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Message-Id: <20201221193644.1296933-3-atenart@kernel.org>
Date: Mon, 21 Dec 2020 20:36:43 +0100
From: Antoine Tenart <atenart@...nel.org>
To: davem@...emloft.net, kuba@...nel.org, alexander.duyck@...il.com
Cc: Antoine Tenart <atenart@...nel.org>, netdev@...r.kernel.org,
pabeni@...hat.com
Subject: [PATCH net v2 2/3] net: move the xps cpus retrieval out of net-sysfs
Accesses to dev->xps_cpus_map (when using dev->num_tc) should be
protected by the xps_map mutex, to avoid possible race conditions when
dev->num_tc is updated while the map is accessed. This patch moves the
logic accessing dev->xps_cpu_map and dev->num_tc to net/core/dev.c,
where the xps_map mutex is defined and used.
Fixes: 184c449f91fe ("net: Add support for XPS with QoS via traffic classes")
Signed-off-by: Antoine Tenart <atenart@...nel.org>
---
include/linux/netdevice.h | 8 ++++++
net/core/dev.c | 59 +++++++++++++++++++++++++++++++++++++++
net/core/net-sysfs.c | 54 ++++++++---------------------------
3 files changed, 79 insertions(+), 42 deletions(-)
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 259be67644e3..bfd6cfa3ea90 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -3671,6 +3671,8 @@ 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);
+int netif_show_xps_queue(struct net_device *dev, unsigned long **mask,
+ u16 index);
/**
* netif_attr_test_mask - Test a CPU or Rx queue set in a mask
@@ -3769,6 +3771,12 @@ static inline int __netif_set_xps_queue(struct net_device *dev,
{
return 0;
}
+
+static inline int netif_show_xps_queue(struct net_device *dev,
+ unsigned long **mask, u16 index)
+{
+ return 0;
+}
#endif
/**
diff --git a/net/core/dev.c b/net/core/dev.c
index effdb7fee9df..a0257da4160a 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2831,6 +2831,65 @@ int netif_set_xps_queue(struct net_device *dev, const struct cpumask *mask,
}
EXPORT_SYMBOL(netif_set_xps_queue);
+int netif_show_xps_queue(struct net_device *dev, unsigned long **mask,
+ u16 index)
+{
+ const unsigned long *possible_mask = NULL;
+ int j, num_tc = 1, tc = 0, ret = 0;
+ struct xps_dev_maps *dev_maps;
+ unsigned int nr_ids;
+
+ rcu_read_lock();
+ mutex_lock(&xps_map_mutex);
+
+ if (dev->num_tc) {
+ num_tc = dev->num_tc;
+ if (num_tc < 0) {
+ ret = -EINVAL;
+ goto out_no_map;
+ }
+
+ /* 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 out_no_map;
+ }
+ }
+
+ dev_maps = rcu_dereference(dev->xps_cpus_map);
+ if (!dev_maps)
+ goto out_no_map;
+ nr_ids = nr_cpu_ids;
+ if (num_possible_cpus() > 1)
+ possible_mask = cpumask_bits(cpu_possible_mask);
+
+ for (j = -1; j = netif_attrmask_next(j, possible_mask, nr_ids),
+ j < nr_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_map:
+ mutex_unlock(&xps_map_mutex);
+ rcu_read_unlock();
+
+ return ret;
+}
+EXPORT_SYMBOL(netif_show_xps_queue);
#endif
static void __netdev_unbind_sb_channel(struct net_device *dev,
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 999b70c59761..29ee69b67972 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -1314,60 +1314,30 @@ 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_cpus_show(struct netdev_queue *queue, char *buf)
{
struct net_device *dev = queue->dev;
- int cpu, len, num_tc = 1, tc = 0;
- struct xps_dev_maps *dev_maps;
- cpumask_var_t mask;
- unsigned long index;
+ unsigned long *mask, index;
+ int len, ret;
if (!netif_is_multiqueue(dev))
return -ENOENT;
index = get_netdev_queue_index(queue);
- if (dev->num_tc) {
- /* Do not allow XPS on subordinate device directly */
- num_tc = dev->num_tc;
- if (num_tc < 0)
- return -EINVAL;
-
- /* 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)
- return -EINVAL;
- }
-
- if (!zalloc_cpumask_var(&mask, GFP_KERNEL))
+ mask = bitmap_zalloc(nr_cpu_ids, GFP_KERNEL);
+ if (!mask)
return -ENOMEM;
- 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) {
- cpumask_set_cpu(cpu, mask);
- break;
- }
- }
- }
+ ret = netif_show_xps_queue(dev, &mask, index);
+ if (ret) {
+ bitmap_free(mask);
+ return ret;
}
- rcu_read_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;
}
--
2.29.2
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