[PATCH net-next v4 00/13] net: xps: improve the xps maps handling

[PATCH net-next v4 00/13] net: xps: improve the xps maps handling

[Antoine Tenart]

Hello,

This series aims at fixing various issues with the xps code, including
out-of-bound accesses and use-after-free. While doing so we try to
improve the xps code maintainability and readability.

The main change is moving dev->num_tc and dev->nr_ids in the xps maps, to
avoid out-of-bound accesses as those two fields can be updated after the
maps have been allocated. This allows further reworks, to improve the
xps code readability and allow to stop taking the rtnl lock when
reading the maps in sysfs. The maps are moved to an array in net_device,
which simplifies the code a lot.

One future improvement may be to remove the use of xps_map_mutex from
net/core/dev.c, but that may require extra care.

Thanks!
Antoine

Since v3:
  - Removed the 3 patches about the rtnl lock and __netif_set_xps_queue
    as there are extra issues. Those patches were not tied to the
    others, and I'll see want can be done as a separate effort.
  - One small fix in patch 12.

Since v2:
  - Patches 13-16 are new to the series.
  - Fixed another issue I found while preparing v3 (use after free of
    old xps maps).
  - Kept the rtnl lock when calling netdev_get_tx_queue and
    netdev_txq_to_tc.
  - Use get_device/put_device when using the sb_dev.
  - Take the rtnl lock in mlx5 and virtio_net when calling
    netif_set_xps_queue.
  - Fixed a coding style issue.

Since v1:
  - Reordered the patches to improve readability and avoid introducing
    issues in between patches.
  - Use dev_maps->nr_ids to allocate the mask in xps_queue_show but
    still default to nr_cpu_ids/dev->num_rx_queues in xps_queue_show
    when dev_maps hasn't been allocated yet for backward
    compatibility.:w


Antoine Tenart (13):
  net-sysfs: convert xps_cpus_show to bitmap_zalloc
  net-sysfs: store the return of get_netdev_queue_index in an unsigned
    int
  net-sysfs: make xps_cpus_show and xps_rxqs_show consistent
  net: embed num_tc in the xps maps
  net: embed nr_ids in the xps maps
  net: remove the xps possible_mask
  net: move the xps maps to an array
  net: add an helper to copy xps maps to the new dev_maps
  net: improve queue removal readability in __netif_set_xps_queue
  net-sysfs: move the rtnl unlock up in the xps show helpers
  net-sysfs: move the xps cpus/rxqs retrieval in a common function
  net: fix use after free in xps
  net: NULL the old xps map entries when freeing them

 drivers/net/virtio_net.c  |   2 +-
 include/linux/netdevice.h |  27 ++++-
 net/core/dev.c            | 247 ++++++++++++++++++++------------------
 net/core/net-sysfs.c      | 177 +++++++++++----------------
 4 files changed, 222 insertions(+), 231 deletions(-)

-- 
2.30.2

[PATCH net-next v4 01/13] net-sysfs: convert xps_cpus_show to bitmap_zalloc

[Antoine Tenart]

Use bitmap_zalloc instead of zalloc_cpumask_var in xps_cpus_show to
align with xps_rxqs_show. This will improve maintenance and allow us to
factorize the two functions. The function should behave the same.

Signed-off-by: Antoine Tenart <atenart@kernel.org>
---
 net/core/net-sysfs.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 307628fdf380..3a083c0c9dd3 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -1367,8 +1367,7 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue,
 	int cpu, len, ret, num_tc = 1, tc = 0;
 	struct net_device *dev = queue->dev;
 	struct xps_dev_maps *dev_maps;
-	cpumask_var_t mask;
-	unsigned long index;
+	unsigned long *mask, index;
 
 	if (!netif_is_multiqueue(dev))
 		return -ENOENT;
@@ -1396,7 +1395,8 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue,
 		}
 	}
 
-	if (!zalloc_cpumask_var(&mask, GFP_KERNEL)) {
+	mask = bitmap_zalloc(nr_cpu_ids, GFP_KERNEL);
+	if (!mask) {
 		ret = -ENOMEM;
 		goto err_rtnl_unlock;
 	}
@@ -1414,7 +1414,7 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue,
 
 			for (i = map->len; i--;) {
 				if (map->queues[i] == index) {
-					cpumask_set_cpu(cpu, mask);
+					set_bit(cpu, mask);
 					break;
 				}
 			}
@@ -1424,8 +1424,8 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue,
 
 	rtnl_unlock();
 
-	len = snprintf(buf, PAGE_SIZE, "%*pb\n", cpumask_pr_args(mask));
-	free_cpumask_var(mask);
+	len = bitmap_print_to_pagebuf(false, buf, mask, nr_cpu_ids);
+	bitmap_free(mask);
 	return len < PAGE_SIZE ? len : -EINVAL;
 
 err_rtnl_unlock:
-- 
2.30.2

[PATCH net-next v4 02/13] net-sysfs: store the return of get_netdev_queue_index in an unsigned int

[Antoine Tenart]

In net-sysfs, get_netdev_queue_index returns an unsigned int. Some of
its callers use an unsigned long to store the returned value. Update the
code to be consistent, this should only be cosmetic.

Signed-off-by: Antoine Tenart <atenart@kernel.org>
---
 net/core/net-sysfs.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 3a083c0c9dd3..5dc4223f6b68 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -1367,7 +1367,8 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue,
 	int cpu, len, ret, num_tc = 1, tc = 0;
 	struct net_device *dev = queue->dev;
 	struct xps_dev_maps *dev_maps;
-	unsigned long *mask, index;
+	unsigned long *mask;
+	unsigned int index;
 
 	if (!netif_is_multiqueue(dev))
 		return -ENOENT;
@@ -1437,7 +1438,7 @@ static ssize_t xps_cpus_store(struct netdev_queue *queue,
 			      const char *buf, size_t len)
 {
 	struct net_device *dev = queue->dev;
-	unsigned long index;
+	unsigned int index;
 	cpumask_var_t mask;
 	int err;
 
@@ -1479,7 +1480,8 @@ static ssize_t xps_rxqs_show(struct netdev_queue *queue, char *buf)
 	int j, len, ret, num_tc = 1, tc = 0;
 	struct net_device *dev = queue->dev;
 	struct xps_dev_maps *dev_maps;
-	unsigned long *mask, index;
+	unsigned long *mask;
+	unsigned int index;
 
 	index = get_netdev_queue_index(queue);
 
@@ -1541,7 +1543,8 @@ static ssize_t xps_rxqs_store(struct netdev_queue *queue, const char *buf,
 {
 	struct net_device *dev = queue->dev;
 	struct net *net = dev_net(dev);
-	unsigned long *mask, index;
+	unsigned long *mask;
+	unsigned int index;
 	int err;
 
 	if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
-- 
2.30.2

[PATCH net-next v4 03/13] net-sysfs: make xps_cpus_show and xps_rxqs_show consistent

[Antoine Tenart]

Make the implementations of xps_cpus_show and xps_rxqs_show to converge,
as the two share the same logic but diverted over time. This should not
modify their behaviour but will help future changes and improve
maintenance.

Signed-off-by: Antoine Tenart <atenart@kernel.org>
---
 net/core/net-sysfs.c | 33 ++++++++++++++++++---------------
 1 file changed, 18 insertions(+), 15 deletions(-)

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 5dc4223f6b68..5f76183ad5bc 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -1364,7 +1364,7 @@ static const struct attribute_group dql_group = {
 static ssize_t xps_cpus_show(struct netdev_queue *queue,
 			     char *buf)
 {
-	int cpu, len, ret, num_tc = 1, tc = 0;
+	int j, len, ret, num_tc = 1, tc = 0;
 	struct net_device *dev = queue->dev;
 	struct xps_dev_maps *dev_maps;
 	unsigned long *mask;
@@ -1404,23 +1404,26 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue,
 
 	rcu_read_lock();
 	dev_maps = rcu_dereference(dev->xps_cpus_map);
-	if (dev_maps) {
-		for_each_possible_cpu(cpu) {
-			int i, tci = cpu * num_tc + tc;
-			struct xps_map *map;
-
-			map = rcu_dereference(dev_maps->attr_map[tci]);
-			if (!map)
-				continue;
-
-			for (i = map->len; i--;) {
-				if (map->queues[i] == index) {
-					set_bit(cpu, mask);
-					break;
-				}
+	if (!dev_maps)
+		goto out_no_maps;
+
+	for (j = -1; j = netif_attrmask_next(j, NULL, nr_cpu_ids),
+	     j < nr_cpu_ids;) {
+		int i, tci = j * num_tc + tc;
+		struct xps_map *map;
+
+		map = rcu_dereference(dev_maps->attr_map[tci]);
+		if (!map)
+			continue;
+
+		for (i = map->len; i--;) {
+			if (map->queues[i] == index) {
+				set_bit(j, mask);
+				break;
 			}
 		}
 	}
+out_no_maps:
 	rcu_read_unlock();
 
 	rtnl_unlock();
-- 
2.30.2

[PATCH net-next v4 04/13] net: embed num_tc in the xps maps

[Antoine Tenart]

The xps cpus/rxqs map is accessed using dev->num_tc, which is used when
allocating the map. But later updates of dev->num_tc can lead to having
a mismatch between the maps and how they're accessed. In such cases the
map values do not make any sense and out of bound accesses can occur
(that can be easily seen using KASAN).

This patch aims at fixing this by embedding num_tc into the maps, using
the value at the time the map is created. This brings two improvements:
- The maps can be accessed using the embedded num_tc, so we know for
  sure we won't have out of bound accesses.
- Checks can be made before accessing the maps so we know the values
  retrieved will make sense.

We also update __netif_set_xps_queue to conditionally copy old maps from
dev_maps in the new one only if the number of traffic classes from both
maps match.

Signed-off-by: Antoine Tenart <atenart@kernel.org>
---
 include/linux/netdevice.h |  6 ++++
 net/core/dev.c            | 63 +++++++++++++++++++++++++--------------
 net/core/net-sysfs.c      | 45 +++++++++++-----------------
 3 files changed, 64 insertions(+), 50 deletions(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 97254c089eb2..c38534c55ea1 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -771,9 +771,15 @@ struct xps_map {
 
 /*
  * This structure holds all XPS maps for device.  Maps are indexed by CPU.
+ *
+ * We keep track of the number of traffic classes used when the struct is
+ * allocated, in num_tc. This will be used to navigate the maps, to ensure we're
+ * not crossing its upper bound, as the original dev->num_tc can be updated in
+ * the meantime.
  */
 struct xps_dev_maps {
 	struct rcu_head rcu;
+	s16 num_tc;
 	struct xps_map __rcu *attr_map[]; /* Either CPUs map or RXQs map */
 };
 
diff --git a/net/core/dev.c b/net/core/dev.c
index 6bc20eabd2b0..4e29d1994fdd 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2491,7 +2491,7 @@ static bool remove_xps_queue_cpu(struct net_device *dev,
 				 struct xps_dev_maps *dev_maps,
 				 int cpu, u16 offset, u16 count)
 {
-	int num_tc = dev->num_tc ? : 1;
+	int num_tc = dev_maps->num_tc;
 	bool active = false;
 	int tci;
 
@@ -2634,10 +2634,10 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 {
 	const unsigned long *online_mask = NULL, *possible_mask = NULL;
 	struct xps_dev_maps *dev_maps, *new_dev_maps = NULL;
+	bool active = false, copy = false;
 	int i, j, tci, numa_node_id = -2;
 	int maps_sz, num_tc = 1, tc = 0;
 	struct xps_map *map, *new_map;
-	bool active = false;
 	unsigned int nr_ids;
 
 	if (dev->num_tc) {
@@ -2672,19 +2672,29 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 	if (maps_sz < L1_CACHE_BYTES)
 		maps_sz = L1_CACHE_BYTES;
 
+	/* The old dev_maps could be larger or smaller than the one we're
+	 * setting up now, as dev->num_tc could have been updated in between. We
+	 * could try to be smart, but let's be safe instead and only copy
+	 * foreign traffic classes if the two map sizes match.
+	 */
+	if (dev_maps && dev_maps->num_tc == num_tc)
+		copy = true;
+
 	/* allocate memory for queue storage */
 	for (j = -1; j = netif_attrmask_next_and(j, online_mask, mask, nr_ids),
 	     j < nr_ids;) {
-		if (!new_dev_maps)
-			new_dev_maps = kzalloc(maps_sz, GFP_KERNEL);
 		if (!new_dev_maps) {
-			mutex_unlock(&xps_map_mutex);
-			return -ENOMEM;
+			new_dev_maps = kzalloc(maps_sz, GFP_KERNEL);
+			if (!new_dev_maps) {
+				mutex_unlock(&xps_map_mutex);
+				return -ENOMEM;
+			}
+
+			new_dev_maps->num_tc = num_tc;
 		}
 
 		tci = j * num_tc + tc;
-		map = dev_maps ? xmap_dereference(dev_maps->attr_map[tci]) :
-				 NULL;
+		map = copy ? xmap_dereference(dev_maps->attr_map[tci]) : NULL;
 
 		map = expand_xps_map(map, j, index, is_rxqs_map);
 		if (!map)
@@ -2706,7 +2716,7 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 	for (j = -1; j = netif_attrmask_next(j, possible_mask, nr_ids),
 	     j < nr_ids;) {
 		/* copy maps belonging to foreign traffic classes */
-		for (i = tc, tci = j * num_tc; dev_maps && i--; tci++) {
+		for (i = tc, tci = j * num_tc; copy && i--; tci++) {
 			/* fill in the new device map from the old device map */
 			map = xmap_dereference(dev_maps->attr_map[tci]);
 			RCU_INIT_POINTER(new_dev_maps->attr_map[tci], map);
@@ -2736,14 +2746,14 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 					numa_node_id = -1;
 			}
 #endif
-		} else if (dev_maps) {
+		} else if (copy) {
 			/* fill in the new device map from the old device map */
 			map = xmap_dereference(dev_maps->attr_map[tci]);
 			RCU_INIT_POINTER(new_dev_maps->attr_map[tci], map);
 		}
 
 		/* copy maps belonging to foreign traffic classes */
-		for (i = num_tc - tc, tci++; dev_maps && --i; tci++) {
+		for (i = num_tc - tc, tci++; copy && --i; tci++) {
 			/* fill in the new device map from the old device map */
 			map = xmap_dereference(dev_maps->attr_map[tci]);
 			RCU_INIT_POINTER(new_dev_maps->attr_map[tci], map);
@@ -2761,11 +2771,18 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 
 	for (j = -1; j = netif_attrmask_next(j, possible_mask, nr_ids),
 	     j < nr_ids;) {
-		for (i = num_tc, tci = j * num_tc; i--; tci++) {
-			new_map = xmap_dereference(new_dev_maps->attr_map[tci]);
+		for (i = num_tc, tci = j * dev_maps->num_tc; i--; tci++) {
 			map = xmap_dereference(dev_maps->attr_map[tci]);
-			if (map && map != new_map)
-				kfree_rcu(map, rcu);
+			if (!map)
+				continue;
+
+			if (copy) {
+				new_map = xmap_dereference(new_dev_maps->attr_map[tci]);
+				if (map == new_map)
+					continue;
+			}
+
+			kfree_rcu(map, rcu);
 		}
 	}
 
@@ -2789,12 +2806,12 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 	/* removes tx-queue from unused CPUs/rx-queues */
 	for (j = -1; j = netif_attrmask_next(j, possible_mask, nr_ids),
 	     j < nr_ids;) {
-		for (i = tc, tci = j * num_tc; i--; tci++)
+		for (i = tc, tci = j * dev_maps->num_tc; i--; tci++)
 			active |= remove_xps_queue(dev_maps, tci, index);
 		if (!netif_attr_test_mask(j, mask, nr_ids) ||
 		    !netif_attr_test_online(j, online_mask, nr_ids))
 			active |= remove_xps_queue(dev_maps, tci, index);
-		for (i = num_tc - tc, tci++; --i; tci++)
+		for (i = dev_maps->num_tc - tc, tci++; --i; tci++)
 			active |= remove_xps_queue(dev_maps, tci, index);
 	}
 
@@ -2812,7 +2829,7 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 	     j < nr_ids;) {
 		for (i = num_tc, tci = j * num_tc; i--; tci++) {
 			new_map = xmap_dereference(new_dev_maps->attr_map[tci]);
-			map = dev_maps ?
+			map = copy ?
 			      xmap_dereference(dev_maps->attr_map[tci]) :
 			      NULL;
 			if (new_map && new_map != map)
@@ -3944,13 +3961,15 @@ sch_handle_egress(struct sk_buff *skb, int *ret, struct net_device *dev)
 static int __get_xps_queue_idx(struct net_device *dev, struct sk_buff *skb,
 			       struct xps_dev_maps *dev_maps, unsigned int tci)
 {
+	int tc = netdev_get_prio_tc_map(dev, skb->priority);
 	struct xps_map *map;
 	int queue_index = -1;
 
-	if (dev->num_tc) {
-		tci *= dev->num_tc;
-		tci += netdev_get_prio_tc_map(dev, skb->priority);
-	}
+	if (tc >= dev_maps->num_tc)
+		return queue_index;
+
+	tci *= dev_maps->num_tc;
+	tci += tc;
 
 	map = rcu_dereference(dev_maps->attr_map[tci]);
 	if (map) {
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 5f76183ad5bc..1364d0f39cb0 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -1364,9 +1364,9 @@ static const struct attribute_group dql_group = {
 static ssize_t xps_cpus_show(struct netdev_queue *queue,
 			     char *buf)
 {
-	int j, len, ret, num_tc = 1, tc = 0;
 	struct net_device *dev = queue->dev;
 	struct xps_dev_maps *dev_maps;
+	int j, len, ret, tc = 0;
 	unsigned long *mask;
 	unsigned int index;
 
@@ -1378,22 +1378,13 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue,
 	if (!rtnl_trylock())
 		return restart_syscall();
 
-	if (dev->num_tc) {
-		/* Do not allow XPS on subordinate device directly */
-		num_tc = dev->num_tc;
-		if (num_tc < 0) {
-			ret = -EINVAL;
-			goto err_rtnl_unlock;
-		}
-
-		/* If queue belongs to subordinate dev use its map */
-		dev = netdev_get_tx_queue(dev, index)->sb_dev ? : dev;
+	/* If queue belongs to subordinate dev use its map */
+	dev = netdev_get_tx_queue(dev, index)->sb_dev ? : dev;
 
-		tc = netdev_txq_to_tc(dev, index);
-		if (tc < 0) {
-			ret = -EINVAL;
-			goto err_rtnl_unlock;
-		}
+	tc = netdev_txq_to_tc(dev, index);
+	if (tc < 0) {
+		ret = -EINVAL;
+		goto err_rtnl_unlock;
 	}
 
 	mask = bitmap_zalloc(nr_cpu_ids, GFP_KERNEL);
@@ -1404,12 +1395,12 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue,
 
 	rcu_read_lock();
 	dev_maps = rcu_dereference(dev->xps_cpus_map);
-	if (!dev_maps)
+	if (!dev_maps || tc >= dev_maps->num_tc)
 		goto out_no_maps;
 
 	for (j = -1; j = netif_attrmask_next(j, NULL, nr_cpu_ids),
 	     j < nr_cpu_ids;) {
-		int i, tci = j * num_tc + tc;
+		int i, tci = j * dev_maps->num_tc + tc;
 		struct xps_map *map;
 
 		map = rcu_dereference(dev_maps->attr_map[tci]);
@@ -1480,9 +1471,9 @@ static struct netdev_queue_attribute xps_cpus_attribute __ro_after_init
 
 static ssize_t xps_rxqs_show(struct netdev_queue *queue, char *buf)
 {
-	int j, len, ret, num_tc = 1, tc = 0;
 	struct net_device *dev = queue->dev;
 	struct xps_dev_maps *dev_maps;
+	int j, len, ret, tc = 0;
 	unsigned long *mask;
 	unsigned int index;
 
@@ -1491,14 +1482,12 @@ static ssize_t xps_rxqs_show(struct netdev_queue *queue, char *buf)
 	if (!rtnl_trylock())
 		return restart_syscall();
 
-	if (dev->num_tc) {
-		num_tc = dev->num_tc;
-		tc = netdev_txq_to_tc(dev, index);
-		if (tc < 0) {
-			ret = -EINVAL;
-			goto err_rtnl_unlock;
-		}
+	tc = netdev_txq_to_tc(dev, index);
+	if (tc < 0) {
+		ret = -EINVAL;
+		goto err_rtnl_unlock;
 	}
+
 	mask = bitmap_zalloc(dev->num_rx_queues, GFP_KERNEL);
 	if (!mask) {
 		ret = -ENOMEM;
@@ -1507,12 +1496,12 @@ static ssize_t xps_rxqs_show(struct netdev_queue *queue, char *buf)
 
 	rcu_read_lock();
 	dev_maps = rcu_dereference(dev->xps_rxqs_map);
-	if (!dev_maps)
+	if (!dev_maps || tc >= dev_maps->num_tc)
 		goto out_no_maps;
 
 	for (j = -1; j = netif_attrmask_next(j, NULL, dev->num_rx_queues),
 	     j < dev->num_rx_queues;) {
-		int i, tci = j * num_tc + tc;
+		int i, tci = j * dev_maps->num_tc + tc;
 		struct xps_map *map;
 
 		map = rcu_dereference(dev_maps->attr_map[tci]);
-- 
2.30.2

[PATCH net-next v4 05/13] net: embed nr_ids in the xps maps

[Antoine Tenart]

Embed nr_ids (the number of cpu for the xps cpus map, and the number of
rxqs for the xps cpus map) in dev_maps. That will help not accessing out
of bound memory if those values change after dev_maps was allocated.

Suggested-by: Alexander Duyck <alexander.duyck@gmail.com>
Signed-off-by: Antoine Tenart <atenart@kernel.org>
---
 include/linux/netdevice.h |  4 ++++
 net/core/dev.c            | 45 ++++++++++++++++++---------------------
 net/core/net-sysfs.c      | 38 +++++++++++++++++++--------------
 3 files changed, 47 insertions(+), 40 deletions(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index c38534c55ea1..09e73f5a8c78 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -772,6 +772,9 @@ struct xps_map {
 /*
  * This structure holds all XPS maps for device.  Maps are indexed by CPU.
  *
+ * We keep track of the number of cpus/rxqs used when the struct is allocated,
+ * in nr_ids. This will help not accessing out-of-bound memory.
+ *
  * We keep track of the number of traffic classes used when the struct is
  * allocated, in num_tc. This will be used to navigate the maps, to ensure we're
  * not crossing its upper bound, as the original dev->num_tc can be updated in
@@ -779,6 +782,7 @@ struct xps_map {
  */
 struct xps_dev_maps {
 	struct rcu_head rcu;
+	unsigned int nr_ids;
 	s16 num_tc;
 	struct xps_map __rcu *attr_map[]; /* Either CPUs map or RXQs map */
 };
diff --git a/net/core/dev.c b/net/core/dev.c
index 4e29d1994fdd..7530c95970a0 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2524,14 +2524,14 @@ static void reset_xps_maps(struct net_device *dev,
 }
 
 static void clean_xps_maps(struct net_device *dev, const unsigned long *mask,
-			   struct xps_dev_maps *dev_maps, unsigned int nr_ids,
-			   u16 offset, u16 count, bool is_rxqs_map)
+			   struct xps_dev_maps *dev_maps, u16 offset, u16 count,
+			   bool is_rxqs_map)
 {
+	unsigned int nr_ids = dev_maps->nr_ids;
 	bool active = false;
 	int i, j;
 
-	for (j = -1; j = netif_attrmask_next(j, mask, nr_ids),
-	     j < nr_ids;)
+	for (j = -1; j = netif_attrmask_next(j, mask, nr_ids), j < nr_ids;)
 		active |= remove_xps_queue_cpu(dev, dev_maps, j, offset,
 					       count);
 	if (!active)
@@ -2551,7 +2551,6 @@ static void netif_reset_xps_queues(struct net_device *dev, u16 offset,
 {
 	const unsigned long *possible_mask = NULL;
 	struct xps_dev_maps *dev_maps;
-	unsigned int nr_ids;
 
 	if (!static_key_false(&xps_needed))
 		return;
@@ -2561,11 +2560,9 @@ static void netif_reset_xps_queues(struct net_device *dev, u16 offset,
 
 	if (static_key_false(&xps_rxqs_needed)) {
 		dev_maps = xmap_dereference(dev->xps_rxqs_map);
-		if (dev_maps) {
-			nr_ids = dev->num_rx_queues;
-			clean_xps_maps(dev, possible_mask, dev_maps, nr_ids,
-				       offset, count, true);
-		}
+		if (dev_maps)
+			clean_xps_maps(dev, possible_mask, dev_maps, offset,
+				       count, true);
 	}
 
 	dev_maps = xmap_dereference(dev->xps_cpus_map);
@@ -2574,9 +2571,7 @@ static void netif_reset_xps_queues(struct net_device *dev, u16 offset,
 
 	if (num_possible_cpus() > 1)
 		possible_mask = cpumask_bits(cpu_possible_mask);
-	nr_ids = nr_cpu_ids;
-	clean_xps_maps(dev, possible_mask, dev_maps, nr_ids, offset, count,
-		       false);
+	clean_xps_maps(dev, possible_mask, dev_maps, offset, count, false);
 
 out_no_maps:
 	mutex_unlock(&xps_map_mutex);
@@ -2673,11 +2668,12 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 		maps_sz = L1_CACHE_BYTES;
 
 	/* The old dev_maps could be larger or smaller than the one we're
-	 * setting up now, as dev->num_tc could have been updated in between. We
-	 * could try to be smart, but let's be safe instead and only copy
-	 * foreign traffic classes if the two map sizes match.
+	 * setting up now, as dev->num_tc or nr_ids could have been updated in
+	 * between. We could try to be smart, but let's be safe instead and only
+	 * copy foreign traffic classes if the two map sizes match.
 	 */
-	if (dev_maps && dev_maps->num_tc == num_tc)
+	if (dev_maps &&
+	    dev_maps->num_tc == num_tc && dev_maps->nr_ids == nr_ids)
 		copy = true;
 
 	/* allocate memory for queue storage */
@@ -2690,6 +2686,7 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 				return -ENOMEM;
 			}
 
+			new_dev_maps->nr_ids = nr_ids;
 			new_dev_maps->num_tc = num_tc;
 		}
 
@@ -2770,7 +2767,7 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 		goto out_no_old_maps;
 
 	for (j = -1; j = netif_attrmask_next(j, possible_mask, nr_ids),
-	     j < nr_ids;) {
+	     j < dev_maps->nr_ids;) {
 		for (i = num_tc, tci = j * dev_maps->num_tc; i--; tci++) {
 			map = xmap_dereference(dev_maps->attr_map[tci]);
 			if (!map)
@@ -2804,12 +2801,12 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 		goto out_no_maps;
 
 	/* removes tx-queue from unused CPUs/rx-queues */
-	for (j = -1; j = netif_attrmask_next(j, possible_mask, nr_ids),
-	     j < nr_ids;) {
+	for (j = -1; j = netif_attrmask_next(j, possible_mask, dev_maps->nr_ids),
+	     j < dev_maps->nr_ids;) {
 		for (i = tc, tci = j * dev_maps->num_tc; i--; tci++)
 			active |= remove_xps_queue(dev_maps, tci, index);
-		if (!netif_attr_test_mask(j, mask, nr_ids) ||
-		    !netif_attr_test_online(j, online_mask, nr_ids))
+		if (!netif_attr_test_mask(j, mask, dev_maps->nr_ids) ||
+		    !netif_attr_test_online(j, online_mask, dev_maps->nr_ids))
 			active |= remove_xps_queue(dev_maps, tci, index);
 		for (i = dev_maps->num_tc - tc, tci++; --i; tci++)
 			active |= remove_xps_queue(dev_maps, tci, index);
@@ -3965,7 +3962,7 @@ static int __get_xps_queue_idx(struct net_device *dev, struct sk_buff *skb,
 	struct xps_map *map;
 	int queue_index = -1;
 
-	if (tc >= dev_maps->num_tc)
+	if (tc >= dev_maps->num_tc || tci >= dev_maps->nr_ids)
 		return queue_index;
 
 	tci *= dev_maps->num_tc;
@@ -4004,7 +4001,7 @@ static int get_xps_queue(struct net_device *dev, struct net_device *sb_dev,
 	if (dev_maps) {
 		int tci = sk_rx_queue_get(sk);
 
-		if (tci >= 0 && tci < dev->num_rx_queues)
+		if (tci >= 0)
 			queue_index = __get_xps_queue_idx(dev, skb, dev_maps,
 							  tci);
 	}
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 1364d0f39cb0..bb08bdc88fa9 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -1366,9 +1366,9 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue,
 {
 	struct net_device *dev = queue->dev;
 	struct xps_dev_maps *dev_maps;
+	unsigned int index, nr_ids;
 	int j, len, ret, tc = 0;
 	unsigned long *mask;
-	unsigned int index;
 
 	if (!netif_is_multiqueue(dev))
 		return -ENOENT;
@@ -1387,19 +1387,20 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue,
 		goto err_rtnl_unlock;
 	}
 
-	mask = bitmap_zalloc(nr_cpu_ids, GFP_KERNEL);
+	rcu_read_lock();
+	dev_maps = rcu_dereference(dev->xps_cpus_map);
+	nr_ids = dev_maps ? dev_maps->nr_ids : nr_cpu_ids;
+
+	mask = bitmap_zalloc(nr_ids, GFP_KERNEL);
 	if (!mask) {
 		ret = -ENOMEM;
-		goto err_rtnl_unlock;
+		goto err_rcu_unlock;
 	}
 
-	rcu_read_lock();
-	dev_maps = rcu_dereference(dev->xps_cpus_map);
 	if (!dev_maps || tc >= dev_maps->num_tc)
 		goto out_no_maps;
 
-	for (j = -1; j = netif_attrmask_next(j, NULL, nr_cpu_ids),
-	     j < nr_cpu_ids;) {
+	for (j = -1; j = netif_attrmask_next(j, NULL, nr_ids), j < nr_ids;) {
 		int i, tci = j * dev_maps->num_tc + tc;
 		struct xps_map *map;
 
@@ -1419,10 +1420,12 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue,
 
 	rtnl_unlock();
 
-	len = bitmap_print_to_pagebuf(false, buf, mask, nr_cpu_ids);
+	len = bitmap_print_to_pagebuf(false, buf, mask, nr_ids);
 	bitmap_free(mask);
 	return len < PAGE_SIZE ? len : -EINVAL;
 
+err_rcu_unlock:
+	rcu_read_unlock();
 err_rtnl_unlock:
 	rtnl_unlock();
 	return ret;
@@ -1473,9 +1476,9 @@ static ssize_t xps_rxqs_show(struct netdev_queue *queue, char *buf)
 {
 	struct net_device *dev = queue->dev;
 	struct xps_dev_maps *dev_maps;
+	unsigned int index, nr_ids;
 	int j, len, ret, tc = 0;
 	unsigned long *mask;
-	unsigned int index;
 
 	index = get_netdev_queue_index(queue);
 
@@ -1488,19 +1491,20 @@ static ssize_t xps_rxqs_show(struct netdev_queue *queue, char *buf)
 		goto err_rtnl_unlock;
 	}
 
-	mask = bitmap_zalloc(dev->num_rx_queues, GFP_KERNEL);
+	rcu_read_lock();
+	dev_maps = rcu_dereference(dev->xps_rxqs_map);
+	nr_ids = dev_maps ? dev_maps->nr_ids : dev->num_rx_queues;
+
+	mask = bitmap_zalloc(nr_ids, GFP_KERNEL);
 	if (!mask) {
 		ret = -ENOMEM;
-		goto err_rtnl_unlock;
+		goto err_rcu_unlock;
 	}
 
-	rcu_read_lock();
-	dev_maps = rcu_dereference(dev->xps_rxqs_map);
 	if (!dev_maps || tc >= dev_maps->num_tc)
 		goto out_no_maps;
 
-	for (j = -1; j = netif_attrmask_next(j, NULL, dev->num_rx_queues),
-	     j < dev->num_rx_queues;) {
+	for (j = -1; j = netif_attrmask_next(j, NULL, nr_ids), j < nr_ids;) {
 		int i, tci = j * dev_maps->num_tc + tc;
 		struct xps_map *map;
 
@@ -1520,11 +1524,13 @@ static ssize_t xps_rxqs_show(struct netdev_queue *queue, char *buf)
 
 	rtnl_unlock();
 
-	len = bitmap_print_to_pagebuf(false, buf, mask, dev->num_rx_queues);
+	len = bitmap_print_to_pagebuf(false, buf, mask, nr_ids);
 	bitmap_free(mask);
 
 	return len < PAGE_SIZE ? len : -EINVAL;
 
+err_rcu_unlock:
+	rcu_read_unlock();
 err_rtnl_unlock:
 	rtnl_unlock();
 	return ret;
-- 
2.30.2

[PATCH net-next v4 06/13] net: remove the xps possible_mask

[Antoine Tenart]

Remove the xps possible_mask. It was an optimization but we can just
loop from 0 to nr_ids now that it is embedded in the xps dev_maps. That
simplifies the code a bit.

Suggested-by: Alexander Duyck <alexander.duyck@gmail.com>
Signed-off-by: Antoine Tenart <atenart@kernel.org>
---
 net/core/dev.c       | 40 +++++++++++++---------------------------
 net/core/net-sysfs.c |  4 ++--
 2 files changed, 15 insertions(+), 29 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index 7530c95970a0..3ed8cb3a4061 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2523,33 +2523,28 @@ static void reset_xps_maps(struct net_device *dev,
 	kfree_rcu(dev_maps, rcu);
 }
 
-static void clean_xps_maps(struct net_device *dev, const unsigned long *mask,
+static void clean_xps_maps(struct net_device *dev,
 			   struct xps_dev_maps *dev_maps, u16 offset, u16 count,
 			   bool is_rxqs_map)
 {
-	unsigned int nr_ids = dev_maps->nr_ids;
 	bool active = false;
 	int i, j;
 
-	for (j = -1; j = netif_attrmask_next(j, mask, nr_ids), j < nr_ids;)
-		active |= remove_xps_queue_cpu(dev, dev_maps, j, offset,
-					       count);
+	for (j = 0; j < dev_maps->nr_ids; j++)
+		active |= remove_xps_queue_cpu(dev, dev_maps, j, offset, count);
 	if (!active)
 		reset_xps_maps(dev, dev_maps, is_rxqs_map);
 
 	if (!is_rxqs_map) {
-		for (i = offset + (count - 1); count--; i--) {
+		for (i = offset + (count - 1); count--; i--)
 			netdev_queue_numa_node_write(
-				netdev_get_tx_queue(dev, i),
-				NUMA_NO_NODE);
-		}
+				netdev_get_tx_queue(dev, i), NUMA_NO_NODE);
 	}
 }
 
 static void netif_reset_xps_queues(struct net_device *dev, u16 offset,
 				   u16 count)
 {
-	const unsigned long *possible_mask = NULL;
 	struct xps_dev_maps *dev_maps;
 
 	if (!static_key_false(&xps_needed))
@@ -2561,17 +2556,14 @@ static void netif_reset_xps_queues(struct net_device *dev, u16 offset,
 	if (static_key_false(&xps_rxqs_needed)) {
 		dev_maps = xmap_dereference(dev->xps_rxqs_map);
 		if (dev_maps)
-			clean_xps_maps(dev, possible_mask, dev_maps, offset,
-				       count, true);
+			clean_xps_maps(dev, dev_maps, offset, count, true);
 	}
 
 	dev_maps = xmap_dereference(dev->xps_cpus_map);
 	if (!dev_maps)
 		goto out_no_maps;
 
-	if (num_possible_cpus() > 1)
-		possible_mask = cpumask_bits(cpu_possible_mask);
-	clean_xps_maps(dev, possible_mask, dev_maps, offset, count, false);
+	clean_xps_maps(dev, dev_maps, offset, count, false);
 
 out_no_maps:
 	mutex_unlock(&xps_map_mutex);
@@ -2627,8 +2619,8 @@ static struct xps_map *expand_xps_map(struct xps_map *map, int attr_index,
 int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 			  u16 index, bool is_rxqs_map)
 {
-	const unsigned long *online_mask = NULL, *possible_mask = NULL;
 	struct xps_dev_maps *dev_maps, *new_dev_maps = NULL;
+	const unsigned long *online_mask = NULL;
 	bool active = false, copy = false;
 	int i, j, tci, numa_node_id = -2;
 	int maps_sz, num_tc = 1, tc = 0;
@@ -2656,10 +2648,8 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 		nr_ids = dev->num_rx_queues;
 	} else {
 		maps_sz = XPS_CPU_DEV_MAPS_SIZE(num_tc);
-		if (num_possible_cpus() > 1) {
+		if (num_possible_cpus() > 1)
 			online_mask = cpumask_bits(cpu_online_mask);
-			possible_mask = cpumask_bits(cpu_possible_mask);
-		}
 		dev_maps = xmap_dereference(dev->xps_cpus_map);
 		nr_ids = nr_cpu_ids;
 	}
@@ -2710,8 +2700,7 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 			static_key_slow_inc_cpuslocked(&xps_rxqs_needed);
 	}
 
-	for (j = -1; j = netif_attrmask_next(j, possible_mask, nr_ids),
-	     j < nr_ids;) {
+	for (j = 0; j < nr_ids; j++) {
 		/* copy maps belonging to foreign traffic classes */
 		for (i = tc, tci = j * num_tc; copy && i--; tci++) {
 			/* fill in the new device map from the old device map */
@@ -2766,8 +2755,7 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 	if (!dev_maps)
 		goto out_no_old_maps;
 
-	for (j = -1; j = netif_attrmask_next(j, possible_mask, nr_ids),
-	     j < dev_maps->nr_ids;) {
+	for (j = 0; j < dev_maps->nr_ids; j++) {
 		for (i = num_tc, tci = j * dev_maps->num_tc; i--; tci++) {
 			map = xmap_dereference(dev_maps->attr_map[tci]);
 			if (!map)
@@ -2801,8 +2789,7 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 		goto out_no_maps;
 
 	/* removes tx-queue from unused CPUs/rx-queues */
-	for (j = -1; j = netif_attrmask_next(j, possible_mask, dev_maps->nr_ids),
-	     j < dev_maps->nr_ids;) {
+	for (j = 0; j < dev_maps->nr_ids; j++) {
 		for (i = tc, tci = j * dev_maps->num_tc; i--; tci++)
 			active |= remove_xps_queue(dev_maps, tci, index);
 		if (!netif_attr_test_mask(j, mask, dev_maps->nr_ids) ||
@@ -2822,8 +2809,7 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 	return 0;
 error:
 	/* remove any maps that we added */
-	for (j = -1; j = netif_attrmask_next(j, possible_mask, nr_ids),
-	     j < nr_ids;) {
+	for (j = 0; j < nr_ids; j++) {
 		for (i = num_tc, tci = j * num_tc; i--; tci++) {
 			new_map = xmap_dereference(new_dev_maps->attr_map[tci]);
 			map = copy ?
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index bb08bdc88fa9..c762c435ff76 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -1400,7 +1400,7 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue,
 	if (!dev_maps || tc >= dev_maps->num_tc)
 		goto out_no_maps;
 
-	for (j = -1; j = netif_attrmask_next(j, NULL, nr_ids), j < nr_ids;) {
+	for (j = 0; j < nr_ids; j++) {
 		int i, tci = j * dev_maps->num_tc + tc;
 		struct xps_map *map;
 
@@ -1504,7 +1504,7 @@ static ssize_t xps_rxqs_show(struct netdev_queue *queue, char *buf)
 	if (!dev_maps || tc >= dev_maps->num_tc)
 		goto out_no_maps;
 
-	for (j = -1; j = netif_attrmask_next(j, NULL, nr_ids), j < nr_ids;) {
+	for (j = 0; j < nr_ids; j++) {
 		int i, tci = j * dev_maps->num_tc + tc;
 		struct xps_map *map;
 
-- 
2.30.2

[PATCH net-next v4 07/13] net: move the xps maps to an array

[Antoine Tenart]

Move the xps maps (xps_cpus_map and xps_rxqs_map) to an array in
net_device. That will simplify a lot the code removing the need for lots
of if/else conditionals as the correct map will be available using its
offset in the array.

This should not modify the xps maps behaviour in any way.

Suggested-by: Alexander Duyck <alexander.duyck@gmail.com>
Signed-off-by: Antoine Tenart <atenart@kernel.org>
---
 drivers/net/virtio_net.c  |  2 +-
 include/linux/netdevice.h | 17 +++++----
 net/core/dev.c            | 73 +++++++++++++++++----------------------
 net/core/net-sysfs.c      |  6 ++--
 4 files changed, 46 insertions(+), 52 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 77ba8e2fc11c..584a9bd59dda 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -2015,7 +2015,7 @@ static void virtnet_set_affinity(struct virtnet_info *vi)
 		}
 		virtqueue_set_affinity(vi->rq[i].vq, mask);
 		virtqueue_set_affinity(vi->sq[i].vq, mask);
-		__netif_set_xps_queue(vi->dev, cpumask_bits(mask), i, false);
+		__netif_set_xps_queue(vi->dev, cpumask_bits(mask), i, XPS_CPUS);
 		cpumask_clear(mask);
 	}
 
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 09e73f5a8c78..4940509999be 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -754,6 +754,13 @@ struct rx_queue_attribute {
 			 const char *buf, size_t len);
 };
 
+/* XPS map type and offset of the xps map within net_device->xps_maps[]. */
+enum xps_map_type {
+	XPS_CPUS = 0,
+	XPS_RXQS,
+	XPS_MAPS_MAX,
+};
+
 #ifdef CONFIG_XPS
 /*
  * This structure holds an XPS map which can be of variable length.  The
@@ -1773,8 +1780,7 @@ enum netdev_ml_priv_type {
  *	@tx_queue_len:		Max frames per queue allowed
  *	@tx_global_lock: 	XXX: need comments on this one
  *	@xdp_bulkq:		XDP device bulk queue
- *	@xps_cpus_map:		all CPUs map for XPS device
- *	@xps_rxqs_map:		all RXQs map for XPS device
+ *	@xps_maps:		all CPUs/RXQs maps for XPS device
  *
  *	@xps_maps:	XXX: need comments on this one
  *	@miniq_egress:		clsact qdisc specific data for
@@ -2070,8 +2076,7 @@ struct net_device {
 	struct xdp_dev_bulk_queue __percpu *xdp_bulkq;
 
 #ifdef CONFIG_XPS
-	struct xps_dev_maps __rcu *xps_cpus_map;
-	struct xps_dev_maps __rcu *xps_rxqs_map;
+	struct xps_dev_maps __rcu *xps_maps[XPS_MAPS_MAX];
 #endif
 #ifdef CONFIG_NET_CLS_ACT
 	struct mini_Qdisc __rcu	*miniq_egress;
@@ -3701,7 +3706,7 @@ static inline void netif_wake_subqueue(struct net_device *dev, u16 queue_index)
 int netif_set_xps_queue(struct net_device *dev, const struct cpumask *mask,
 			u16 index);
 int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
-			  u16 index, bool is_rxqs_map);
+			  u16 index, enum xps_map_type type);
 
 /**
  *	netif_attr_test_mask - Test a CPU or Rx queue set in a mask
@@ -3796,7 +3801,7 @@ static inline int netif_set_xps_queue(struct net_device *dev,
 
 static inline int __netif_set_xps_queue(struct net_device *dev,
 					const unsigned long *mask,
-					u16 index, bool is_rxqs_map)
+					u16 index, enum xps_map_type type)
 {
 	return 0;
 }
diff --git a/net/core/dev.c b/net/core/dev.c
index 3ed8cb3a4061..af57e32bb543 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2511,31 +2511,34 @@ static bool remove_xps_queue_cpu(struct net_device *dev,
 
 static void reset_xps_maps(struct net_device *dev,
 			   struct xps_dev_maps *dev_maps,
-			   bool is_rxqs_map)
+			   enum xps_map_type type)
 {
-	if (is_rxqs_map) {
-		static_key_slow_dec_cpuslocked(&xps_rxqs_needed);
-		RCU_INIT_POINTER(dev->xps_rxqs_map, NULL);
-	} else {
-		RCU_INIT_POINTER(dev->xps_cpus_map, NULL);
-	}
 	static_key_slow_dec_cpuslocked(&xps_needed);
+	if (type == XPS_RXQS)
+		static_key_slow_dec_cpuslocked(&xps_rxqs_needed);
+
+	RCU_INIT_POINTER(dev->xps_maps[type], NULL);
+
 	kfree_rcu(dev_maps, rcu);
 }
 
-static void clean_xps_maps(struct net_device *dev,
-			   struct xps_dev_maps *dev_maps, u16 offset, u16 count,
-			   bool is_rxqs_map)
+static void clean_xps_maps(struct net_device *dev, enum xps_map_type type,
+			   u16 offset, u16 count)
 {
+	struct xps_dev_maps *dev_maps;
 	bool active = false;
 	int i, j;
 
+	dev_maps = xmap_dereference(dev->xps_maps[type]);
+	if (!dev_maps)
+		return;
+
 	for (j = 0; j < dev_maps->nr_ids; j++)
 		active |= remove_xps_queue_cpu(dev, dev_maps, j, offset, count);
 	if (!active)
-		reset_xps_maps(dev, dev_maps, is_rxqs_map);
+		reset_xps_maps(dev, dev_maps, type);
 
-	if (!is_rxqs_map) {
+	if (type == XPS_CPUS) {
 		for (i = offset + (count - 1); count--; i--)
 			netdev_queue_numa_node_write(
 				netdev_get_tx_queue(dev, i), NUMA_NO_NODE);
@@ -2545,27 +2548,17 @@ static void clean_xps_maps(struct net_device *dev,
 static void netif_reset_xps_queues(struct net_device *dev, u16 offset,
 				   u16 count)
 {
-	struct xps_dev_maps *dev_maps;
-
 	if (!static_key_false(&xps_needed))
 		return;
 
 	cpus_read_lock();
 	mutex_lock(&xps_map_mutex);
 
-	if (static_key_false(&xps_rxqs_needed)) {
-		dev_maps = xmap_dereference(dev->xps_rxqs_map);
-		if (dev_maps)
-			clean_xps_maps(dev, dev_maps, offset, count, true);
-	}
-
-	dev_maps = xmap_dereference(dev->xps_cpus_map);
-	if (!dev_maps)
-		goto out_no_maps;
+	if (static_key_false(&xps_rxqs_needed))
+		clean_xps_maps(dev, XPS_RXQS, offset, count);
 
-	clean_xps_maps(dev, dev_maps, offset, count, false);
+	clean_xps_maps(dev, XPS_CPUS, offset, count);
 
-out_no_maps:
 	mutex_unlock(&xps_map_mutex);
 	cpus_read_unlock();
 }
@@ -2617,7 +2610,7 @@ static struct xps_map *expand_xps_map(struct xps_map *map, int attr_index,
 
 /* Must be called under cpus_read_lock */
 int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
-			  u16 index, bool is_rxqs_map)
+			  u16 index, enum xps_map_type type)
 {
 	struct xps_dev_maps *dev_maps, *new_dev_maps = NULL;
 	const unsigned long *online_mask = NULL;
@@ -2642,15 +2635,15 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 	}
 
 	mutex_lock(&xps_map_mutex);
-	if (is_rxqs_map) {
+
+	dev_maps = xmap_dereference(dev->xps_maps[type]);
+	if (type == XPS_RXQS) {
 		maps_sz = XPS_RXQ_DEV_MAPS_SIZE(num_tc, dev->num_rx_queues);
-		dev_maps = xmap_dereference(dev->xps_rxqs_map);
 		nr_ids = dev->num_rx_queues;
 	} else {
 		maps_sz = XPS_CPU_DEV_MAPS_SIZE(num_tc);
 		if (num_possible_cpus() > 1)
 			online_mask = cpumask_bits(cpu_online_mask);
-		dev_maps = xmap_dereference(dev->xps_cpus_map);
 		nr_ids = nr_cpu_ids;
 	}
 
@@ -2683,7 +2676,7 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 		tci = j * num_tc + tc;
 		map = copy ? xmap_dereference(dev_maps->attr_map[tci]) : NULL;
 
-		map = expand_xps_map(map, j, index, is_rxqs_map);
+		map = expand_xps_map(map, j, index, type == XPS_RXQS);
 		if (!map)
 			goto error;
 
@@ -2696,7 +2689,7 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 	if (!dev_maps) {
 		/* Increment static keys at most once per type */
 		static_key_slow_inc_cpuslocked(&xps_needed);
-		if (is_rxqs_map)
+		if (type == XPS_RXQS)
 			static_key_slow_inc_cpuslocked(&xps_rxqs_needed);
 	}
 
@@ -2725,7 +2718,7 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 			if (pos == map->len)
 				map->queues[map->len++] = index;
 #ifdef CONFIG_NUMA
-			if (!is_rxqs_map) {
+			if (type == XPS_CPUS) {
 				if (numa_node_id == -2)
 					numa_node_id = cpu_to_node(j);
 				else if (numa_node_id != cpu_to_node(j))
@@ -2746,10 +2739,7 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 		}
 	}
 
-	if (is_rxqs_map)
-		rcu_assign_pointer(dev->xps_rxqs_map, new_dev_maps);
-	else
-		rcu_assign_pointer(dev->xps_cpus_map, new_dev_maps);
+	rcu_assign_pointer(dev->xps_maps[type], new_dev_maps);
 
 	/* Cleanup old maps */
 	if (!dev_maps)
@@ -2778,12 +2768,11 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 	active = true;
 
 out_no_new_maps:
-	if (!is_rxqs_map) {
+	if (type == XPS_CPUS)
 		/* update Tx queue numa node */
 		netdev_queue_numa_node_write(netdev_get_tx_queue(dev, index),
 					     (numa_node_id >= 0) ?
 					     numa_node_id : NUMA_NO_NODE);
-	}
 
 	if (!dev_maps)
 		goto out_no_maps;
@@ -2801,7 +2790,7 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 
 	/* free map if not active */
 	if (!active)
-		reset_xps_maps(dev, dev_maps, is_rxqs_map);
+		reset_xps_maps(dev, dev_maps, type);
 
 out_no_maps:
 	mutex_unlock(&xps_map_mutex);
@@ -2833,7 +2822,7 @@ int netif_set_xps_queue(struct net_device *dev, const struct cpumask *mask,
 	int ret;
 
 	cpus_read_lock();
-	ret =  __netif_set_xps_queue(dev, cpumask_bits(mask), index, false);
+	ret =  __netif_set_xps_queue(dev, cpumask_bits(mask), index, XPS_CPUS);
 	cpus_read_unlock();
 
 	return ret;
@@ -3983,7 +3972,7 @@ static int get_xps_queue(struct net_device *dev, struct net_device *sb_dev,
 	if (!static_key_false(&xps_rxqs_needed))
 		goto get_cpus_map;
 
-	dev_maps = rcu_dereference(sb_dev->xps_rxqs_map);
+	dev_maps = rcu_dereference(sb_dev->xps_maps[XPS_RXQS]);
 	if (dev_maps) {
 		int tci = sk_rx_queue_get(sk);
 
@@ -3994,7 +3983,7 @@ static int get_xps_queue(struct net_device *dev, struct net_device *sb_dev,
 
 get_cpus_map:
 	if (queue_index < 0) {
-		dev_maps = rcu_dereference(sb_dev->xps_cpus_map);
+		dev_maps = rcu_dereference(sb_dev->xps_maps[XPS_CPUS]);
 		if (dev_maps) {
 			unsigned int tci = skb->sender_cpu - 1;
 
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index c762c435ff76..ca1f3b63cfad 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -1388,7 +1388,7 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue,
 	}
 
 	rcu_read_lock();
-	dev_maps = rcu_dereference(dev->xps_cpus_map);
+	dev_maps = rcu_dereference(dev->xps_maps[XPS_CPUS]);
 	nr_ids = dev_maps ? dev_maps->nr_ids : nr_cpu_ids;
 
 	mask = bitmap_zalloc(nr_ids, GFP_KERNEL);
@@ -1492,7 +1492,7 @@ static ssize_t xps_rxqs_show(struct netdev_queue *queue, char *buf)
 	}
 
 	rcu_read_lock();
-	dev_maps = rcu_dereference(dev->xps_rxqs_map);
+	dev_maps = rcu_dereference(dev->xps_maps[XPS_RXQS]);
 	nr_ids = dev_maps ? dev_maps->nr_ids : dev->num_rx_queues;
 
 	mask = bitmap_zalloc(nr_ids, GFP_KERNEL);
@@ -1566,7 +1566,7 @@ static ssize_t xps_rxqs_store(struct netdev_queue *queue, const char *buf,
 	}
 
 	cpus_read_lock();
-	err = __netif_set_xps_queue(dev, mask, index, true);
+	err = __netif_set_xps_queue(dev, mask, index, XPS_RXQS);
 	cpus_read_unlock();
 
 	rtnl_unlock();
-- 
2.30.2

[PATCH net-next v4 08/13] net: add an helper to copy xps maps to the new dev_maps

[Antoine Tenart]

This patch adds an helper, xps_copy_dev_maps, to copy maps from dev_maps
to new_dev_maps at a given index. The logic should be the same, with an
improved code readability and maintenance.

Signed-off-by: Antoine Tenart <atenart@kernel.org>
---
 net/core/dev.c | 45 +++++++++++++++++++++++++--------------------
 1 file changed, 25 insertions(+), 20 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index af57e32bb543..00f6b41e11d8 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2608,6 +2608,25 @@ static struct xps_map *expand_xps_map(struct xps_map *map, int attr_index,
 	return new_map;
 }
 
+/* Copy xps maps at a given index */
+static void xps_copy_dev_maps(struct xps_dev_maps *dev_maps,
+			      struct xps_dev_maps *new_dev_maps, int index,
+			      int tc, bool skip_tc)
+{
+	int i, tci = index * dev_maps->num_tc;
+	struct xps_map *map;
+
+	/* copy maps belonging to foreign traffic classes */
+	for (i = 0; i < dev_maps->num_tc; i++, tci++) {
+		if (i == tc && skip_tc)
+			continue;
+
+		/* fill in the new device map from the old device map */
+		map = xmap_dereference(dev_maps->attr_map[tci]);
+		RCU_INIT_POINTER(new_dev_maps->attr_map[tci], map);
+	}
+}
+
 /* Must be called under cpus_read_lock */
 int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 			  u16 index, enum xps_map_type type)
@@ -2694,23 +2713,16 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 	}
 
 	for (j = 0; j < nr_ids; j++) {
-		/* copy maps belonging to foreign traffic classes */
-		for (i = tc, tci = j * num_tc; copy && i--; tci++) {
-			/* fill in the new device map from the old device map */
-			map = xmap_dereference(dev_maps->attr_map[tci]);
-			RCU_INIT_POINTER(new_dev_maps->attr_map[tci], map);
-		}
+		bool skip_tc = false;
 
-		/* We need to explicitly update tci as prevous loop
-		 * could break out early if dev_maps is NULL.
-		 */
 		tci = j * num_tc + tc;
-
 		if (netif_attr_test_mask(j, mask, nr_ids) &&
 		    netif_attr_test_online(j, online_mask, nr_ids)) {
 			/* add tx-queue to CPU/rx-queue maps */
 			int pos = 0;
 
+			skip_tc = true;
+
 			map = xmap_dereference(new_dev_maps->attr_map[tci]);
 			while ((pos < map->len) && (map->queues[pos] != index))
 				pos++;
@@ -2725,18 +2737,11 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 					numa_node_id = -1;
 			}
 #endif
-		} else if (copy) {
-			/* fill in the new device map from the old device map */
-			map = xmap_dereference(dev_maps->attr_map[tci]);
-			RCU_INIT_POINTER(new_dev_maps->attr_map[tci], map);
 		}
 
-		/* copy maps belonging to foreign traffic classes */
-		for (i = num_tc - tc, tci++; copy && --i; tci++) {
-			/* fill in the new device map from the old device map */
-			map = xmap_dereference(dev_maps->attr_map[tci]);
-			RCU_INIT_POINTER(new_dev_maps->attr_map[tci], map);
-		}
+		if (copy)
+			xps_copy_dev_maps(dev_maps, new_dev_maps, j, tc,
+					  skip_tc);
 	}
 
 	rcu_assign_pointer(dev->xps_maps[type], new_dev_maps);
-- 
2.30.2

[PATCH net-next v4 09/13] net: improve queue removal readability in __netif_set_xps_queue

[Antoine Tenart]

Improve the readability of the loop removing tx-queue from unused
CPUs/rx-queues in __netif_set_xps_queue. The change should only be
cosmetic.

Signed-off-by: Antoine Tenart <atenart@kernel.org>
---
 net/core/dev.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index 00f6b41e11d8..c8ce2dfcc97d 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2784,13 +2784,16 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 
 	/* removes tx-queue from unused CPUs/rx-queues */
 	for (j = 0; j < dev_maps->nr_ids; j++) {
-		for (i = tc, tci = j * dev_maps->num_tc; i--; tci++)
-			active |= remove_xps_queue(dev_maps, tci, index);
-		if (!netif_attr_test_mask(j, mask, dev_maps->nr_ids) ||
-		    !netif_attr_test_online(j, online_mask, dev_maps->nr_ids))
-			active |= remove_xps_queue(dev_maps, tci, index);
-		for (i = dev_maps->num_tc - tc, tci++; --i; tci++)
+		tci = j * dev_maps->num_tc;
+
+		for (i = 0; i < dev_maps->num_tc; i++, tci++) {
+			if (i == tc &&
+			    netif_attr_test_mask(j, mask, dev_maps->nr_ids) &&
+			    netif_attr_test_online(j, online_mask, dev_maps->nr_ids))
+				continue;
+
 			active |= remove_xps_queue(dev_maps, tci, index);
+		}
 	}
 
 	/* free map if not active */
-- 
2.30.2

[PATCH net-next v4 10/13] net-sysfs: move the rtnl unlock up in the xps show helpers

[Antoine Tenart]

Now that nr_ids and num_tc are stored in the xps dev_maps, which are RCU
protected, we do not have the need to protect the maps in the rtnl lock.
Move the rtnl unlock up so we reduce the rtnl locking section.

We also increase the reference count on the subordinate device if any,
as we don't want this device to be freed while we use it (now that the
rtnl lock isn't protecting it in the whole function).

Signed-off-by: Antoine Tenart <atenart@kernel.org>
---
 net/core/net-sysfs.c | 25 +++++++++++--------------
 1 file changed, 11 insertions(+), 14 deletions(-)

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index ca1f3b63cfad..094fea082649 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -1383,10 +1383,14 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue,
 
 	tc = netdev_txq_to_tc(dev, index);
 	if (tc < 0) {
-		ret = -EINVAL;
-		goto err_rtnl_unlock;
+		rtnl_unlock();
+		return -EINVAL;
 	}
 
+	/* Make sure the subordinate device can't be freed */
+	get_device(&dev->dev);
+	rtnl_unlock();
+
 	rcu_read_lock();
 	dev_maps = rcu_dereference(dev->xps_maps[XPS_CPUS]);
 	nr_ids = dev_maps ? dev_maps->nr_ids : nr_cpu_ids;
@@ -1417,8 +1421,7 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue,
 	}
 out_no_maps:
 	rcu_read_unlock();
-
-	rtnl_unlock();
+	put_device(&dev->dev);
 
 	len = bitmap_print_to_pagebuf(false, buf, mask, nr_ids);
 	bitmap_free(mask);
@@ -1426,8 +1429,7 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue,
 
 err_rcu_unlock:
 	rcu_read_unlock();
-err_rtnl_unlock:
-	rtnl_unlock();
+	put_device(&dev->dev);
 	return ret;
 }
 
@@ -1486,10 +1488,9 @@ static ssize_t xps_rxqs_show(struct netdev_queue *queue, char *buf)
 		return restart_syscall();
 
 	tc = netdev_txq_to_tc(dev, index);
-	if (tc < 0) {
-		ret = -EINVAL;
-		goto err_rtnl_unlock;
-	}
+	rtnl_unlock();
+	if (tc < 0)
+		return -EINVAL;
 
 	rcu_read_lock();
 	dev_maps = rcu_dereference(dev->xps_maps[XPS_RXQS]);
@@ -1522,8 +1523,6 @@ static ssize_t xps_rxqs_show(struct netdev_queue *queue, char *buf)
 out_no_maps:
 	rcu_read_unlock();
 
-	rtnl_unlock();
-
 	len = bitmap_print_to_pagebuf(false, buf, mask, nr_ids);
 	bitmap_free(mask);
 
@@ -1531,8 +1530,6 @@ static ssize_t xps_rxqs_show(struct netdev_queue *queue, char *buf)
 
 err_rcu_unlock:
 	rcu_read_unlock();
-err_rtnl_unlock:
-	rtnl_unlock();
 	return ret;
 }
 
-- 
2.30.2

[PATCH net-next v4 11/13] net-sysfs: move the xps cpus/rxqs retrieval in a common function

[Antoine Tenart]

Most of the xps_cpus_show and xps_rxqs_show functions share the same
logic. Having it in two different functions does not help maintenance.
This patch moves their common logic into a new function, xps_queue_show,
to improve this.

Signed-off-by: Antoine Tenart <atenart@kernel.org>
---
 net/core/net-sysfs.c | 125 +++++++++++++++++--------------------------
 1 file changed, 48 insertions(+), 77 deletions(-)

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 094fea082649..562a42fcd437 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -1361,44 +1361,27 @@ static const struct attribute_group dql_group = {
 #endif /* CONFIG_BQL */
 
 #ifdef CONFIG_XPS
-static ssize_t xps_cpus_show(struct netdev_queue *queue,
-			     char *buf)
+static ssize_t xps_queue_show(struct net_device *dev, unsigned int index,
+			      int tc, char *buf, enum xps_map_type type)
 {
-	struct net_device *dev = queue->dev;
 	struct xps_dev_maps *dev_maps;
-	unsigned int index, nr_ids;
-	int j, len, ret, tc = 0;
 	unsigned long *mask;
-
-	if (!netif_is_multiqueue(dev))
-		return -ENOENT;
-
-	index = get_netdev_queue_index(queue);
-
-	if (!rtnl_trylock())
-		return restart_syscall();
-
-	/* If queue belongs to subordinate dev use its map */
-	dev = netdev_get_tx_queue(dev, index)->sb_dev ? : dev;
-
-	tc = netdev_txq_to_tc(dev, index);
-	if (tc < 0) {
-		rtnl_unlock();
-		return -EINVAL;
-	}
-
-	/* Make sure the subordinate device can't be freed */
-	get_device(&dev->dev);
-	rtnl_unlock();
+	unsigned int nr_ids;
+	int j, len;
 
 	rcu_read_lock();
-	dev_maps = rcu_dereference(dev->xps_maps[XPS_CPUS]);
-	nr_ids = dev_maps ? dev_maps->nr_ids : nr_cpu_ids;
+	dev_maps = rcu_dereference(dev->xps_maps[type]);
+
+	/* Default to nr_cpu_ids/dev->num_rx_queues and do not just return 0
+	 * when dev_maps hasn't been allocated yet, to be backward compatible.
+	 */
+	nr_ids = dev_maps ? dev_maps->nr_ids :
+		 (type == XPS_CPUS ? nr_cpu_ids : dev->num_rx_queues);
 
 	mask = bitmap_zalloc(nr_ids, GFP_KERNEL);
 	if (!mask) {
-		ret = -ENOMEM;
-		goto err_rcu_unlock;
+		rcu_read_unlock();
+		return -ENOMEM;
 	}
 
 	if (!dev_maps || tc >= dev_maps->num_tc)
@@ -1421,16 +1404,44 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue,
 	}
 out_no_maps:
 	rcu_read_unlock();
-	put_device(&dev->dev);
 
 	len = bitmap_print_to_pagebuf(false, buf, mask, nr_ids);
 	bitmap_free(mask);
+
 	return len < PAGE_SIZE ? len : -EINVAL;
+}
+
+static ssize_t xps_cpus_show(struct netdev_queue *queue, char *buf)
+{
+	struct net_device *dev = queue->dev;
+	unsigned int index;
+	int len, tc;
+
+	if (!netif_is_multiqueue(dev))
+		return -ENOENT;
+
+	index = get_netdev_queue_index(queue);
+
+	if (!rtnl_trylock())
+		return restart_syscall();
+
+	/* If queue belongs to subordinate dev use its map */
+	dev = netdev_get_tx_queue(dev, index)->sb_dev ? : dev;
+
+	tc = netdev_txq_to_tc(dev, index);
+	if (tc < 0) {
+		rtnl_unlock();
+		return -EINVAL;
+	}
+
+	/* Make sure the subordinate device can't be freed */
+	get_device(&dev->dev);
+	rtnl_unlock();
+
+	len = xps_queue_show(dev, index, tc, buf, XPS_CPUS);
 
-err_rcu_unlock:
-	rcu_read_unlock();
 	put_device(&dev->dev);
-	return ret;
+	return len;
 }
 
 static ssize_t xps_cpus_store(struct netdev_queue *queue,
@@ -1477,10 +1488,8 @@ static struct netdev_queue_attribute xps_cpus_attribute __ro_after_init
 static ssize_t xps_rxqs_show(struct netdev_queue *queue, char *buf)
 {
 	struct net_device *dev = queue->dev;
-	struct xps_dev_maps *dev_maps;
-	unsigned int index, nr_ids;
-	int j, len, ret, tc = 0;
-	unsigned long *mask;
+	unsigned int index;
+	int tc;
 
 	index = get_netdev_queue_index(queue);
 
@@ -1492,45 +1501,7 @@ static ssize_t xps_rxqs_show(struct netdev_queue *queue, char *buf)
 	if (tc < 0)
 		return -EINVAL;
 
-	rcu_read_lock();
-	dev_maps = rcu_dereference(dev->xps_maps[XPS_RXQS]);
-	nr_ids = dev_maps ? dev_maps->nr_ids : dev->num_rx_queues;
-
-	mask = bitmap_zalloc(nr_ids, GFP_KERNEL);
-	if (!mask) {
-		ret = -ENOMEM;
-		goto err_rcu_unlock;
-	}
-
-	if (!dev_maps || tc >= dev_maps->num_tc)
-		goto out_no_maps;
-
-	for (j = 0; j < nr_ids; j++) {
-		int i, tci = j * dev_maps->num_tc + tc;
-		struct xps_map *map;
-
-		map = rcu_dereference(dev_maps->attr_map[tci]);
-		if (!map)
-			continue;
-
-		for (i = map->len; i--;) {
-			if (map->queues[i] == index) {
-				set_bit(j, mask);
-				break;
-			}
-		}
-	}
-out_no_maps:
-	rcu_read_unlock();
-
-	len = bitmap_print_to_pagebuf(false, buf, mask, nr_ids);
-	bitmap_free(mask);
-
-	return len < PAGE_SIZE ? len : -EINVAL;
-
-err_rcu_unlock:
-	rcu_read_unlock();
-	return ret;
+	return xps_queue_show(dev, index, tc, buf, XPS_RXQS);
 }
 
 static ssize_t xps_rxqs_store(struct netdev_queue *queue, const char *buf,
-- 
2.30.2

[PATCH net-next v4 12/13] net: fix use after free in xps

[Antoine Tenart]

When setting up an new dev_maps in __netif_set_xps_queue, we remove and
free maps from unused CPUs/rx-queues near the end of the function; by
calling remove_xps_queue. However it's possible those maps are also part
of the old not-freed-yet dev_maps, which might be used concurrently.
When that happens, a map can be freed while its corresponding entry in
the old dev_maps table isn't NULLed, leading to: "BUG: KASAN:
use-after-free" in different places.

This fixes the map freeing logic for unused CPUs/rx-queues, to also NULL
the map entries from the old dev_maps table.

Signed-off-by: Antoine Tenart <atenart@kernel.org>
---
 net/core/dev.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index c8ce2dfcc97d..d5f6ba209f1e 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2460,7 +2460,7 @@ static DEFINE_MUTEX(xps_map_mutex);
 	rcu_dereference_protected((P), lockdep_is_held(&xps_map_mutex))
 
 static bool remove_xps_queue(struct xps_dev_maps *dev_maps,
-			     int tci, u16 index)
+			     struct xps_dev_maps *old_maps, int tci, u16 index)
 {
 	struct xps_map *map = NULL;
 	int pos;
@@ -2479,6 +2479,8 @@ static bool remove_xps_queue(struct xps_dev_maps *dev_maps,
 			break;
 		}
 
+		if (old_maps)
+			RCU_INIT_POINTER(old_maps->attr_map[tci], NULL);
 		RCU_INIT_POINTER(dev_maps->attr_map[tci], NULL);
 		kfree_rcu(map, rcu);
 		return false;
@@ -2499,7 +2501,7 @@ static bool remove_xps_queue_cpu(struct net_device *dev,
 		int i, j;
 
 		for (i = count, j = offset; i--; j++) {
-			if (!remove_xps_queue(dev_maps, tci, j))
+			if (!remove_xps_queue(dev_maps, NULL, tci, j))
 				break;
 		}
 
@@ -2631,7 +2633,7 @@ static void xps_copy_dev_maps(struct xps_dev_maps *dev_maps,
 int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 			  u16 index, enum xps_map_type type)
 {
-	struct xps_dev_maps *dev_maps, *new_dev_maps = NULL;
+	struct xps_dev_maps *dev_maps, *new_dev_maps = NULL, *old_dev_maps = NULL;
 	const unsigned long *online_mask = NULL;
 	bool active = false, copy = false;
 	int i, j, tci, numa_node_id = -2;
@@ -2766,7 +2768,7 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 		}
 	}
 
-	kfree_rcu(dev_maps, rcu);
+	old_dev_maps = dev_maps;
 
 out_no_old_maps:
 	dev_maps = new_dev_maps;
@@ -2792,10 +2794,15 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 			    netif_attr_test_online(j, online_mask, dev_maps->nr_ids))
 				continue;
 
-			active |= remove_xps_queue(dev_maps, tci, index);
+			active |= remove_xps_queue(dev_maps,
+						   copy ? old_dev_maps : NULL,
+						   tci, index);
 		}
 	}
 
+	if (old_dev_maps)
+		kfree_rcu(old_dev_maps, rcu);
+
 	/* free map if not active */
 	if (!active)
 		reset_xps_maps(dev, dev_maps, type);
-- 
2.30.2

[PATCH net-next v4 13/13] net: NULL the old xps map entries when freeing them

[Antoine Tenart]

In __netif_set_xps_queue, old map entries from the old dev_maps are
freed but their corresponding entry in the old dev_maps aren't NULLed.
Fix this.

Signed-off-by: Antoine Tenart <atenart@kernel.org>
---
 net/core/dev.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/core/dev.c b/net/core/dev.c
index d5f6ba209f1e..4961fc2e9b19 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2764,6 +2764,7 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 					continue;
 			}
 
+			RCU_INIT_POINTER(dev_maps->attr_map[tci], NULL);
 			kfree_rcu(map, rcu);
 		}
 	}
-- 
2.30.2

Re: [PATCH net-next v4 00/13] net: xps: improve the xps maps handling

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net-next.git (refs/heads/master):

On Thu, 18 Mar 2021 19:37:39 +0100 you wrote:
> Hello,
> 
> This series aims at fixing various issues with the xps code, including
> out-of-bound accesses and use-after-free. While doing so we try to
> improve the xps code maintainability and readability.
> 
> The main change is moving dev->num_tc and dev->nr_ids in the xps maps, to
> avoid out-of-bound accesses as those two fields can be updated after the
> maps have been allocated. This allows further reworks, to improve the
> xps code readability and allow to stop taking the rtnl lock when
> reading the maps in sysfs. The maps are moved to an array in net_device,
> which simplifies the code a lot.
> 
> [...]

Here is the summary with links:
  - [net-next,v4,01/13] net-sysfs: convert xps_cpus_show to bitmap_zalloc
    https://git.kernel.org/netdev/net-next/c/ea4fe7e842f6
  - [net-next,v4,02/13] net-sysfs: store the return of get_netdev_queue_index in an unsigned int
    https://git.kernel.org/netdev/net-next/c/d9a063d207f0
  - [net-next,v4,03/13] net-sysfs: make xps_cpus_show and xps_rxqs_show consistent
    https://git.kernel.org/netdev/net-next/c/73f5e52b15e3
  - [net-next,v4,04/13] net: embed num_tc in the xps maps
    https://git.kernel.org/netdev/net-next/c/255c04a87f43
  - [net-next,v4,05/13] net: embed nr_ids in the xps maps
    https://git.kernel.org/netdev/net-next/c/5478fcd0f483
  - [net-next,v4,06/13] net: remove the xps possible_mask
    https://git.kernel.org/netdev/net-next/c/6f36158e0584
  - [net-next,v4,07/13] net: move the xps maps to an array
    https://git.kernel.org/netdev/net-next/c/044ab86d431b
  - [net-next,v4,08/13] net: add an helper to copy xps maps to the new dev_maps
    https://git.kernel.org/netdev/net-next/c/402fbb992e13
  - [net-next,v4,09/13] net: improve queue removal readability in __netif_set_xps_queue
    https://git.kernel.org/netdev/net-next/c/132f743b01b8
  - [net-next,v4,10/13] net-sysfs: move the rtnl unlock up in the xps show helpers
    https://git.kernel.org/netdev/net-next/c/d7be87a687cc
  - [net-next,v4,11/13] net-sysfs: move the xps cpus/rxqs retrieval in a common function
    https://git.kernel.org/netdev/net-next/c/2db6cdaebac8
  - [net-next,v4,12/13] net: fix use after free in xps
    https://git.kernel.org/netdev/net-next/c/2d05bf015308
  - [net-next,v4,13/13] net: NULL the old xps map entries when freeing them
    https://git.kernel.org/netdev/net-next/c/75b2758abc35

You are awesome, thank you!
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