From facd15dfd69122042502d99ab8c9f888b48ee994 Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Mon, 4 Dec 2023 21:47:07 +0100 Subject: net: core: synchronize link-watch when carrier is queried There are multiple ways to query for the carrier state: through rtnetlink, sysfs, and (possibly) ethtool. Synchronize linkwatch work before these operations so that we don't have a situation where userspace queries the carrier state between the driver's carrier off->on transition and linkwatch running and expects it to work, when really (at least) TX cannot work until linkwatch has run. I previously posted a longer explanation of how this applies to wireless [1] but with this wireless can simply query the state before sending data, to ensure the kernel is ready for it. [1] https://lore.kernel.org/all/346b21d87c69f817ea3c37caceb34f1f56255884.camel@sipsolutions.net/ Signed-off-by: Johannes Berg Reviewed-by: Jiri Pirko Link: https://lore.kernel.org/r/20231204214706.303c62768415.I1caedccae72ee5a45c9085c5eb49c145ce1c0dd5@changeid Signed-off-by: Jakub Kicinski --- net/ethtool/ioctl.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'net/ethtool') diff --git a/net/ethtool/ioctl.c b/net/ethtool/ioctl.c index 0b0ce4f81c01..a977f8903467 100644 --- a/net/ethtool/ioctl.c +++ b/net/ethtool/ioctl.c @@ -58,6 +58,9 @@ static struct devlink *netdev_to_devlink_get(struct net_device *dev) u32 ethtool_op_get_link(struct net_device *dev) { + /* Synchronize carrier state with link watch, see also rtnl_getlink() */ + linkwatch_sync_dev(dev); + return netif_carrier_ok(dev) ? 1 : 0; } EXPORT_SYMBOL(ethtool_op_get_link); -- cgit