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- From: Tobias Klausmann <tobias.johannes.klausmann@mni.thm.de>
- Date: Mon, 12 Dec 2016 19:50:01 +0100
- Subject: [PATCH] ath9k: unlock rcu read when returning early
- 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 <tobias.johannes.klausmann@mni.thm.de>
- Signed-off-by: Felix Fietkau <nbd@nbd.name>
- ---
- --- a/drivers/net/wireless/ath/ath9k/xmit.c
- +++ b/drivers/net/wireless/ath/ath9k/xmit.c
- @@ -2757,7 +2757,7 @@ void ath_tx_edma_tasklet(struct ath_soft
- 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);
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