diff options
| author | Johannes Berg <johannes.berg@intel.com> | 2023-12-04 21:47:07 +0100 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2023-12-05 20:16:45 -0800 |
| commit | facd15dfd69122042502d99ab8c9f888b48ee994 (patch) | |
| tree | 1e84133ba27f60f62134588c7cce46dc73badc31 /net/core/net-sysfs.c | |
| parent | faf4cf7495431d396147d5c73a84ccfddc458c9d (diff) | |
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 <johannes.berg@intel.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Link: https://lore.kernel.org/r/20231204214706.303c62768415.I1caedccae72ee5a45c9085c5eb49c145ce1c0dd5@changeid
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/core/net-sysfs.c')
| -rw-r--r-- | net/core/net-sysfs.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c index fccaa5bac0ed..d9b33e923b18 100644 --- a/net/core/net-sysfs.c +++ b/net/core/net-sysfs.c @@ -194,8 +194,14 @@ static ssize_t carrier_show(struct device *dev, { struct net_device *netdev = to_net_dev(dev); - if (netif_running(netdev)) + if (netif_running(netdev)) { + /* Synchronize carrier state with link watch, + * see also rtnl_getlink(). + */ + linkwatch_sync_dev(netdev); + return sysfs_emit(buf, fmt_dec, !!netif_carrier_ok(netdev)); + } return -EINVAL; } |