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From:   Michael Nazzareno Trimarchi <michael@amarulasolutions.com>
Date:   Mon, 28 May 2018 11:54:31 +0200
Message-ID: <CAOf5uw=mPOgngZW8UcPfvtxH+5nCR-36ovjYPH7AvO99y1M_xA@mail.gmail.com>
Subject: Re: [PATCH] brcmfmac: stop watchdog before detach and free everything
To:     Arend van Spriel <arend.vanspriel@broadcom.com>
Cc:     Franky Lin <franky.lin@broadcom.com>,
        Hante Meuleman <hante.meuleman@broadcom.com>,
        Chi-Hsien Lin <chi-hsien.lin@cypress.com>,
        Wright Feng <wright.feng@cypress.com>,
        Kalle Valo <kvalo@codeaurora.org>,
        "David S. Miller" <davem@davemloft.net>,
        Pieter-Paul Giesberts <pieter-paul.giesberts@broadcom.com>,
        Ian Molton <ian@mnementh.co.uk>,
        linux-wireless@vger.kernel.org,
        brcm80211-dev-list.pdl@broadcom.com,
        brcm80211-dev-list@cypress.com, netdev@vger.kernel.org,
        LKML <linux-kernel@vger.kernel.org>
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Hi Arend

On Mon, May 28, 2018 at 11:51 AM, Arend van Spriel
<arend.vanspriel@broadcom.com> wrote:
> On 5/28/2018 9:50 AM, Michael Trimarchi wrote:
>>
>> Watchdog need to be stopped in brcmf_sdio_remove to avoid
>> i
>> The system is going down NOW!
>> [ 1348.110759] Unable to handle kernel NULL pointer dereference at virtual
>> address 000002f8
>> Sent SIGTERM to all processes
>> [ 1348.121412] Mem abort info:
>> [ 1348.126962]   ESR = 0x96000004
>> [ 1348.130023]   Exception class = DABT (current EL), IL = 32 bits
>> [ 1348.135948]   SET = 0, FnV = 0
>> [ 1348.138997]   EA = 0, S1PTW = 0
>> [ 1348.142154] Data abort info:
>> [ 1348.145045]   ISV = 0, ISS = 0x00000004
>> [ 1348.148884]   CM = 0, WnR = 0
>> [ 1348.151861] user pgtable: 4k pages, 48-bit VAs, pgdp = (____ptrval____)
>> [ 1348.158475] [00000000000002f8] pgd=0000000000000000
>> [ 1348.163364] Internal error: Oops: 96000004 [#1] PREEMPT SMP
>> [ 1348.168927] Modules linked in: ipv6
>> [ 1348.172421] CPU: 3 PID: 1421 Comm: brcmf_wdog/mmc0 Not tainted
>> 4.17.0-rc5-next-20180517 #18
>> [ 1348.180757] Hardware name: Amarula A64-Relic (DT)
>> [ 1348.185455] pstate: 60000005 (nZCv daif -PAN -UAO)
>> [ 1348.190251] pc : brcmf_sdiod_freezer_count+0x0/0x20
>> [ 1348.195124] lr : brcmf_sdio_watchdog_thread+0x64/0x290
>
>
> Hi Michael,
>
> Thanks for the patch. In normal scenario the callstack looks like this:
>
> brcmf_sdio_remove()
>         -> brcmf_detach()
>                 -> brcmf_bus_stop()
>                         -> brcmf_sdio_bus_stop()
>
> In brcmf_sdio_bus_stop() the watchdog is terminated. So in what scenario did
> you encounter this null pointer deref?

Is this happen even when there is not wifi firmware?
boot without any firmware in the filesystem and then trigger a reboot

Michael

>
> Regards,
> Arend


-- 
| Michael Nazzareno Trimarchi                     Amarula Solutions BV |
| COO  -  Founder                                      Cruquiuskade 47 |
| +31(0)851119172                                 Amsterdam 1018 AM NL |
|                  [`as] http://www.amarulasolutions.com               |