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 | |
| 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')
| -rw-r--r-- | net/core/dev.c | 2 | ||||
| -rw-r--r-- | net/core/dev.h | 1 | ||||
| -rw-r--r-- | net/core/link_watch.c | 2 | ||||
| -rw-r--r-- | net/core/net-sysfs.c | 8 | ||||
| -rw-r--r-- | net/core/rtnetlink.c | 8 |
5 files changed, 17 insertions, 4 deletions
diff --git a/net/core/dev.c b/net/core/dev.c index c5679dfbaa70..0432b04cf9b0 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -10548,7 +10548,7 @@ void netdev_run_todo(void) write_lock(&dev_base_lock); dev->reg_state = NETREG_UNREGISTERED; write_unlock(&dev_base_lock); - linkwatch_forget_dev(dev); + linkwatch_sync_dev(dev); } while (!list_empty(&list)) { diff --git a/net/core/dev.h b/net/core/dev.h index 7795b8ad841d..cf93e188785b 100644 --- a/net/core/dev.h +++ b/net/core/dev.h @@ -30,7 +30,6 @@ int __init dev_proc_init(void); #endif void linkwatch_init_dev(struct net_device *dev); -void linkwatch_forget_dev(struct net_device *dev); void linkwatch_run_queue(void); void dev_addr_flush(struct net_device *dev); diff --git a/net/core/link_watch.c b/net/core/link_watch.c index c469d1c4db5d..a19f21403339 100644 --- a/net/core/link_watch.c +++ b/net/core/link_watch.c @@ -245,7 +245,7 @@ static void __linkwatch_run_queue(int urgent_only) spin_unlock_irq(&lweventlist_lock); } -void linkwatch_forget_dev(struct net_device *dev) +void linkwatch_sync_dev(struct net_device *dev) { unsigned long flags; int clean = 0; 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; } diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index 592164c2a540..5e0ab4c08f72 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -3853,6 +3853,14 @@ static int rtnl_getlink(struct sk_buff *skb, struct nlmsghdr *nlh, if (nskb == NULL) goto out; + /* Synchronize the carrier state so we don't report a state + * that we're not actually going to honour immediately; if + * the driver just did a carrier off->on transition, we can + * only TX if link watch work has run, but without this we'd + * already report carrier on, even if it doesn't work yet. + */ + linkwatch_sync_dev(dev); + err = rtnl_fill_ifinfo(nskb, dev, net, RTM_NEWLINK, NETLINK_CB(skb).portid, nlh->nlmsg_seq, 0, 0, ext_filter_mask, |