Hi,
Since commit 52e04b4ce5d0 ("mac80211: fix race in
ieee80211_register_hw()") the debugfs entries for mac80211 drivers are
broken.
https://git.kernel.org/linus/52e04b4ce5d03775b6a78f3ed1097480faacc9fd
Felix reported that the file /sys/kernel/debug/ieee80211/phy0/rc is now
located at /sys/kernel/debug/rc.
Before this commit we had the following flow:
1. wiphy_register()
-> creates /sys/kernel/debug/ieee80211/phy0/
-> fill rdev->wiphy.debugfsdir pointer
2. ieee80211_init_rate_ctrl_alg()
-> call rate_control_alloc()
-> use rdev->wiphy.debugfsdir pointer to
create /sys/kernel/debug/ieee80211/phy0/rc/
This works like expected.
With the commit the flow in ieee80211_register_hw() is the other way around:
2. ieee80211_init_rate_ctrl_alg()
-> call rate_control_alloc()
-> use rdev->wiphy.debugfsdir pointer (now NULL) to
create /sys/kernel/debug/rc/
2. wiphy_register()
-> creates /sys/kernel/debug/ieee80211/phy0/
-> fill rdev->wiphy.debugfsdir pointer
This patch was backported to multiple stable kernel versions:
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-5.4.y&id=a8ce3412e8a22279e1bdc81c3c2bacd3785c1577
Hauke
