#1889: AP: iwconfig ath0 channel 05 == deadlock
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Reporter: Andrew Lunn <[EMAIL PROTECTED]> | Type: defect
Status: new | Priority: major
Component: madwifi: other | Version: v0.9.4
Keywords: channel change deadlock | Patch_attached: 0
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I found a deadlock. Linux kernel 2.6.23.9, not that it matters. Madwifi
0.9.4.
{{{
modprobe ath_pci autocreate=ap
iwconfig ath0 essid foobar
ifconfig ath0 up
sleep 10
sync
iwconfig ath0 channel 5
}}}
And you are now deadlocked.
I tracked it down. The stack trace when it deadlocks is:
{{{
[<c0104ebb>] show_trace_log_lvl+0x1a/0x2f
[<c01059ca>] show_trace+0x12/0x14
[<c01059e2>] dump_stack+0x16/0x18
[<f8995270>] ieee80211_free_node+0x20/0x88 [wlan]
[<f8941f34>] ath_tx_draintxq+0x124/0x171 [ath_pci]
[<f89420b4>] ath_draintxq+0x133/0x144 [ath_pci]
[<f8946400>] ath_set_channel+0x17a/0x4de [ath_pci]
[<f898d4b4>] ieee80211_beacon_update+0x26f/0x94f [wlan]
[<f894365c>] ath_beacon_generate+0x339/0x509 [ath_pci]
[<f894c736>] ath_intr+0x2f7/0xb19 [ath_pci]
[<c014cb54>] handle_IRQ_event+0x1a/0x46
[<c014dbfc>] handle_fasteoi_irq+0x7d/0xb6
[<c0106657>] do_IRQ+0x7c/0x95
[<c01048ba>] common_interrupt+0x2e/0x34
[<c010239e>] cpu_idle+0x9c/0xb5
[<c0282585>] rest_init+0x4d/0x4f
[<c035f96d>] start_kernel+0x318/0x320
[<00000000>] 0x0
}}}
ieee80211_beacon_update() locks ic.
ieee80211_free_node() also wants to lock ic, which results in a deadlock.
I think this also means DOTH's channel change in general is broken and not
just when triggered by a user.
--
Ticket URL: <https://madwifi.org/ticket/1889>
madwifi.org <http://madwifi.org/>
Multiband Atheros Driver for Wireless Fidelity
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