_ports(rocker);
@@ -2771,6 +2779,8 @@ static int rocker_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	return 0;
 
 err_probe_ports:
+	destroy_workqueue(rocker->rocker_owq);
+err_alloc_ordered_workqueue:
 	free_irq(rocker_msix_vector(rocker, ROCKER_MSIX_VEC_EVENT), rocker);
 err_request_event_irq:
 	free_irq(rocker_msix_vector(rocker, ROCKER_MSIX_VEC_CMD), rocker);
@@ -2799,6 +2809,7 @@ static void rocker_remove(struct pci_dev *pdev)
 	unregister_fib_notifier(&rocker->fib_nb);
 	rocker_write32(rocker, CONTROL, ROCKER_CONTROL_RESET);
 	rocker_remove_ports(rocker);
+	destroy_workqueue(rocker->rocker_owq);
 	free_irq(rocker_msix_vector(rocker, ROCKER_MSIX_VEC_EVENT), rocker);
 	free_irq(rocker_msix_vector(rocker, ROCKER_MSIX_VEC_CMD), rocker);
 	rocker_dma_rings_fini(rocker);
-- 
2.7.4

[patch net-next v4 06/10] rocker: Implement FIB offload in deferred work

[Jiri Pirko]

From: Ido Schimmel <idosch@mellanox.com>

Convert rocker to offload FIBs in deferred work in a similar fashion to
mlxsw, which was converted in the previous commits.

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
---
 drivers/net/ethernet/rocker/rocker_main.c  | 58 +++++++++++++++++++++++++-----
 drivers/net/ethernet/rocker/rocker_ofdpa.c |  1 +
 2 files changed, 51 insertions(+), 8 deletions(-)

diff --git a/drivers/net/ethernet/rocker/rocker_main.c b/drivers/net/ethernet/rocker/rocker_main.c
index 424be96..914e9e1 100644
--- a/drivers/net/ethernet/rocker/rocker_main.c
+++ b/drivers/net/ethernet/rocker/rocker_main.c
@@ -2166,28 +2166,70 @@ static const struct switchdev_ops rocker_port_switchdev_ops = {
 	.switchdev_port_obj_dump	= rocker_port_obj_dump,
 };
 
-static int rocker_router_fib_event(struct notifier_block *nb,
-				   unsigned long event, void *ptr)
+struct rocker_fib_event_work {
+	struct work_struct work;
+	struct fib_entry_notifier_info fen_info;
+	struct rocker *rocker;
+	unsigned long event;
+};
+
+static void rocker_router_fib_event_work(struct work_struct *work)
 {
-	struct rocker *rocker = container_of(nb, struct rocker, fib_nb);
-	struct fib_entry_notifier_info *fen_info = ptr;
+	struct rocker_fib_event_work *fib_work =
+		container_of(work, struct rocker_fib_event_work, work);
+	struct rocker *rocker = fib_work->rocker;
 	int err;
 
-	switch (event) {
+	/* Protect internal structures from changes */
+	rtnl_lock();
+	switch (fib_work->event) {
 	case FIB_EVENT_ENTRY_ADD:
-		err = rocker_world_fib4_add(rocker, fen_info);
+		err = rocker_world_fib4_add(rocker, &fib_work->fen_info);
 		if (err)
 			rocker_world_fib4_abort(rocker);
-		else
+		fib_info_put(fib_work->fen_info.fi);
 		break;
 	case FIB_EVENT_ENTRY_DEL:
-		rocker_world_fib4_del(rocker, fen_info);
+		rocker_world_fib4_del(rocker, &fib_work->fen_info);
+		fib_info_put(fib_work->fen_info.fi);
 		break;
 	case FIB_EVENT_RULE_ADD: /* fall through */
 	case FIB_EVENT_RULE_DEL:
 		rocker_world_fib4_abort(rocker);
 		break;
 	}
+	rtnl_unlock();
+	kfree(fib_work);
+}
+
+/* Called with rcu_read_lock() */
+static int rocker_router_fib_event(struct notifier_block *nb,
+				   unsigned long event, void *ptr)
+{
+	struct rocker *rocker = container_of(nb, struct rocker, fib_nb);
+	struct rocker_fib_event_work *fib_work;
+
+	fib_work = kzalloc(sizeof(*fib_work), GFP_ATOMIC);
+	if (WARN_ON(!fib_work))
+		return NOTIFY_BAD;
+
+	INIT_WORK(&fib_work->work, rocker_router_fib_event_work);
+	fib_work->rocker = rocker;
+	fib_work->event = event;
+
+	switch (event) {
+	case FIB_EVENT_ENTRY_ADD: /* fall through */
+	case FIB_EVENT_ENTRY_DEL:
+		memcpy(&fib_work->fen_info, ptr, sizeof(fib_work->fen_info));
+		/* Take referece on fib_info to prevent it from being
+		 * freed while work is queued. Release it afterwards.
+		 */
+		fib_info_hold(fib_work->fen_info.fi);
+		break;
+	}
+
+	queue_work(rocker->rocker_owq, &fib_work->work);
+
 	return NOTIFY_DONE;
 }
 
diff --git a/drivers/net/ethernet/rocker/rocker_ofdpa.c b/drivers/net/ethernet/rocker/rocker_ofdpa.c
index 4ca4613..7cd76b6 100644
--- a/drivers/net/ethernet/rocker/rocker_ofdpa.c
+++ b/drivers/net/ethernet/rocker/rocker_ofdpa.c
@@ -2516,6 +2516,7 @@ static void ofdpa_fini(struct rocker *rocker)
 	int bkt;
 
 	del_timer_sync(&ofdpa->fdb_cleanup_timer);
+	flush_workqueue(rocker->rocker_owq);
 
 	spin_lock_irqsave(&ofdpa->flow_tbl_lock, flags);
 	hash_for_each_safe(ofdpa->flow_tbl, bkt, tmp, flow_entry, entry)
-- 
2.7.4

[patch net-next v4 07/10] rocker: Register FIB notifier before creating ports

[Jiri Pirko]

From: Ido Schimmel <idosch@mellanox.com>

We can miss FIB notifications sent between the time the ports were
created and the FIB notification block registered.

Instead of receiving these notifications only when they are replayed for
the FIB notification block during registration, just register the
notification block before the ports are created.

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
---
 drivers/net/ethernet/rocker/rocker_main.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/rocker/rocker_main.c b/drivers/net/ethernet/rocker/rocker_main.c
index 914e9e1..8c9c90a 100644
--- a/drivers/net/ethernet/rocker/rocker_main.c
+++ b/drivers/net/ethernet/rocker/rocker_main.c
@@ -2804,6 +2804,9 @@ static int rocker_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 		goto err_alloc_ordered_workqueue;
 	}
 
+	rocker->fib_nb.notifier_call = rocker_router_fib_event;
+	register_fib_notifier(&rocker->fib_nb);
+
 	rocker->hw.id = rocker_read64(rocker, SWITCH_ID);
 
 	err = rocker_probe_ports(rocker);
@@ -2812,15 +2815,13 @@ static int rocker_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 		goto err_probe_ports;
 	}
 
-	rocker->fib_nb.notifier_call = rocker_router_fib_event;
-	register_fib_notifier(&rocker->fib_nb);
-
 	dev_info(&pdev->dev, "Rocker switch with id %*phN\n",
 		 (int)sizeof(rocker->hw.id), &rocker->hw.id);
 
 	return 0;
 
 err_probe_ports:
+	unregister_fib_notifier(&rocker->fib_nb);
 	destroy_workqueue(rocker->rocker_owq);
 err_alloc_ordered_workqueue:
 	free_irq(rocker_msix_vector(rocker, ROCKER_MSIX_VEC_EVENT), rocker);
@@ -2848,9 +2849,9 @@ static void rocker_remove(struct pci_dev *pdev)
 {
 	struct rocker *rocker = pci_get_drvdata(pdev);
 
+	rocker_remove_ports(rocker);
 	unregister_fib_notifier(&rocker->fib_nb);
 	rocker_write32(rocker, CONTROL, ROCKER_CONTROL_RESET);
-	rocker_remove_ports(rocker);
 	destroy_workqueue(rocker->rocker_owq);
 	free_irq(rocker_msix_vector(rocker, ROCKER_MSIX_VEC_EVENT), rocker);
 	free_irq(rocker_msix_vector(rocker, ROCKER_MSIX_VEC_CMD), rocker);
-- 
2.7.4

[patch net-next v4 08/10] ipv4: fib: Convert FIB notification chain to be atomic

[Jiri Pirko]

From: Ido Schimmel <idosch@mellanox.com>

In order not to hold RTNL for long periods of time we're going to dump
the FIB tables using RCU.

Convert the FIB notification chain to be atomic, as we can't block in
RCU critical sections.

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
---
 net/ipv4/fib_trie.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index 026f309..9bfce0d 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -84,17 +84,17 @@
 #include <trace/events/fib.h>
 #include "fib_lookup.h"
 
-static BLOCKING_NOTIFIER_HEAD(fib_chain);
+static ATOMIC_NOTIFIER_HEAD(fib_chain);
 
 int register_fib_notifier(struct notifier_block *nb)
 {
-	return blocking_notifier_chain_register(&fib_chain, nb);
+	return atomic_notifier_chain_register(&fib_chain, nb);
 }
 EXPORT_SYMBOL(register_fib_notifier);
 
 int unregister_fib_notifier(struct notifier_block *nb)
 {
-	return blocking_notifier_chain_unregister(&fib_chain, nb);
+	return atomic_notifier_chain_unregister(&fib_chain, nb);
 }
 EXPORT_SYMBOL(unregister_fib_notifier);
 
@@ -102,7 +102,7 @@ int call_fib_notifiers(struct net *net, enum fib_event_type event_type,
 		       struct fib_notifier_info *info)
 {
 	info->net = net;
-	return blocking_notifier_call_chain(&fib_chain, event_type, info);
+	return atomic_notifier_call_chain(&fib_chain, event_type, info);
 }
 
 static int call_fib_entry_notifiers(struct net *net,
-- 
2.7.4

[patch net-next v4 09/10] ipv4: fib: Allow for consistent FIB dumping

[Jiri Pirko]

From: Ido Schimmel <idosch@mellanox.com>

The next patch will enable listeners of the FIB notification chain to
request a dump of the FIB tables. However, since RTNL isn't taken during
the dump, it's possible for the FIB tables to change mid-dump, which
will result in inconsistency between the listener's table and the
kernel's.

Allow listeners to know about changes that occurred mid-dump, by adding
a change sequence counter to each net namespace. The counter is
incremented just before a notification is sent in the FIB chain.

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
---
 include/net/netns/ipv4.h | 3 +++
 net/ipv4/fib_frontend.c  | 2 ++
 net/ipv4/fib_trie.c      | 1 +
 3 files changed, 6 insertions(+)

diff --git a/include/net/netns/ipv4.h b/include/net/netns/ipv4.h
index 7adf438..f0cf5a1 100644
--- a/include/net/netns/ipv4.h
+++ b/include/net/netns/ipv4.h
@@ -135,6 +135,9 @@ struct netns_ipv4 {
 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 	int sysctl_fib_multipath_use_neigh;
 #endif
+
+	unsigned int	fib_seq;	/* protected by rtnl_mutex */
+
 	atomic_t	rt_genid;
 };
 #endif
diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index 121384b..dbad5a1 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -1219,6 +1219,8 @@ static int __net_init ip_fib_net_init(struct net *net)
 	int err;
 	size_t size = sizeof(struct hlist_head) * FIB_TABLE_HASHSZ;
 
+	net->ipv4.fib_seq = 0;
+
 	/* Avoid false sharing : Use at least a full cache line */
 	size = max_t(size_t, size, L1_CACHE_BYTES);
 
diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index 9bfce0d..2891356 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -101,6 +101,7 @@ EXPORT_SYMBOL(unregister_fib_notifier);
 int call_fib_notifiers(struct net *net, enum fib_event_type event_type,
 		       struct fib_notifier_info *info)
 {
+	net->ipv4.fib_seq++;
 	info->net = net;
 	return atomic_notifier_call_chain(&fib_chain, event_type, info);
 }
-- 
2.7.4

[patch net-next v4 10/10] ipv4: fib: Replay events when registering FIB notifier

[Jiri Pirko]

From: Ido Schimmel <idosch@mellanox.com>

Commit b90eb7549499 ("fib: introduce FIB notification infrastructure")
introduced a new notification chain to notify listeners (f.e., switchdev
drivers) about addition and deletion of routes.

However, upon registration to the chain the FIB tables can already be
populated, which means potential listeners will have an incomplete view
of the tables.

Solve that by dumping the FIB tables and replaying the events to the
passed notification block. The dump itself is done using RCU in order
not to starve consumers that need RTNL to make progress.

The integrity of the dump is ensured by reading the FIB change sequence
counter before and after the dump under RTNL. This allows us to avoid
the problematic situation in which the dumping process sends a ENTRY_ADD
notification following ENTRY_DEL generated by another process holding
RTNL.

Callers of the registration function may pass a callback that is
executed in case the dump was inconsistent with current FIB tables.

The number of retries until a consistent dump is achieved is set to a
fixed number to prevent callers from looping for long periods of time.
In case current limit proves to be problematic in the future, it can be
easily converted to be configurable using a sysctl.

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
---
 .../net/ethernet/mellanox/mlxsw/spectrum_router.c  |  20 ++-
 drivers/net/ethernet/rocker/rocker_main.c          |   8 +-
 include/net/ip_fib.h                               |   3 +-
 net/ipv4/fib_trie.c                                | 148 ++++++++++++++++++++-
 4 files changed, 174 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
index 14bed1d..53126bf 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
@@ -2027,6 +2027,18 @@ static int mlxsw_sp_router_fib_event(struct notifier_block *nb,
 	return NOTIFY_DONE;
 }
 
+static void mlxsw_sp_router_fib_dump_flush(struct notifier_block *nb)
+{
+	struct mlxsw_sp *mlxsw_sp = container_of(nb, struct mlxsw_sp, fib_nb);
+
+	/* Flush pending FIB notifications and then flush the device's
+	 * table before requesting another dump. The FIB notification
+	 * block is unregistered, so no need to take RTNL.
+	 */
+	mlxsw_core_flush_owq();
+	mlxsw_sp_router_fib_flush(mlxsw_sp);
+}
+
 int mlxsw_sp_router_init(struct mlxsw_sp *mlxsw_sp)
 {
 	int err;
@@ -2047,9 +2059,15 @@ int mlxsw_sp_router_init(struct mlxsw_sp *mlxsw_sp)
 		goto err_neigh_init;
 
 	mlxsw_sp->fib_nb.notifier_call = mlxsw_sp_router_fib_event;
-	register_fib_notifier(&mlxsw_sp->fib_nb);
+	err = register_fib_notifier(&mlxsw_sp->fib_nb,
+				    mlxsw_sp_router_fib_dump_flush);
+	if (err)
+		goto err_register_fib_notifier;
+
 	return 0;
 
+err_register_fib_notifier:
+	mlxsw_sp_neigh_fini(mlxsw_sp);
 err_neigh_init:
 	mlxsw_sp_vrs_fini(mlxsw_sp);
 err_vrs_init:
diff --git a/drivers/net/ethernet/rocker/rocker_main.c b/drivers/net/ethernet/rocker/rocker_main.c
index 8c9c90a..7c450b5 100644
--- a/drivers/net/ethernet/rocker/rocker_main.c
+++ b/drivers/net/ethernet/rocker/rocker_main.c
@@ -2804,8 +2804,13 @@ static int rocker_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 		goto err_alloc_ordered_workqueue;
 	}
 
+	/* Only FIBs pointing to our own netdevs are programmed into
+	 * the device, so no need to pass a callback.
+	 */
 	rocker->fib_nb.notifier_call = rocker_router_fib_event;
-	register_fib_notifier(&rocker->fib_nb);
+	err = register_fib_notifier(&rocker->fib_nb, NULL);
+	if (err)
+		goto err_register_fib_notifier;
 
 	rocker->hw.id = rocker_read64(rocker, SWITCH_ID);
 
@@ -2822,6 +2827,7 @@ static int rocker_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 
 err_probe_ports:
 	unregister_fib_notifier(&rocker->fib_nb);
+err_register_fib_notifier:
 	destroy_workqueue(rocker->rocker_owq);
 err_alloc_ordered_workqueue:
 	free_irq(rocker_msix_vector(rocker, ROCKER_MSIX_VEC_EVENT), rocker);
diff --git a/include/net/ip_fib.h b/include/net/ip_fib.h
index 6c67b93..5f376af 100644
--- a/include/net/ip_fib.h
+++ b/include/net/ip_fib.h
@@ -221,7 +221,8 @@ enum fib_event_type {
 	FIB_EVENT_RULE_DEL,
 };
 
-int register_fib_notifier(struct notifier_block *nb);
+int register_fib_notifier(struct notifier_block *nb,
+			  void (*cb)(struct notifier_block *nb));
 int unregister_fib_notifier(struct notifier_block *nb);
 int call_fib_notifiers(struct net *net, enum fib_event_type event_type,
 		       struct fib_notifier_info *info);
diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index 2891356..73a6270 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -84,11 +84,99 @@
 #include <trace/events/fib.h>
 #include "fib_lookup.h"
 
+static unsigned int fib_seq_sum(void)
+{
+	unsigned int fib_seq = 0;
+	struct net *net;
+
+	rtnl_lock();
+	for_each_net(net)
+		fib_seq += net->ipv4.fib_seq;
+	rtnl_unlock();
+
+	return fib_seq;
+}
+
 static ATOMIC_NOTIFIER_HEAD(fib_chain);
 
-int register_fib_notifier(struct notifier_block *nb)
+static int call_fib_notifier(struct notifier_block *nb, struct net *net,
+			     enum fib_event_type event_type,
+			     struct fib_notifier_info *info)
 {
-	return atomic_notifier_chain_register(&fib_chain, nb);
+	info->net = net;
+	return nb->notifier_call(nb, event_type, info);
+}
+
+static void fib_rules_notify(struct net *net, struct notifier_block *nb,
+			     enum fib_event_type event_type)
+{
+#ifdef CONFIG_IP_MULTIPLE_TABLES
+	struct fib_notifier_info info;
+
+	if (net->ipv4.fib_has_custom_rules)
+		call_fib_notifier(nb, net, event_type, &info);
+#endif
+}
+
+static void fib_notify(struct net *net, struct notifier_block *nb,
+		       enum fib_event_type event_type);
+
+static int call_fib_entry_notifier(struct notifier_block *nb, struct net *net,
+				   enum fib_event_type event_type, u32 dst,
+				   int dst_len, struct fib_info *fi,
+				   u8 tos, u8 type, u32 tb_id, u32 nlflags)
+{
+	struct fib_entry_notifier_info info = {
+		.dst = dst,
+		.dst_len = dst_len,
+		.fi = fi,
+		.tos = tos,
+		.type = type,
+		.tb_id = tb_id,
+		.nlflags = nlflags,
+	};
+	return call_fib_notifier(nb, net, event_type, &info.info);
+}
+
+static bool fib_dump_is_consistent(struct notifier_block *nb,
+				   void (*cb)(struct notifier_block *nb),
+				   unsigned int fib_seq)
+{
+	atomic_notifier_chain_register(&fib_chain, nb);
+	if (fib_seq == fib_seq_sum())
+		return true;
+	atomic_notifier_chain_unregister(&fib_chain, nb);
+	if (cb)
+		cb(nb);
+	return false;
+}
+
+#define FIB_DUMP_MAX_RETRIES 5
+int register_fib_notifier(struct notifier_block *nb,
+			  void (*cb)(struct notifier_block *nb))
+{
+	int retries = 0;
+
+	do {
+		unsigned int fib_seq = fib_seq_sum();
+		struct net *net;
+
+		/* Mutex semantics guarantee that every change done to
+		 * FIB tries before we read the change sequence counter
+		 * is now visible to us.
+		 */
+		rcu_read_lock();
+		for_each_net_rcu(net) {
+			fib_rules_notify(net, nb, FIB_EVENT_RULE_ADD);
+			fib_notify(net, nb, FIB_EVENT_ENTRY_ADD);
+		}
+		rcu_read_unlock();
+
+		if (fib_dump_is_consistent(nb, cb, fib_seq))
+			return 0;
+	} while (++retries < FIB_DUMP_MAX_RETRIES);
+
+	return -EBUSY;
 }
 EXPORT_SYMBOL(register_fib_notifier);
 
@@ -1902,6 +1990,62 @@ int fib_table_flush(struct net *net, struct fib_table *tb)
 	return found;
 }
 
+static void fib_leaf_notify(struct net *net, struct key_vector *l,
+			    struct fib_table *tb, struct notifier_block *nb,
+			    enum fib_event_type event_type)
+{
+	struct fib_alias *fa;
+
+	hlist_for_each_entry_rcu(fa, &l->leaf, fa_list) {
+		struct fib_info *fi = fa->fa_info;
+
+		if (!fi)
+			continue;
+
+		/* local and main table can share the same trie,
+		 * so don't notify twice for the same entry.
+		 */
+		if (tb->tb_id != fa->tb_id)
+			continue;
+
+		call_fib_entry_notifier(nb, net, event_type, l->key,
+					KEYLENGTH - fa->fa_slen, fi, fa->fa_tos,
+					fa->fa_type, fa->tb_id, 0);
+	}
+}
+
+static void fib_table_notify(struct net *net, struct fib_table *tb,
+			     struct notifier_block *nb,
+			     enum fib_event_type event_type)
+{
+	struct trie *t = (struct trie *)tb->tb_data;
+	struct key_vector *l, *tp = t->kv;
+	t_key key = 0;
+
+	while ((l = leaf_walk_rcu(&tp, key)) != NULL) {
+		fib_leaf_notify(net, l, tb, nb, event_type);
+
+		key = l->key + 1;
+		/* stop in case of wrap around */
+		if (key < l->key)
+			break;
+	}
+}
+
+static void fib_notify(struct net *net, struct notifier_block *nb,
+		       enum fib_event_type event_type)
+{
+	unsigned int h;
+
+	for (h = 0; h < FIB_TABLE_HASHSZ; h++) {
+		struct hlist_head *head = &net->ipv4.fib_table_hash[h];
+		struct fib_table *tb;
+
+		hlist_for_each_entry_rcu(tb, head, tb_hlist)
+			fib_table_notify(net, tb, nb, event_type);
+	}
+}
+
 static void __trie_free_rcu(struct rcu_head *head)
 {
 	struct fib_table *tb = container_of(head, struct fib_table, rcu);
-- 
2.7.4

Re: [patch net-next v4 00/10] ipv4: fib: Replay events when registering FIB notifier

[David Miller]

From: Jiri Pirko <jiri@resnulli.us>
Date: Sat,  3 Dec 2016 16:44:57 +0100

> Ido says:
> 
> In kernel 4.9 the switchdev-specific FIB offload mechanism was replaced
> by a new FIB notification chain to which modules could register in order
> to be notified about the addition and deletion of FIB entries. The
> motivation for this change was that switchdev drivers need to be able to
> reflect the entire FIB table and not only FIBs configured on top of the
> port netdevs themselves. This is useful in case of in-band management.
> 
> The fundamental problem with this approach is that upon registration
> listeners lose all the information previously sent in the chain and
> thus have an incomplete view of the FIB tables, which can result in
> packet loss. This patchset fixes that by dumping the FIB tables and
> replaying notifications previously sent in the chain for the registered
> notification block.
> 
> The entire dump process is done under RCU and thus the FIB notification
> chain is converted to be atomic. The listeners are modified accordingly.
> This is done in the first eight patches.
> 
> The ninth patch adds a change sequence counter to ensure the integrity
> of the FIB dump. The last patch adds the dump itself to the FIB chain
> registration function and modifies existing listeners to pass a callback
> to be executed in case dump was inconsistent.
 ...

Series applied, thanks.