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From:   Kalle Valo <kvalo@codeaurora.org>
To:     Brian Norris <briannorris@chromium.org>
Cc:     <linux-kernel@vger.kernel.org>,
        Amitkumar Karwar <amitkarwar@gmail.com>,
        Nishant Sarmukadam <nishants@marvell.com>,
        Ganapathi Bhat <gbhat@marvell.com>,
        Xinming Hu <huxinming820@gmail.com>,
        linux-wireless@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [4.20 PATCH] Revert "mwifiex: restructure rx_reorder_tbl_lock usage"
References: <20181130175957.167031-1-briannorris@chromium.org>
Date:   Mon, 03 Dec 2018 14:37:33 +0200
In-Reply-To: <20181130175957.167031-1-briannorris@chromium.org> (Brian
        Norris's message of "Fri, 30 Nov 2018 09:59:57 -0800")
Message-ID: <87h8fug50y.fsf@codeaurora.org>
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Brian Norris <briannorris@chromium.org> writes:

> This reverts commit 5188d5453bc9380ccd4ae1086138dd485d13aef2, because it
> introduced lock recursion:
>
>   BUG: spinlock recursion on CPU#2, kworker/u13:1/395
>    lock: 0xffffffc0e28a47f0, .magic: dead4ead, .owner: kworker/u13:1/395, .owner_cpu: 2
>   CPU: 2 PID: 395 Comm: kworker/u13:1 Not tainted 4.20.0-rc4+ #2
>   Hardware name: Google Kevin (DT)
>   Workqueue: MWIFIEX_RX_WORK_QUEUE mwifiex_rx_work_queue [mwifiex]
>   Call trace:
>    dump_backtrace+0x0/0x140
>    show_stack+0x20/0x28
>    dump_stack+0x84/0xa4
>    spin_bug+0x98/0xa4
>    do_raw_spin_lock+0x5c/0xdc
>    _raw_spin_lock_irqsave+0x38/0x48
>    mwifiex_flush_data+0x2c/0xa4 [mwifiex]
>    call_timer_fn+0xcc/0x1c4
>    run_timer_softirq+0x264/0x4f0
>    __do_softirq+0x1a8/0x35c
>    do_softirq+0x54/0x64
>    netif_rx_ni+0xe8/0x120
>    mwifiex_recv_packet+0xfc/0x10c [mwifiex]
>    mwifiex_process_rx_packet+0x1d4/0x238 [mwifiex]
>    mwifiex_11n_dispatch_pkt+0x190/0x1ac [mwifiex]
>    mwifiex_11n_rx_reorder_pkt+0x28c/0x354 [mwifiex]
>    mwifiex_process_sta_rx_packet+0x204/0x26c [mwifiex]
>    mwifiex_handle_rx_packet+0x15c/0x16c [mwifiex]
>    mwifiex_rx_work_queue+0x104/0x134 [mwifiex]
>    worker_thread+0x4cc/0x72c
>    kthread+0x134/0x13c
>    ret_from_fork+0x10/0x18
>
> This was clearly not tested well at all. I simply performed 'wget' in a
> loop and it fell over within a few seconds.
>
> Fixes: 5188d5453bc9 ("mwifiex: restructure rx_reorder_tbl_lock usage")
> Cc: <stable@vger.kernel.org>
> Cc: Ganapathi Bhat <gbhat@marvell.com>
> Signed-off-by: Brian Norris <briannorris@chromium.org>
> ---
> This is a 4.19 regression, but IMO the revert should be merged ASAP.

Ok, I'll queue this for 4.20.

-- 
Kalle Valo