testing enviroment:
4965 card
commit 28aba7a8b5b926c4260bffbc5323ee933e2c4688
Fedora 10 (64bit)
Cisco 1250 AP

problem:
file transfer stalled on 802.11n mode 2.4GHz band, and saw "WARNING: at
net/mac80211/agg-tx.c:142" and Call trace. 
802.11n mode on 5GHz band works well.  

steps:
1. configure AP working on 802.11n mode 2.4GHz band
2. connecting STA to AP
3. on server: scp 300Mfile <STA>:/tmp
 ---> 2% 6420KB 511.0KB/s - stalled 
4. dmesg

------------[ cut here ]------------
WARNING: at net/mac80211/agg-tx.c:142 ___ieee80211_stop_tx_ba_session+0x61/0x71
[mac80211]()
Hardware name: Santa Rosa platform
Modules linked in: iwlagn iwlcore mac80211 bridge stp bnep sco l2cap bluetooth
sunrpc ipt_REJECT nf_conntrack_ipv4 nf_defrag_ipv4 iptable_filter ip_tables
ip6t_REJECT xt_tcpudp nf_conntrack_ipv6 xt_state nf_conntrack ip6table_filter
ip6_tables x_tables ipv6 cpufreq_ondemand acpi_cpufreq dm_mirror dm_region_hash
dm_log dm_multipath dm_mod uinput snd_hda_intel snd_hda_codec snd_hwdep
snd_seq_dummy snd_seq_oss snd_seq_midi_event snd_seq snd_seq_device snd_pcm_oss
snd_mixer_oss snd_pcm sr_mod snd_timer snd cdrom iTCO_wdt iTCO_vendor_support
soundcore snd_page_alloc battery e1000e i2c_i801 i2c_core sg ac video output
button pcspkr ata_generic ata_piix libata sd_mod scsi_mod ext3 jbd mbcache
uhci_hcd ohci_hcd ehci_hcd [last unloaded: mac80211]
Pid: 4376, comm: phy6 Tainted: G        W  2.6.30-rc4-wl #2
Call Trace:
 [<ffffffff8103ad2e>] ? warn_slowpath+0xcd/0xff
 [<ffffffffa05193a0>] ? iwl_find_station+0x145/0x155 [iwlcore]
 [<ffffffffa0513618>] ? iwl_tx_agg_stop+0xc0/0x2b4 [iwlcore]
 [<ffffffffa0535fff>] ? iwl_mac_ampdu_action+0x2a1/0x327 [iwlagn]
 [<ffffffff8103b19a>] ? release_console_sem+0x3e/0x1ce
 [<ffffffffa04d1ad3>] ? ___ieee80211_stop_tx_ba_session+0x61/0x71 [mac80211]
 [<ffffffffa04d1c41>] ? __ieee80211_stop_tx_ba_session+0x58/0x6d [mac80211]
 [<ffffffffa04d18e3>] ? ieee80211_sta_tear_down_BA_sessions+0x1a/0x37
[mac80211]
 [<ffffffffa04d48c9>] ? ieee80211_set_disassoc+0xe6/0x2bc [mac80211]
 [<ffffffffa04d47e3>] ? ieee80211_set_disassoc+0x0/0x2bc [mac80211]
 [<ffffffff81044218>] ? mod_timer+0xd6/0xe4
 [<ffffffffa04d724c>] ? ieee80211_sta_work+0x35c/0x8ec [mac80211]
 [<ffffffff8104a603>] ? worker_thread+0x18e/0x2ea
 [<ffffffff8104a657>] ? worker_thread+0x1e2/0x2ea
 [<ffffffff8104a603>] ? worker_thread+0x18e/0x2ea
 [<ffffffffa04d6ef0>] ? ieee80211_sta_work+0x0/0x8ec [mac80211]
 [<ffffffff8104e2df>] ? autoremove_wake_function+0x0/0x2e
 [<ffffffff8104a475>] ? worker_thread+0x0/0x2ea
 [<ffffffff8104a475>] ? worker_thread+0x0/0x2ea
 [<ffffffff8104df3f>] ? kthread+0x54/0x80
 [<ffffffff812df3f3>] ? trace_hardirqs_on_thunk+0x3a/0x3f
 [<ffffffff8100caba>] ? child_rip+0xa/0x20
 [<ffffffff8100c4bc>] ? restore_args+0x0/0x30
 [<ffffffff812dd32f>] ? schedule+0x9/0x1d
 [<ffffffff8104dec6>] ? kthreadd+0xff/0x124
 [<ffffffff8104deeb>] ? kthread+0x0/0x80
 [<ffffffff8100cab0>] ? child_rip+0x0/0x20
---[ end trace 7f81e8c4c224b5ed ]---
Rx BA session stop requested for 00:21:a0:10:17:b0 tid 0
iwlagn 0000:01:00.0: Invalid station for AGG tid 0
HW problem - can not stop rx aggregation for tid 0
phy6: Removed STA 00:21:a0:10:17:b0
phy6: Destroyed STA 00:21:a0:10:17:b0
wlan0: direct probe to AP 00:21:a0:10:17:b0 try 1
wlan0 direct probe responded
wlan0: authenticate with AP 00:21:a0:10:17:b0
wlan0: authenticated
wlan0: associate with AP 00:21:a0:10:17:b0
wlan0: RX ReassocResp from 00:21:a0:10:17:b0 (capab=0x421 status=0 aid=1)
wlan0: associated
phy6: Allocated STA 00:21:a0:10:17:b0
phy6: Inserted STA 00:21:a0:10:17:b0
wlan0: CTS protection enabled (BSSID=00:21:a0:10:17:b0)
wlan0: switched to short barker preamble (BSSID=00:21:a0:10:17:b0)
wlan0: switched to short slot time (BSSID=00:21:a0:10:17:b0)
Rx A-MPDU request on tid 0 result 0
wlan0: deauthenticated (Reason: 2)
Rx BA session stop requested for 00:21:a0:10:17:b0 tid 0
iwlagn 0000:01:00.0: Invalid station for AGG tid 0
HW problem - can not stop rx aggregation for tid 0
phy6: Removed STA 00:21:a0:10:17:b0
phy6: Destroyed STA 00:21:a0:10:17:b0
wlan0: direct probe to AP 00:21:a0:10:17:b0 try 1
wlan0 direct probe responded
wlan0: authenticate with AP 00:21:a0:10:17:b0
wlan0: authenticated
wlan0: associate with AP 00:21:a0:10:17:b0
wlan0: RX ReassocResp from 00:21:a0:10:17:b0 (capab=0x421 status=0 aid=1)
wlan0: associated
phy6: Allocated STA 00:21:a0:10:17:b0
phy6: Inserted STA 00:21:a0:10:17:b0
wlan0: CTS protection enabled (BSSID=00:21:a0:10:17:b0)
wlan0: switched to short barker preamble (BSSID=00:21:a0:10:17:b0)
wlan0: switched to short slot time (BSSID=00:21:a0:10:17:b0)
Rx A-MPDU request on tid 0 result 0
wlan0: deauthenticated (Reason: 2)
Rx BA session stop requested for 00:21:a0:10:17:b0 tid 0
iwlagn 0000:01:00.0: Invalid station for AGG tid 0
HW problem - can not stop rx aggregation for tid 0
phy6: Removed STA 00:21:a0:10:17:b0
phy6: Destroyed STA 00:21:a0:10:17:b0
wlan0: direct probe to AP 00:21:a0:10:17:b0 try 1
wlan0: direct probe to AP 00:21:a0:10:17:b0 try 2
wlan0: direct probe to AP 00:21:a0:10:17:b0 try 3
wlan0: direct probe to AP 00:21:a0:10:17:b0 timed out
phy6: device now idle