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authorAlexander Duyck <alexanderduyck@fb.com>2021-02-08 14:29:18 -0800
committerDavid S. Miller <davem@davemloft.net>2021-02-08 15:07:50 -0800
commitb2f175648031b8b22927220abd3b081f1a12e628 (patch)
tree480dae4449566e4c465065a9cd26bcde1c7dcdf8 /net/core
parent796c9015ab8d41a66e35fb45c61c60676fc7dc41 (diff)
net-sysfs: Add rtnl locking for getting Tx queue traffic class
In order to access the suboordinate dev for a device we should be holding the rtnl_lock when outside of the transmit path. The existing code was not doing that for the sysfs dump function and as a result we were open to a possible race. To resolve that take the rtnl lock prior to accessing the sb_dev field of the Tx queue and release it after we have retrieved the tc for the queue. Signed-off-by: Alexander Duyck <alexanderduyck@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core')
-rw-r--r--net/core/net-sysfs.c13
1 files changed, 10 insertions, 3 deletions
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index daf502c13d6d..91afb0b6de69 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -1136,18 +1136,25 @@ static ssize_t traffic_class_show(struct netdev_queue *queue,
char *buf)
{
struct net_device *dev = queue->dev;
+ int num_tc, tc;
int index;
- int tc;
if (!netif_is_multiqueue(dev))
return -ENOENT;
+ if (!rtnl_trylock())
+ return restart_syscall();
+
index = get_netdev_queue_index(queue);
/* If queue belongs to subordinate dev use its TC mapping */
dev = netdev_get_tx_queue(dev, index)->sb_dev ? : dev;
+ num_tc = dev->num_tc;
tc = netdev_txq_to_tc(dev, index);
+
+ rtnl_unlock();
+
if (tc < 0)
return -EINVAL;
@@ -1158,8 +1165,8 @@ static ssize_t traffic_class_show(struct netdev_queue *queue,
* belongs to the root device it will be reported with just the
* traffic class, so just "0" for TC 0 for example.
*/
- return dev->num_tc < 0 ? sprintf(buf, "%d%d\n", tc, dev->num_tc) :
- sprintf(buf, "%d\n", tc);
+ return num_tc < 0 ? sprintf(buf, "%d%d\n", tc, num_tc) :
+ sprintf(buf, "%d\n", tc);
}
#ifdef CONFIG_XPS