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Subject: Re: [v2,5/5] ath10k: Fix deadlock when peer cannot be created.
From: Kalle Valo <kvalo@qca.qualcomm.com>
In-Reply-To: <1459545132-11295-5-git-send-email-greearb@candelatech.com>
To: Ben Greear <greearb@candelatech.com>
CC: <ath10k@lists.infradead.org>, Ben Greear <greearb@candelatech.com>,
	<linux-wireless@vger.kernel.org>
Message-ID: <f7160429961449fc8729576118118606@euamsexm01a.eu.qualcomm.com> (sfid-20160606_192456_573236_47F37816)
Date: Mon, 6 Jun 2016 19:24:43 +0200
Sender: linux-wireless-owner@vger.kernel.org
List-ID: <linux-wireless.vger.kernel.org>

Ben Greear <greearb@candelatech.com> wrote:
> From: Ben Greear <greearb@candelatech.com>
> 
> We must not attempt to send WMI packets while holding the data-lock,
> as it may deadlock:
> 
> BUG: sleeping function called from invalid context at drivers/net/wireless/ath/ath10k/wmi.c:1824
> in_atomic(): 1, irqs_disabled(): 0, pid: 2878, name: wpa_supplicant
> 
> =============================================
> [ INFO: possible recursive locking detected ]
> 4.4.6+ #21 Tainted: G        W  O
> ---------------------------------------------
> wpa_supplicant/2878 is trying to acquire lock:
>  (&(&ar->data_lock)->rlock){+.-...}, at: [<ffffffffa0721511>] ath10k_wmi_tx_beacons_iter+0x26/0x11a [ath10k_core]
> 
> but task is already holding lock:
>  (&(&ar->data_lock)->rlock){+.-...}, at: [<ffffffffa070251b>] ath10k_peer_create+0x122/0x1ae [ath10k_core]
> 
> other info that might help us debug this:
>  Possible unsafe locking scenario:
> 
>        CPU0
>        ----
>   lock(&(&ar->data_lock)->rlock);
>   lock(&(&ar->data_lock)->rlock);
> 
>  *** DEADLOCK ***
> 
>  May be due to missing lock nesting notation
> 
> 4 locks held by wpa_supplicant/2878:
>  #0:  (rtnl_mutex){+.+.+.}, at: [<ffffffff816493ca>] rtnl_lock+0x12/0x14
>  #1:  (&ar->conf_mutex){+.+.+.}, at: [<ffffffffa0706932>] ath10k_add_interface+0x3b/0xbda [ath10k_core]
>  #2:  (&(&ar->data_lock)->rlock){+.-...}, at: [<ffffffffa070251b>] ath10k_peer_create+0x122/0x1ae [ath10k_core]
>  #3:  (rcu_read_lock){......}, at: [<ffffffffa062f304>] rcu_read_lock+0x0/0x66 [mac80211]
> 
> stack backtrace:
> CPU: 3 PID: 2878 Comm: wpa_supplicant Tainted: G        W  O    4.4.6+ #21
> Hardware name: To be filled by O.E.M. To be filled by O.E.M./ChiefRiver, BIOS 4.6.5 06/07/2013
>  0000000000000000 ffff8801fcadf8f0 ffffffff8137086d ffffffff82681720
>  ffffffff82681720 ffff8801fcadf9b0 ffffffff8112e3be ffff8801fcadf920
>  0000000100000000 ffffffff82681720 ffffffffa0721500 ffff8801fcb8d348
> Call Trace:
>  [<ffffffff8137086d>] dump_stack+0x81/0xb6
>  [<ffffffff8112e3be>] __lock_acquire+0xc5b/0xde7
>  [<ffffffffa0721500>] ? ath10k_wmi_tx_beacons_iter+0x15/0x11a [ath10k_core]
>  [<ffffffff8112d0d0>] ? mark_lock+0x24/0x201
>  [<ffffffff8112e908>] lock_acquire+0x132/0x1cb
>  [<ffffffff8112e908>] ? lock_acquire+0x132/0x1cb
>  [<ffffffffa0721511>] ? ath10k_wmi_tx_beacons_iter+0x26/0x11a [ath10k_core]
>  [<ffffffffa07214eb>] ? ath10k_wmi_cmd_send_nowait+0x1ce/0x1ce [ath10k_core]
>  [<ffffffff816f9e2b>] _raw_spin_lock_bh+0x31/0x40
>  [<ffffffffa0721511>] ? ath10k_wmi_tx_beacons_iter+0x26/0x11a [ath10k_core]
>  [<ffffffffa0721511>] ath10k_wmi_tx_beacons_iter+0x26/0x11a [ath10k_core]
>  [<ffffffffa07214eb>] ? ath10k_wmi_cmd_send_nowait+0x1ce/0x1ce [ath10k_core]
>  [<ffffffffa062eb18>] __iterate_interfaces+0x9d/0x13d [mac80211]
>  [<ffffffffa062f609>] ieee80211_iterate_active_interfaces_atomic+0x32/0x3e [mac80211]
>  [<ffffffffa07214eb>] ? ath10k_wmi_cmd_send_nowait+0x1ce/0x1ce [ath10k_core]
>  [<ffffffffa071fa9f>] ath10k_wmi_tx_beacons_nowait.isra.13+0x14/0x16 [ath10k_core]
>  [<ffffffffa0721676>] ath10k_wmi_cmd_send+0x71/0x242 [ath10k_core]
>  [<ffffffffa07023f6>] ath10k_wmi_peer_delete+0x3f/0x42 [ath10k_core]
>  [<ffffffffa0702557>] ath10k_peer_create+0x15e/0x1ae [ath10k_core]
>  [<ffffffffa0707004>] ath10k_add_interface+0x70d/0xbda [ath10k_core]
>  [<ffffffffa05fffcc>] drv_add_interface+0x123/0x1a5 [mac80211]
>  [<ffffffffa061554b>] ieee80211_do_open+0x351/0x667 [mac80211]
>  [<ffffffffa06158aa>] ieee80211_open+0x49/0x4c [mac80211]
>  [<ffffffff8163ecf9>] __dev_open+0x88/0xde
>  [<ffffffff8163ef6e>] __dev_change_flags+0xa4/0x13a
>  [<ffffffff8163f023>] dev_change_flags+0x1f/0x54
>  [<ffffffff816a5532>] devinet_ioctl+0x2b9/0x5c9
>  [<ffffffff816514dd>] ? copy_to_user+0x32/0x38
>  [<ffffffff816a6115>] inet_ioctl+0x81/0x9d
>  [<ffffffff816a6115>] ? inet_ioctl+0x81/0x9d
>  [<ffffffff81621cf8>] sock_do_ioctl+0x20/0x3d
>  [<ffffffff816223c4>] sock_ioctl+0x222/0x22e
>  [<ffffffff8121cf95>] do_vfs_ioctl+0x453/0x4d7
>  [<ffffffff81625603>] ? __sys_recvmsg+0x4c/0x5b
>  [<ffffffff81225af1>] ? __fget_light+0x48/0x6c
>  [<ffffffff8121d06b>] SyS_ioctl+0x52/0x74
>  [<ffffffff816fa736>] entry_SYSCALL_64_fastpath+0x16/0x7a
> 
> Signed-off-by: Ben Greear <greearb@candelatech.com>

Thanks, 1 patch applied to ath-current branch of ath.git:

fee48cf83745 ath10k: fix deadlock when peer cannot be created

-- 
Sent by pwcli
https://patchwork.kernel.org/patch/8727841/