On 10/15/2010 04:21 PM, Luis R. Rodriguez wrote:
Ben, please give this patch a shot. I addresses three races on the PCU:
* When we were stopping the CPU for non-EDMA cards we never locked against
anything starting the PCU again
* ath9k_hw_startpcureceive() was being called without locking
* Although we lock on the rxbuf lock for contention against starting/stopping
the PCU, we also need to lock on the driver in locations where we start/stop
the PCU within the same location otherwise we end up in inconsistant states
and the hardware may end up proessing an incorrect buffer for DMA. To
protect against this we use a new PCU lock on the main part of the driver to
ensure each start/stop/reset operation is done atomically.
And fixes one issue as a side effect:
* No more packet loss on ping flood when you have one STA associated :)
The only issue I see with this is I eventually run out of memory and my box
becomes useless, unless I am mistaking that for some other issue.
Please give this a shot and if it cures your woes I'll split it up into
3 separate patches, or maybe just two, one for the first two and one for
the last issue.
Sounds good, but this lockdep splat happens almost immediately upon starting
my app:
=======================================================
[ INFO: possible circular locking dependency detected ]
2.6.36-rc8-wl+ #32
-------------------------------------------------------
swapper/0 is trying to acquire lock:
(&(&sc->rx.pcu_lock)->rlock){+.-...}, at: [<fa16e5c7>] ath9k_tasklet+0x7e/0x140 [ath9k]
but task is already holding lock:
(&(&sc->rx.rxflushlock)->rlock){+.-...}, at: [<fa16e5b9>] ath9k_tasklet+0x70/0x140 [ath9k]
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (&(&sc->rx.rxflushlock)->rlock){+.-...}:
[<c0457639>] lock_acquire+0x5a/0x78
[<c075f6ed>] _raw_spin_lock_bh+0x20/0x2f
[<fa170513>] ath_flushrecv+0x14/0x61 [ath9k]
[<fa16dda2>] ath_radio_disable+0x83/0x143 [ath9k]
[<fa16e370>] ath9k_config+0x3c3/0x3d8 [ath9k]
[<fa09ca2e>] ieee80211_hw_config+0x11b/0x125 [mac80211]
[<fa0a8edf>] ieee80211_do_open+0x3c5/0x466 [mac80211]
[<fa0a8fdb>] ieee80211_open+0x5b/0x5e [mac80211]
[<c06ce76b>] __dev_open+0x80/0xae
[<c06cc99b>] __dev_change_flags+0xa0/0x115
[<c06ce6bf>] dev_change_flags+0x13/0x3f
[<c06d7e78>] do_setlink+0x23a/0x51b
[<c06d847c>] rtnl_newlink+0x269/0x431
[<c06d79e2>] rtnetlink_rcv_msg+0x182/0x198
[<c06e503c>] netlink_rcv_skb+0x30/0x77
[<c06d7859>] rtnetlink_rcv+0x1b/0x22
[<c06e4e77>] netlink_unicast+0xbe/0x119
[<c06e5a15>] netlink_sendmsg+0x234/0x24c
[<c06bf93a>] __sock_sendmsg+0x51/0x5a
[<c06bfba4>] sock_sendmsg+0x93/0xa7
[<c06bfd8c>] sys_sendmsg+0x149/0x193
[<c06c148b>] sys_socketcall+0x15e/0x1a5
[<c0402f1c>] sysenter_do_call+0x12/0x38
-> #0 (&(&sc->rx.pcu_lock)->rlock){+.-...}:
[<c0457374>] __lock_acquire+0x921/0xb8c
[<c0457639>] lock_acquire+0x5a/0x78
[<c075f6ed>] _raw_spin_lock_bh+0x20/0x2f
[<fa16e5c7>] ath9k_tasklet+0x7e/0x140 [ath9k]
[<c0438fd1>] tasklet_action+0x73/0xc6
[<c043945f>] __do_softirq+0x86/0x111
[<c0439520>] do_softirq+0x36/0x5a
[<c0439659>] irq_exit+0x35/0x69
[<c0403fb9>] do_IRQ+0x86/0x9a
[<c04034ee>] common_interrupt+0x2e/0x40
[<c040227f>] cpu_idle+0x4e/0x6b
[<c074b6e9>] rest_init+0x8d/0x92
[<c09758ea>] start_kernel+0x320/0x325
[<c09750d0>] i386_start_kernel+0xd0/0xd7
other info that might help us debug this:
1 lock held by swapper/0:
#0: (&(&sc->rx.rxflushlock)->rlock){+.-...}, at: [<fa16e5b9>] ath9k_tasklet+0x70/0x140 [ath9k]
stack backtrace:
Pid: 0, comm: swapper Not tainted 2.6.36-rc8-wl+ #32
Call Trace:
[<c075d940>] ? printk+0xf/0x17
[<c04565af>] print_circular_bug+0x91/0x9d
[<c0457374>] __lock_acquire+0x921/0xb8c
[<c0457639>] lock_acquire+0x5a/0x78
[<fa16e5c7>] ? ath9k_tasklet+0x7e/0x140 [ath9k]
[<c075f6ed>] _raw_spin_lock_bh+0x20/0x2f
[<fa16e5c7>] ? ath9k_tasklet+0x7e/0x140 [ath9k]
[<fa16e5c7>] ath9k_tasklet+0x7e/0x140 [ath9k]
[<c0438fd1>] tasklet_action+0x73/0xc6
[<c043945f>] __do_softirq+0x86/0x111
[<c0439520>] do_softirq+0x36/0x5a
[<c0439659>] irq_exit+0x35/0x69
[<c0403fb9>] do_IRQ+0x86/0x9a
[<c04034ee>] common_interrupt+0x2e/0x40
[<c045007b>] ? do_adjtimex+0x223/0x55e
[<c0408245>] ? mwait_idle+0x5c/0x6c
[<c040227f>] cpu_idle+0x4e/0x6b
[<c074b6e9>] rest_init+0x8d/0x92
[<c09758ea>] start_kernel+0x320/0x325
[<c09750d0>] i386_start_kernel+0xd0/0xd7
--
Ben Greear <greearb@xxxxxxxxxxxxxxx>
Candela Technologies Inc http://www.candelatech.com
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