mac80211: Properly WARN on HW scan before restart
authorIlan Peer <ilan.peer@intel.com>
Fri, 18 Jun 2021 10:41:37 +0000 (13:41 +0300)
committerJohannes Berg <johannes.berg@intel.com>
Wed, 23 Jun 2021 09:29:14 +0000 (11:29 +0200)
commit45daaa1318410794de956fb8e9d06aed2dbb23d0
treefc22b2a47304fdd7e0577d5b7f4a59de6a3c356f
parentdd3e4fc75b4ab8186a133cfe9d49666a2f8186e0
mac80211: Properly WARN on HW scan before restart

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@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20210618133832.8238ab3e19ab.I2693c581c70251472b4f9089e37e06fb2c18268f@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
net/mac80211/main.c