Call to ieee80211_color_collision_detection_work() needs wiphy lock to be
held. This lock cannot be taken directly in the delayed work because it
would cause a potential deadlock. Indeed ieee80211_link_stop() is calling
cancel_delayed_work_sync() with the lock held. To avoid such deadlock one
can use a wiphy delayed work instead.
Thus this patchset convert ieee80211_color_collision_detection_work() to
use wiphy delayed work instead of classical delayed work. But because
this work is used to ratelimit cfg80211_obss_color_collision_notify() a
way to tell if it has already been scheduled is needed as discussed in
[0]. In this thread three different solutions has been considered:
- Implementing wiphy_delayed_work_pending() to detect if work can be
queued without postponing a previous schedule
- Using a __ratelimit or an equivalent to queue the work
- Modifying wiphy_delayed_work_queue() to mimic queue_delayed_work() by
not queuing the work if already queued (while also possibly having to
add wiphy_delayed_work_mod() for those who need the mod_delayed_work()
behavior).
This patchset implement the first solution.
[0]: https://lore.kernel.org/linux-wireless/D4A40Q44OAY2.W3SIF6UEPBUN@xxxxxxxxxx/
Remi Pommarel (2):
wifi: cfg80211: Add wiphy_delayed_work_pending()
wifi: mac80211: Convert color collision detection to wiphy work
include/net/cfg80211.h | 44 ++++++++++++++++++++++++++++++++++++++
net/mac80211/cfg.c | 17 ++++++++-------
net/mac80211/ieee80211_i.h | 5 +++--
net/mac80211/link.c | 7 +++---
net/wireless/core.c | 7 ++++++
5 files changed, 67 insertions(+), 13 deletions(-)
--
2.46.0
