Re: [PATCH v2] ath9k: do not return early to fix rcu unlocking
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:
> [] 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
> 88025efc3f38 8132b1e5 88017ede4540 0001
> 88025efc3f68 810a25f7 88025efcee60 88017edebdd8
> 88025eeb5400 0091 88025efc3f88 810c3cd4
> Call Trace:
>
> [] dump_stack+0x68/0x93
> [] lockdep_rcu_suspicious+0xd7/0x110
> [] rcu_eqs_enter_common.constprop.85+0x154/0x200
> [] rcu_irq_exit+0x44/0xa0
> [] irq_exit+0x61/0xd0
> [] do_IRQ+0x65/0x110
> [] common_interrupt+0x89/0x89
>
> [] ? cpuidle_enter_state+0x151/0x200
> [] cpuidle_enter+0x12/0x20
> [] call_cpuidle+0x1e/0x40
> [] cpu_startup_entry+0x146/0x220
> [] start_secondary+0x148/0x170
>
> Signed-off-by: Tobias Klausmann
> Fixes: d94a461d7a7d ("ath9k: use ieee80211_tx_status_noskb where possible")
> Cc: # v4.9
Acked-by: Felix Fietkau
Re: [PATCH v2] ath9k: do not return early to fix rcu unlocking
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:
> [] 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
> 88025efc3f38 8132b1e5 88017ede4540 0001
> 88025efc3f68 810a25f7 88025efcee60 88017edebdd8
> 88025eeb5400 0091 88025efc3f88 810c3cd4
> Call Trace:
>
> [] dump_stack+0x68/0x93
> [] lockdep_rcu_suspicious+0xd7/0x110
> [] rcu_eqs_enter_common.constprop.85+0x154/0x200
> [] rcu_irq_exit+0x44/0xa0
> [] irq_exit+0x61/0xd0
> [] do_IRQ+0x65/0x110
> [] common_interrupt+0x89/0x89
>
> [] ? cpuidle_enter_state+0x151/0x200
> [] cpuidle_enter+0x12/0x20
> [] call_cpuidle+0x1e/0x40
> [] cpu_startup_entry+0x146/0x220
> [] start_secondary+0x148/0x170
>
> Signed-off-by: Tobias Klausmann
> Fixes: d94a461d7a7d ("ath9k: use ieee80211_tx_status_noskb where possible")
> Cc: # v4.9
Acked-by: Felix Fietkau
[PATCH v2] ath9k: do not return early to fix rcu unlocking
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:
[] 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
88025efc3f38 8132b1e5 88017ede4540 0001
88025efc3f68 810a25f7 88025efcee60 88017edebdd8
88025eeb5400 0091 88025efc3f88 810c3cd4
Call Trace:
[] dump_stack+0x68/0x93
[] lockdep_rcu_suspicious+0xd7/0x110
[] rcu_eqs_enter_common.constprop.85+0x154/0x200
[] rcu_irq_exit+0x44/0xa0
[] irq_exit+0x61/0xd0
[] do_IRQ+0x65/0x110
[] common_interrupt+0x89/0x89
[] ? cpuidle_enter_state+0x151/0x200
[] cpuidle_enter+0x12/0x20
[] call_cpuidle+0x1e/0x40
[] cpu_startup_entry+0x146/0x220
[] start_secondary+0x148/0x170
Signed-off-by: Tobias Klausmann
Fixes: d94a461d7a7d ("ath9k: use ieee80211_tx_status_noskb where possible")
Cc: # 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_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
[PATCH v2] ath9k: do not return early to fix rcu unlocking
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:
[] 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
88025efc3f38 8132b1e5 88017ede4540 0001
88025efc3f68 810a25f7 88025efcee60 88017edebdd8
88025eeb5400 0091 88025efc3f88 810c3cd4
Call Trace:
[] dump_stack+0x68/0x93
[] lockdep_rcu_suspicious+0xd7/0x110
[] rcu_eqs_enter_common.constprop.85+0x154/0x200
[] rcu_irq_exit+0x44/0xa0
[] irq_exit+0x61/0xd0
[] do_IRQ+0x65/0x110
[] common_interrupt+0x89/0x89
[] ? cpuidle_enter_state+0x151/0x200
[] cpuidle_enter+0x12/0x20
[] call_cpuidle+0x1e/0x40
[] cpu_startup_entry+0x146/0x220
[] start_secondary+0x148/0x170
Signed-off-by: Tobias Klausmann
Fixes: d94a461d7a7d ("ath9k: use ieee80211_tx_status_noskb where possible")
Cc: # 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_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
