Re: [PATCH 1/3] ath10k: Ensure there are no stale ar->txqs entries.

From: Ben Greear <greearb@candelatech.com>
To: Michal Kazior <michal.kazior@tieto.com>
Cc: linux-wireless <linux-wireless@vger.kernel.org>,
	"ath10k@lists.infradead.org" <ath10k@lists.infradead.org>
Subject: Re: [PATCH 1/3] ath10k: Ensure there are no stale ar->txqs entries.
Date: Thu, 1 Dec 2016 14:52:59 -0800	[thread overview]
Message-ID: <ba1cc818-6194-11d6-7cc3-1db28036a519@candelatech.com> (raw)
In-Reply-To: <57B70AED.2010200@candelatech.com>

On 08/19/2016 06:34 AM, Ben Greear wrote:
>
>
> On 08/18/2016 11:59 PM, Michal Kazior wrote:
>> On 19 August 2016 at 03:26,  <greearb@candelatech.com> wrote:
>>> From: Ben Greear <greearb@candelatech.com>
>>>
>>> I was seeing kernel crashes due to accessing freed memory
>>> while debugging a 9984 firmware that was crashing often.
>>>
>>> This patch fixes the crashes.  I am not certain if there
>>> is a better way or not.

I did some more hacking on this today.  I think I found some better clue on this.

I added this code:

static void ath10k_mac_txq_init(struct ath10k *ar, struct ieee80211_txq *txq)
{
	struct ath10k_txq *artxq = (void *)txq->drv_priv;
	struct ath10k_txq *tmp, *walker;
	struct ieee80211_txq *txq_tmp;
	int i = 0;

	if (!txq)
		return;

	spin_lock_bh(&ar->txqs_lock);
	ar->txqs_lock.rlock.dbg1 = 104;

	/* Remove from ar->txqs in case it still exists there. */
	list_for_each_entry_safe(walker, tmp, &ar->txqs, list) {
		txq_tmp = container_of((void *)walker, struct ieee80211_txq,
				       drv_priv);
		if ((++i % 10000) == 0) {
			ath10k_err(ar, "txq-init: Checking txq_tmp: %p i: %d\n", txq_tmp, i);
			ath10k_err(ar, "txq-init: txqs: %p walker->list: %p w->next: %p  w->prev: %p ar->txqs: %p\n",
				   &ar->txqs, &(walker->list), walker->list.next, walker->list.prev, &ar->txqs);
		}

		if (txq_tmp == txq) {
			WARN_ON_ONCE(1);
			ath10k_err(ar, "txq-init: Found txq when it should be deleted, txq_tmp: %p  txq: %p\n",
				   txq_tmp, txq);
			list_del(&walker->list);
		}
	}
	spin_unlock_bh(&ar->txqs_lock);

	INIT_LIST_HEAD(&artxq->list);
}

[firmware has just crashed]

Dec 01 14:43:06 wave2 kernel: ------------[ cut here ]------------
Dec 01 14:43:06 wave2 kernel: WARNING: CPU: 0 PID: 193 at /home/greearb/git/linux-4.7.dev.y/drivers/net/wireless/ath/ath10k/mac.c:4217 
ath10k_mac_txq_init+0x1a7/0x1b0 [ath10k_core]
Dec 01 14:43:06 wave2 kernel: Modules linked in: nf_conntrack_netlink nf_conntrack nfnetlink nf_defrag_ipv4 bridge 8021q garp mrp stp llc bnep bluetooth fuse 
macvlan pktgen rpcsec_gss_krb5 nfsv4 nfs fscache coretemp hwmon intel_rapl x86_pkg_temp_thermal intel_powerclamp snd_hda_codec_hdmi snd_hda_codec_realtek 
snd_hda_codec_generic kvm iTCO_wdt irqbypass iTCO_vendor_support ath10k_pci ath10k_core joydev ath snd_hda_intel mac80211 snd_hda_codec snd_hda_core snd_hwdep 
snd_seq snd_seq_device pcspkr cfg80211 snd_pcm snd_timer snd i2c_i801 lpc_ich shpchp soundcore tpm_tis tpm nfsd auth_rpcgss nfs_acl lockd grace sunrpc serio_raw 
i915 i2c_algo_bit ata_generic drm_kms_helper pata_acpi e1000e ptp drm pps_core i2c_core fjes video ipv6 [last unloaded: nf_conntrack]
Dec 01 14:43:06 wave2 kernel: CPU: 0 PID: 193 Comm: kworker/0:1 Not tainted 4.7.10+ #14
Dec 01 14:43:06 wave2 kernel: Hardware name: To be filled by O.E.M. To be filled by O.E.M./ChiefRiver, BIOS 4.6.5 06/07/2013
Dec 01 14:43:06 wave2 kernel: Workqueue: events_freezable ieee80211_restart_work [mac80211]
Dec 01 14:43:06 wave2 kernel:  ffffffffa0e29507 ffff8801d14f7920 ffffffff8169ed08 0000000000000000
Dec 01 14:43:06 wave2 kernel:  0000000000000000 ffff8801d14f7968 ffffffff811569bc ffff8801d14e4f00
Dec 01 14:43:06 wave2 kernel:  0000107900000001 ffff8800c43ec9a0 0000000000000027 ffff8800c43ec988
Dec 01 14:43:06 wave2 kernel: Call Trace:
Dec 01 14:43:06 wave2 kernel:  [<ffffffffa0e29507>] ? ath10k_mac_txq_init+0x1a7/0x1b0 [ath10k_core]
Dec 01 14:43:06 wave2 kernel:  [<ffffffff8169ed08>] dump_stack+0x85/0xcd
Dec 01 14:43:06 wave2 kernel:  [<ffffffff811569bc>] __warn+0x10c/0x130
Dec 01 14:43:06 wave2 kernel:  [<ffffffff81156b58>] warn_slowpath_null+0x18/0x20
Dec 01 14:43:06 wave2 kernel:  [<ffffffffa0e29507>] ath10k_mac_txq_init+0x1a7/0x1b0 [ath10k_core]
Dec 01 14:43:06 wave2 kernel:  [<ffffffffa0e3766f>] ath10k_sta_state+0x4ef/0x1350 [ath10k_core]
Dec 01 14:43:06 wave2 kernel:  [<ffffffff811e10ed>] ? mark_lock+0x6d/0x8a0
Dec 01 14:43:06 wave2 kernel:  [<ffffffffa0e37180>] ? ath10k_station_assoc+0x920/0x920 [ath10k_core]
Dec 01 14:43:06 wave2 kernel:  [<ffffffff811ddd14>] ? __lock_is_held+0x84/0xc0
Dec 01 14:43:06 wave2 kernel:  [<ffffffffa0c0095f>] drv_sta_state+0xef/0xc50 [mac80211]
Dec 01 14:43:06 wave2 kernel:  [<ffffffffa0c6b1b0>] ieee80211_reconfig+0x10a0/0x2890 [mac80211]
Dec 01 14:43:06 wave2 kernel:  [<ffffffffa0bf8361>] ieee80211_restart_work+0xb1/0xf0 [mac80211]
Dec 01 14:43:06 wave2 kernel:  [<ffffffff81184dad>] process_one_work+0x42d/0xac0
Dec 01 14:43:06 wave2 kernel:  [<ffffffff81184cf4>] ? process_one_work+0x374/0xac0
Dec 01 14:43:06 wave2 kernel:  [<ffffffff81184980>] ? pwq_dec_nr_in_flight+0x110/0x110
Dec 01 14:43:06 wave2 kernel:  [<ffffffff811854c6>] worker_thread+0x86/0x730
Dec 01 14:43:06 wave2 kernel:  [<ffffffff81df25aa>] ? _raw_spin_unlock_irqrestore+0x5a/0x70
Dec 01 14:43:06 wave2 kernel:  [<ffffffff81185440>] ? process_one_work+0xac0/0xac0
Dec 01 14:43:06 wave2 kernel:  [<ffffffff8118f381>] kthread+0x191/0x1b0
Dec 01 14:43:06 wave2 kernel:  [<ffffffff8118f1f0>] ? kthread_create_on_node+0x320/0x320
Dec 01 14:43:06 wave2 kernel:  [<ffffffff8119baa3>] ? preempt_count_sub+0x13/0xd0
Dec 01 14:43:06 wave2 kernel:  [<ffffffff81df2f8f>] ret_from_fork+0x1f/0x40
Dec 01 14:43:06 wave2 kernel:  [<ffffffff8118f1f0>] ? kthread_create_on_node+0x320/0x320
Dec 01 14:43:06 wave2 kernel: ---[ end trace e64bc8f0c1a2531b ]---
Dec 01 14:43:06 wave2 kernel: ath10k_pci 0000:05:00.0: txq-init: Found txq when it should be deleted, txq_tmp: ffff8800c43ec988  txq: ffff8800c43ec988
Dec 01 14:43:07 wave2 kernel: ath10k_pci 0000:05:00.0: dropping dbg buffer due to crash since read

Thanks,
Ben

-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com