From d7be87a687cc261d663dcf97c01056f71398f9f9 Mon Sep 17 00:00:00 2001 From: Antoine Tenart Date: Thu, 18 Mar 2021 19:37:49 +0100 Subject: [PATCH] net-sysfs: move the rtnl unlock up in the xps show helpers 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 Signed-off-by: David S. Miller --- 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 ca1f3b6..094fea0 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 @@ out_no_maps: 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 @@ out_no_maps: err_rcu_unlock: rcu_read_unlock(); -err_rtnl_unlock: - rtnl_unlock(); return ret; } -- 2.7.4