From: Ilan Peer <ilan.peer@xxxxxxxxx> [ Upstream commit 45daaa1318410794de956fb8e9d06aed2dbb23d0 ] The following race was possible: 1. The device driver requests HW restart. 2. A scan is requested from user space and is propagated to the driver. During this flow HW_SCANNING flag is set. 3. The thread that handles the HW restart is scheduled, and before starting the actual reconfiguration it checks that HW_SCANNING is not set. The flow does so without acquiring any lock, and thus the WARN fires. Fix this by checking that HW_SCANNING is on only after RTNL is acquired, i.e., user space scan request handling is no longer in transit. Signed-off-by: Ilan Peer <ilan.peer@xxxxxxxxx> Signed-off-by: Luca Coelho <luciano.coelho@xxxxxxxxx> Link: https://lore.kernel.org/r/iwlwifi.20210618133832.8238ab3e19ab.I2693c581c70251472b4f9089e37e06fb2c18268f@changeid Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- net/mac80211/main.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/net/mac80211/main.c b/net/mac80211/main.c index f33a3acd7f96..2481bfdfafd0 100644 --- a/net/mac80211/main.c +++ b/net/mac80211/main.c @@ -257,14 +257,13 @@ static void ieee80211_restart_work(struct work_struct *work) /* wait for scan work complete */ flush_workqueue(local->workqueue); flush_work(&local->sched_scan_stopped_work); + flush_work(&local->radar_detected_work); + + rtnl_lock(); WARN(test_bit(SCAN_HW_SCANNING, &local->scanning), "%s called with hardware scan in progress\n", __func__); - flush_work(&local->radar_detected_work); - /* we might do interface manipulations, so need both */ - rtnl_lock(); - wiphy_lock(local->hw.wiphy); list_for_each_entry(sdata, &local->interfaces, list) { /* * XXX: there may be more work for other vif types and even -- 2.30.2
