Avoid iwlwifi hardware scanning race conditions that may lead to not call ieee80211_scan_completed() (what in consequences gives "WARNING: at net/wireless/core.c:614 wdev_cleanup_work+0xb7/0xf0"), or call iee80211_scan_completed() more then once (what gives " WARNING: at net/mac80211/scan.c:312 ieee80211_scan_completed+0x5f/0x1f1"). First problem (warning in wdev_cleanup_work) make any further scan request from cfg80211 are ignored by mac80211 with EBUSY error, hence NetworkManager can not perform successful scan and not allow to establish a new connection. So after suspend/resume (but maybe not only then) user is not able to connect to wireless network again. We can not rely on that the commands (start and abort scan) are successful. Even if they are successfully send to the hardware, we can not get back notification from firmware (i.e. firmware hung or was reseted), or we can get notification when we actually perform abort scan in driver code or after that. To assure we call ieee80211_scan_completed() only once when scan was started we use SCAN_SCANNING bit. Code path, which first clear STATUS_SCANNING bit will call ieee80211_scan_completed(). We do this in many cases, in scan complete notification, scan abort, device down, etc. Each time we check SCANNING bit. Tested on 3945, 4965 and 5300 adapters. Tested normal work functionality and doing scan stress testing using scripts: http://people.redhat.com/sgruszka/misc/test_wifi_scan_reboot.sh http://people.redhat.com/sgruszka/misc/test_wifi_scan_updown.sh v1 -> v2: - fix not cleared STATUS_SCAN_HW bit in patch 2 - merged patch 7 and 8 - add 3 new patches v2 -> v3: - merged patch 5 and 14 - merged patch 2 and 16 - add bugzilla reference into 3 most important patches - not use cancel_delayed_work_sync in work function (patch 10) v3 -> v4: - add additional changelog comments in patch 9 and 13 and Wey acks in other patches -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
