Starting with ath9k: use ieee80211_tx_status_noskb where possible
[d94a461d7a7df68991fb9663531173f60ef89c68] the driver uses rcu_read_lock() &&
rcu_read_unlock() yet on returning early in ath_tx_edma_tasklet() the unlock is
missing leading to stalls and suspicious RCU usage:
===============================
[ INFO: suspicious RCU usage. ]
4.9.0-rc8 #11 Not tainted
-------------------------------
kernel/rcu/tree.c:705 Illegal idle entry in RCU read-side critical section.!
other info that might help us debug this:
RCU used illegally from idle CPU!
rcu_scheduler_active = 1, debug_locks = 0
RCU used illegally from extended quiescent state!
1 lock held by swapper/7/0:
#0:
(
rcu_read_lock
){......}
, at:
[<ffffffffa06ed110>] ath_tx_edma_tasklet+0x0/0x450 [ath9k]
stack backtrace:
CPU: 7 PID: 0 Comm: swapper/7 Not tainted 4.9.0-rc8 #11
Hardware name: Acer Aspire V3-571G/VA50_HC_CR, BIOS V2.21 12/16/2013
ffff88025efc3f38 ffffffff8132b1e5 ffff88017ede4540 0000000000000001
ffff88025efc3f68 ffffffff810a25f7 ffff88025efcee60 ffff88017edebdd8
ffff88025eeb5400 0000000000000091 ffff88025efc3f88 ffffffff810c3cd4
Call Trace:
<IRQ>
[<ffffffff8132b1e5>] dump_stack+0x68/0x93
[<ffffffff810a25f7>] lockdep_rcu_suspicious+0xd7/0x110
[<ffffffff810c3cd4>] rcu_eqs_enter_common.constprop.85+0x154/0x200
[<ffffffff810c5a54>] rcu_irq_exit+0x44/0xa0
[<ffffffff81058631>] irq_exit+0x61/0xd0
[<ffffffff81018d25>] do_IRQ+0x65/0x110
[<ffffffff81672189>] common_interrupt+0x89/0x89
<EOI>
[<ffffffff814ffe11>] ? cpuidle_enter_state+0x151/0x200
[<ffffffff814ffee2>] cpuidle_enter+0x12/0x20
[<ffffffff8109a6ae>] call_cpuidle+0x1e/0x40
[<ffffffff8109a8f6>] cpu_startup_entry+0x146/0x220
[<ffffffff810336f8>] start_secondary+0x148/0x170
Signed-off-by: Tobias Klausmann <[email protected]>
---
drivers/net/wireless/ath/ath9k/xmit.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/net/wireless/ath/ath9k/xmit.c b/drivers/net/wireless/ath/ath9k/xmit.c
index 52bfbb988611..857d5ae09a1d 100644
--- a/drivers/net/wireless/ath/ath9k/xmit.c
+++ b/drivers/net/wireless/ath/ath9k/xmit.c
@@ -2787,6 +2787,7 @@ void ath_tx_edma_tasklet(struct ath_softc *sc)
fifo_list = &txq->txq_fifo[txq->txq_tailidx];
if (list_empty(fifo_list)) {
ath_txq_unlock(sc, txq);
+ rcu_read_unlock();
return;
}
--
2.11.0
Tobias Klausmann <[email protected]> writes:
> Starting with ath9k: use ieee80211_tx_status_noskb where possible
> [d94a461d7a7df68991fb9663531173f60ef89c68]
The correct format to reference a commit in the commit log is:
Starting with commit d94a461d7a7d ("ath9k: use ieee80211_tx_status_noskb
where possible") the...
> the driver uses rcu_read_lock() && rcu_read_unlock() yet on returning
> early in ath_tx_edma_tasklet() the unlock is missing leading to stalls
> and suspicious RCU usage:
>
> ===============================
> [ INFO: suspicious RCU usage. ]
> 4.9.0-rc8 #11 Not tainted
> -------------------------------
> kernel/rcu/tree.c:705 Illegal idle entry in RCU read-side critical section.!
>
> other info that might help us debug this:
>
> RCU used illegally from idle CPU!
> rcu_scheduler_active = 1, debug_locks = 0
> RCU used illegally from extended quiescent state!
> 1 lock held by swapper/7/0:
> #0:
> (
> rcu_read_lock
> ){......}
> , at:
> [<ffffffffa06ed110>] ath_tx_edma_tasklet+0x0/0x450 [ath9k]
>
> stack backtrace:
> CPU: 7 PID: 0 Comm: swapper/7 Not tainted 4.9.0-rc8 #11
> Hardware name: Acer Aspire V3-571G/VA50_HC_CR, BIOS V2.21 12/16/2013
> ffff88025efc3f38 ffffffff8132b1e5 ffff88017ede4540 0000000000000001
> ffff88025efc3f68 ffffffff810a25f7 ffff88025efcee60 ffff88017edebdd8
> ffff88025eeb5400 0000000000000091 ffff88025efc3f88 ffffffff810c3cd4
> Call Trace:
> <IRQ>
> [<ffffffff8132b1e5>] dump_stack+0x68/0x93
> [<ffffffff810a25f7>] lockdep_rcu_suspicious+0xd7/0x110
> [<ffffffff810c3cd4>] rcu_eqs_enter_common.constprop.85+0x154/0x200
> [<ffffffff810c5a54>] rcu_irq_exit+0x44/0xa0
> [<ffffffff81058631>] irq_exit+0x61/0xd0
> [<ffffffff81018d25>] do_IRQ+0x65/0x110
> [<ffffffff81672189>] common_interrupt+0x89/0x89
> <EOI>
> [<ffffffff814ffe11>] ? cpuidle_enter_state+0x151/0x200
> [<ffffffff814ffee2>] cpuidle_enter+0x12/0x20
> [<ffffffff8109a6ae>] call_cpuidle+0x1e/0x40
> [<ffffffff8109a8f6>] cpu_startup_entry+0x146/0x220
> [<ffffffff810336f8>] start_secondary+0x148/0x170
>
> Signed-off-by: Tobias Klausmann <[email protected]>
A fixes line and cc stable would be good to have:
Fixes: d94a461d7a7d ("ath9k: use ieee80211_tx_status_noskb where possible")
Cc: <[email protected]> # v4.9
I can add those.
I'm planning to push this to 4.10 but would prefer to see an ack from
Felix (the author of d94a461d7a7d) first. I added him to Cc.
--
Kalle Valo
On 2016-12-12 19:50, Tobias Klausmann wrote:
> Starting with ath9k: use ieee80211_tx_status_noskb where possible
> [d94a461d7a7df68991fb9663531173f60ef89c68] the driver uses rcu_read_lock() &&
> rcu_read_unlock() yet on returning early in ath_tx_edma_tasklet() the unlock is
> missing leading to stalls and suspicious RCU usage:
>
> ===============================
> [ INFO: suspicious RCU usage. ]
> 4.9.0-rc8 #11 Not tainted
> -------------------------------
> kernel/rcu/tree.c:705 Illegal idle entry in RCU read-side critical section.!
>
> other info that might help us debug this:
>
> RCU used illegally from idle CPU!
> rcu_scheduler_active = 1, debug_locks = 0
> RCU used illegally from extended quiescent state!
> 1 lock held by swapper/7/0:
> #0:
> (
> rcu_read_lock
> ){......}
> , at:
> [<ffffffffa06ed110>] ath_tx_edma_tasklet+0x0/0x450 [ath9k]
>
> stack backtrace:
> CPU: 7 PID: 0 Comm: swapper/7 Not tainted 4.9.0-rc8 #11
> Hardware name: Acer Aspire V3-571G/VA50_HC_CR, BIOS V2.21 12/16/2013
> ffff88025efc3f38 ffffffff8132b1e5 ffff88017ede4540 0000000000000001
> ffff88025efc3f68 ffffffff810a25f7 ffff88025efcee60 ffff88017edebdd8
> ffff88025eeb5400 0000000000000091 ffff88025efc3f88 ffffffff810c3cd4
> Call Trace:
> <IRQ>
> [<ffffffff8132b1e5>] dump_stack+0x68/0x93
> [<ffffffff810a25f7>] lockdep_rcu_suspicious+0xd7/0x110
> [<ffffffff810c3cd4>] rcu_eqs_enter_common.constprop.85+0x154/0x200
> [<ffffffff810c5a54>] rcu_irq_exit+0x44/0xa0
> [<ffffffff81058631>] irq_exit+0x61/0xd0
> [<ffffffff81018d25>] do_IRQ+0x65/0x110
> [<ffffffff81672189>] common_interrupt+0x89/0x89
> <EOI>
> [<ffffffff814ffe11>] ? cpuidle_enter_state+0x151/0x200
> [<ffffffff814ffee2>] cpuidle_enter+0x12/0x20
> [<ffffffff8109a6ae>] call_cpuidle+0x1e/0x40
> [<ffffffff8109a8f6>] cpu_startup_entry+0x146/0x220
> [<ffffffff810336f8>] start_secondary+0x148/0x170
>
> Signed-off-by: Tobias Klausmann <[email protected]>
> ---
> drivers/net/wireless/ath/ath9k/xmit.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/net/wireless/ath/ath9k/xmit.c b/drivers/net/wireless/ath/ath9k/xmit.c
> index 52bfbb988611..857d5ae09a1d 100644
> --- a/drivers/net/wireless/ath/ath9k/xmit.c
> +++ b/drivers/net/wireless/ath/ath9k/xmit.c
> @@ -2787,6 +2787,7 @@ void ath_tx_edma_tasklet(struct ath_softc *sc)
> fifo_list = &txq->txq_fifo[txq->txq_tailidx];
> if (list_empty(fifo_list)) {
> ath_txq_unlock(sc, txq);
> + rcu_read_unlock();
Technically this is fine as well, but I'd prefer a fix where you replace
the 'return' with 'break', thus avoiding the duplication of
rcu_read_unlock()
Thanks,
- Felix
On 13.12.2016 11:41, Felix Fietkau wrote:
> On 2016-12-12 19:50, Tobias Klausmann wrote:
>> Starting with ath9k: use ieee80211_tx_status_noskb where possible
>> [d94a461d7a7df68991fb9663531173f60ef89c68] the driver uses rcu_read_lock() &&
>> rcu_read_unlock() yet on returning early in ath_tx_edma_tasklet() the unlock is
>> missing leading to stalls and suspicious RCU usage:
>>
>> ===============================
>> [ INFO: suspicious RCU usage. ]
>> 4.9.0-rc8 #11 Not tainted
>> -------------------------------
>> kernel/rcu/tree.c:705 Illegal idle entry in RCU read-side critical section.!
>>
>> other info that might help us debug this:
>>
>> RCU used illegally from idle CPU!
>> rcu_scheduler_active = 1, debug_locks = 0
>> RCU used illegally from extended quiescent state!
>> 1 lock held by swapper/7/0:
>> #0:
>> (
>> rcu_read_lock
>> ){......}
>> , at:
>> [<ffffffffa06ed110>] ath_tx_edma_tasklet+0x0/0x450 [ath9k]
>>
>> stack backtrace:
>> CPU: 7 PID: 0 Comm: swapper/7 Not tainted 4.9.0-rc8 #11
>> Hardware name: Acer Aspire V3-571G/VA50_HC_CR, BIOS V2.21 12/16/2013
>> ffff88025efc3f38 ffffffff8132b1e5 ffff88017ede4540 0000000000000001
>> ffff88025efc3f68 ffffffff810a25f7 ffff88025efcee60 ffff88017edebdd8
>> ffff88025eeb5400 0000000000000091 ffff88025efc3f88 ffffffff810c3cd4
>> Call Trace:
>> <IRQ>
>> [<ffffffff8132b1e5>] dump_stack+0x68/0x93
>> [<ffffffff810a25f7>] lockdep_rcu_suspicious+0xd7/0x110
>> [<ffffffff810c3cd4>] rcu_eqs_enter_common.constprop.85+0x154/0x200
>> [<ffffffff810c5a54>] rcu_irq_exit+0x44/0xa0
>> [<ffffffff81058631>] irq_exit+0x61/0xd0
>> [<ffffffff81018d25>] do_IRQ+0x65/0x110
>> [<ffffffff81672189>] common_interrupt+0x89/0x89
>> <EOI>
>> [<ffffffff814ffe11>] ? cpuidle_enter_state+0x151/0x200
>> [<ffffffff814ffee2>] cpuidle_enter+0x12/0x20
>> [<ffffffff8109a6ae>] call_cpuidle+0x1e/0x40
>> [<ffffffff8109a8f6>] cpu_startup_entry+0x146/0x220
>> [<ffffffff810336f8>] start_secondary+0x148/0x170
>>
>> Signed-off-by: Tobias Klausmann <[email protected]>
>> ---
>> drivers/net/wireless/ath/ath9k/xmit.c | 1 +
>> 1 file changed, 1 insertion(+)
>>
>> diff --git a/drivers/net/wireless/ath/ath9k/xmit.c b/drivers/net/wireless/ath/ath9k/xmit.c
>> index 52bfbb988611..857d5ae09a1d 100644
>> --- a/drivers/net/wireless/ath/ath9k/xmit.c
>> +++ b/drivers/net/wireless/ath/ath9k/xmit.c
>> @@ -2787,6 +2787,7 @@ void ath_tx_edma_tasklet(struct ath_softc *sc)
>> fifo_list = &txq->txq_fifo[txq->txq_tailidx];
>> if (list_empty(fifo_list)) {
>> ath_txq_unlock(sc, txq);
>> + rcu_read_unlock();
> Technically this is fine as well, but I'd prefer a fix where you replace
> the 'return' with 'break', thus avoiding the duplication of
> rcu_read_unlock()
Actually if you want to avoid it, maybe skipping over the rest is better
(as originally intended):
...
ath_txq_unlock(sc, txq);
goto unlock;
}
...
unlock:
rcu_read_unlock();
Thanks,
Tobias
>
> Thanks,
>
> - Felix
>
On 2016-12-13 14:41, Tobias Klausmann wrote:
> On 13.12.2016 11:41, Felix Fietkau wrote:
>> On 2016-12-12 19:50, Tobias Klausmann wrote:
>>> diff --git a/drivers/net/wireless/ath/ath9k/xmit.c b/drivers/net/wireless/ath/ath9k/xmit.c
>>> index 52bfbb988611..857d5ae09a1d 100644
>>> --- a/drivers/net/wireless/ath/ath9k/xmit.c
>>> +++ b/drivers/net/wireless/ath/ath9k/xmit.c
>>> @@ -2787,6 +2787,7 @@ void ath_tx_edma_tasklet(struct ath_softc *sc)
>>> fifo_list = &txq->txq_fifo[txq->txq_tailidx];
>>> if (list_empty(fifo_list)) {
>>> ath_txq_unlock(sc, txq);
>>> + rcu_read_unlock();
>> Technically this is fine as well, but I'd prefer a fix where you replace
>> the 'return' with 'break', thus avoiding the duplication of
>> rcu_read_unlock()
>
> Actually if you want to avoid it, maybe skipping over the rest is better
> (as originally intended):
>
> ...
>
> ath_txq_unlock(sc, txq);
>
>
> goto unlock;
> }
> ...
>
> unlock:
> rcu_read_unlock();
There are already other places that skip to the rcu_read_unlock() part
by using 'break'. I don't see how adding an unnecessary goto makes
things any better.
- Felix
Starting with commit d94a461d7a7d ("ath9k: use ieee80211_tx_status_noskb
where possible") the driver uses rcu_read_lock() && rcu_read_unlock(), yet on
returning early in ath_tx_edma_tasklet() the unlock is missing leading to stalls
and suspicious RCU usage:
===============================
[ INFO: suspicious RCU usage. ]
4.9.0-rc8 #11 Not tainted
-------------------------------
kernel/rcu/tree.c:705 Illegal idle entry in RCU read-side critical section.!
other info that might help us debug this:
RCU used illegally from idle CPU!
rcu_scheduler_active = 1, debug_locks = 0
RCU used illegally from extended quiescent state!
1 lock held by swapper/7/0:
#0:
(
rcu_read_lock
){......}
, at:
[<ffffffffa06ed110>] ath_tx_edma_tasklet+0x0/0x450 [ath9k]
stack backtrace:
CPU: 7 PID: 0 Comm: swapper/7 Not tainted 4.9.0-rc8 #11
Hardware name: Acer Aspire V3-571G/VA50_HC_CR, BIOS V2.21 12/16/2013
ffff88025efc3f38 ffffffff8132b1e5 ffff88017ede4540 0000000000000001
ffff88025efc3f68 ffffffff810a25f7 ffff88025efcee60 ffff88017edebdd8
ffff88025eeb5400 0000000000000091 ffff88025efc3f88 ffffffff810c3cd4
Call Trace:
<IRQ>
[<ffffffff8132b1e5>] dump_stack+0x68/0x93
[<ffffffff810a25f7>] lockdep_rcu_suspicious+0xd7/0x110
[<ffffffff810c3cd4>] rcu_eqs_enter_common.constprop.85+0x154/0x200
[<ffffffff810c5a54>] rcu_irq_exit+0x44/0xa0
[<ffffffff81058631>] irq_exit+0x61/0xd0
[<ffffffff81018d25>] do_IRQ+0x65/0x110
[<ffffffff81672189>] common_interrupt+0x89/0x89
<EOI>
[<ffffffff814ffe11>] ? cpuidle_enter_state+0x151/0x200
[<ffffffff814ffee2>] cpuidle_enter+0x12/0x20
[<ffffffff8109a6ae>] call_cpuidle+0x1e/0x40
[<ffffffff8109a8f6>] cpu_startup_entry+0x146/0x220
[<ffffffff810336f8>] start_secondary+0x148/0x170
Signed-off-by: Tobias Klausmann <[email protected]>
Fixes: d94a461d7a7d ("ath9k: use ieee80211_tx_status_noskb where possible")
Cc: <[email protected]> # v4.9
---
v2: break instead of unlock (rename patch) [Felix Fietkau],
fix reference to commit [Kalle Valo]
---
drivers/net/wireless/ath/ath9k/xmit.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/net/wireless/ath/ath9k/xmit.c b/drivers/net/wireless/ath/ath9k/xmit.c
index 52bfbb988611..e47286bf378e 100644
--- a/drivers/net/wireless/ath/ath9k/xmit.c
+++ b/drivers/net/wireless/ath/ath9k/xmit.c
@@ -2787,7 +2787,7 @@ void ath_tx_edma_tasklet(struct ath_softc *sc)
fifo_list = &txq->txq_fifo[txq->txq_tailidx];
if (list_empty(fifo_list)) {
ath_txq_unlock(sc, txq);
- return;
+ break;
}
bf = list_first_entry(fifo_list, struct ath_buf, list);
--
2.11.0
On 2016-12-13 18:08, Tobias Klausmann wrote:
> Starting with commit d94a461d7a7d ("ath9k: use ieee80211_tx_status_noskb
> where possible") the driver uses rcu_read_lock() && rcu_read_unlock(), yet on
> returning early in ath_tx_edma_tasklet() the unlock is missing leading to stalls
> and suspicious RCU usage:
>
> ===============================
> [ INFO: suspicious RCU usage. ]
> 4.9.0-rc8 #11 Not tainted
> -------------------------------
> kernel/rcu/tree.c:705 Illegal idle entry in RCU read-side critical section.!
>
> other info that might help us debug this:
>
> RCU used illegally from idle CPU!
> rcu_scheduler_active = 1, debug_locks = 0
> RCU used illegally from extended quiescent state!
> 1 lock held by swapper/7/0:
> #0:
> (
> rcu_read_lock
> ){......}
> , at:
> [<ffffffffa06ed110>] ath_tx_edma_tasklet+0x0/0x450 [ath9k]
>
> stack backtrace:
> CPU: 7 PID: 0 Comm: swapper/7 Not tainted 4.9.0-rc8 #11
> Hardware name: Acer Aspire V3-571G/VA50_HC_CR, BIOS V2.21 12/16/2013
> ffff88025efc3f38 ffffffff8132b1e5 ffff88017ede4540 0000000000000001
> ffff88025efc3f68 ffffffff810a25f7 ffff88025efcee60 ffff88017edebdd8
> ffff88025eeb5400 0000000000000091 ffff88025efc3f88 ffffffff810c3cd4
> Call Trace:
> <IRQ>
> [<ffffffff8132b1e5>] dump_stack+0x68/0x93
> [<ffffffff810a25f7>] lockdep_rcu_suspicious+0xd7/0x110
> [<ffffffff810c3cd4>] rcu_eqs_enter_common.constprop.85+0x154/0x200
> [<ffffffff810c5a54>] rcu_irq_exit+0x44/0xa0
> [<ffffffff81058631>] irq_exit+0x61/0xd0
> [<ffffffff81018d25>] do_IRQ+0x65/0x110
> [<ffffffff81672189>] common_interrupt+0x89/0x89
> <EOI>
> [<ffffffff814ffe11>] ? cpuidle_enter_state+0x151/0x200
> [<ffffffff814ffee2>] cpuidle_enter+0x12/0x20
> [<ffffffff8109a6ae>] call_cpuidle+0x1e/0x40
> [<ffffffff8109a8f6>] cpu_startup_entry+0x146/0x220
> [<ffffffff810336f8>] start_secondary+0x148/0x170
>
> Signed-off-by: Tobias Klausmann <[email protected]>
> Fixes: d94a461d7a7d ("ath9k: use ieee80211_tx_status_noskb where possible")
> Cc: <[email protected]> # v4.9
Acked-by: Felix Fietkau <[email protected]>
Tobias Klausmann <[email protected]> wrote:
> Starting with commit d94a461d7a7d ("ath9k: use ieee80211_tx_status_noskb
> where possible") the driver uses rcu_read_lock() && rcu_read_unlock(), yet on
> returning early in ath_tx_edma_tasklet() the unlock is missing leading to stalls
> and suspicious RCU usage:
>
> ===============================
> [ INFO: suspicious RCU usage. ]
> 4.9.0-rc8 #11 Not tainted
> -------------------------------
> kernel/rcu/tree.c:705 Illegal idle entry in RCU read-side critical section.!
>
> other info that might help us debug this:
>
> RCU used illegally from idle CPU!
> rcu_scheduler_active = 1, debug_locks = 0
> RCU used illegally from extended quiescent state!
> 1 lock held by swapper/7/0:
> #0:
> (
> rcu_read_lock
> ){......}
> , at:
> [<ffffffffa06ed110>] ath_tx_edma_tasklet+0x0/0x450 [ath9k]
>
> stack backtrace:
> CPU: 7 PID: 0 Comm: swapper/7 Not tainted 4.9.0-rc8 #11
> Hardware name: Acer Aspire V3-571G/VA50_HC_CR, BIOS V2.21 12/16/2013
> ffff88025efc3f38 ffffffff8132b1e5 ffff88017ede4540 0000000000000001
> ffff88025efc3f68 ffffffff810a25f7 ffff88025efcee60 ffff88017edebdd8
> ffff88025eeb5400 0000000000000091 ffff88025efc3f88 ffffffff810c3cd4
> Call Trace:
> <IRQ>
> [<ffffffff8132b1e5>] dump_stack+0x68/0x93
> [<ffffffff810a25f7>] lockdep_rcu_suspicious+0xd7/0x110
> [<ffffffff810c3cd4>] rcu_eqs_enter_common.constprop.85+0x154/0x200
> [<ffffffff810c5a54>] rcu_irq_exit+0x44/0xa0
> [<ffffffff81058631>] irq_exit+0x61/0xd0
> [<ffffffff81018d25>] do_IRQ+0x65/0x110
> [<ffffffff81672189>] common_interrupt+0x89/0x89
> <EOI>
> [<ffffffff814ffe11>] ? cpuidle_enter_state+0x151/0x200
> [<ffffffff814ffee2>] cpuidle_enter+0x12/0x20
> [<ffffffff8109a6ae>] call_cpuidle+0x1e/0x40
> [<ffffffff8109a8f6>] cpu_startup_entry+0x146/0x220
> [<ffffffff810336f8>] start_secondary+0x148/0x170
>
> Signed-off-by: Tobias Klausmann <[email protected]>
> Fixes: d94a461d7a7d ("ath9k: use ieee80211_tx_status_noskb where possible")
> Cc: <[email protected]> # v4.9
> Acked-by: Felix Fietkau <[email protected]>
Patch applied to ath-current branch of ath.git, thanks.
d1f1c0e289e1 ath9k: do not return early to fix rcu unlocking
--
https://patchwork.kernel.org/patch/9472709/
Documentation about submitting wireless patches and checking status
from patchwork:
https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches