From bf17b36ccdd5b7b9dd482d7753bcb9aff2d21d39 Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Wed, 6 Dec 2023 17:21:23 +0100 Subject: [PATCH] net: sysfs: fix locking in carrier read My previous patch added a call to linkwatch_sync_dev(), but that of course needs to be called under RTNL, which I missed earlier, but now saw RCU warnings from. Fix that by acquiring the RTNL in a similar fashion to how other files do it here. Fixes: facd15dfd691 ("net: core: synchronize link-watch when carrier is queried") Signed-off-by: Johannes Berg Link: https://lore.kernel.org/r/20231206172122.859df6ba937f.I9c80608bcfbab171943ff4942b52dbd5e97fe06e@changeid Signed-off-by: Jakub Kicinski --- net/core/net-sysfs.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c index d9b33e923b187..a09d507c5b03d 100644 --- a/net/core/net-sysfs.c +++ b/net/core/net-sysfs.c @@ -193,6 +193,10 @@ static ssize_t carrier_show(struct device *dev, struct device_attribute *attr, char *buf) { struct net_device *netdev = to_net_dev(dev); + int ret = -EINVAL; + + if (!rtnl_trylock()) + return restart_syscall(); if (netif_running(netdev)) { /* Synchronize carrier state with link watch, @@ -200,10 +204,11 @@ static ssize_t carrier_show(struct device *dev, */ linkwatch_sync_dev(netdev); - return sysfs_emit(buf, fmt_dec, !!netif_carrier_ok(netdev)); + ret = sysfs_emit(buf, fmt_dec, !!netif_carrier_ok(netdev)); } + rtnl_unlock(); - return -EINVAL; + return ret; } static DEVICE_ATTR_RW(carrier); -- 2.30.2