From: Kalle Valo <kvalo@codeaurora.org>
To: Tobias Klausmann <tobias.johannes.klausmann@mni.thm.de>
Cc: helgaas@kernel.org, linux-kernel@vger.kernel.org,
linux-pci@vger.kernel.org, marc.zyngier@arm.com,
Janusz.Dziedzic@tieto.com, rmanohar@qti.qualcomm.com,
ath9k-devel@qca.qualcomm.com, linux-wireless@vger.kernel.org,
rmanohar@qca.qualcomm.com, bharat.kumar.gogada@xilinx.com,
Felix Fietkau <nbd@nbd.name>
Subject: Re: [PATCH] ath9k: unlock rcu read when returning early
Date: Tue, 13 Dec 2016 11:59:42 +0200 [thread overview]
Message-ID: <877f74175d.fsf@kamboji.qca.qualcomm.com> (raw)
In-Reply-To: <20161212185001.3857-1-tobias.johannes.klausmann@mni.thm.de> (Tobias Klausmann's message of "Mon, 12 Dec 2016 19:50:01 +0100")
Tobias Klausmann <tobias.johannes.klausmann@mni.thm.de> 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 <tobias.johannes.klausmann@mni.thm.de>
A fixes line and cc stable would be good to have:
Fixes: d94a461d7a7d ("ath9k: use ieee80211_tx_status_noskb where possible")
Cc: <stable@vger.kernel.org> # 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
next prev parent reply other threads:[~2016-12-13 9:59 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1cFMHb-00BdWd-Ks>
2016-12-12 18:50 ` [PATCH] ath9k: unlock rcu read when returning early Tobias Klausmann
2016-12-13 9:59 ` Kalle Valo [this message]
2016-12-13 10:41 ` Felix Fietkau
2016-12-13 13:41 ` Tobias Klausmann
2016-12-13 13:52 ` Felix Fietkau
2016-12-13 17:08 ` [PATCH v2] ath9k: do not return early to fix rcu unlocking Tobias Klausmann
2016-12-14 20:45 ` Felix Fietkau
2016-12-21 14:29 ` [v2] " Kalle Valo
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