On Mon, 2010-09-13 at 05:46 -0700, Stanislaw Gruszka wrote: > 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 Thank you, looks good to me. Wey -- 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
