Re: [PATCH] brcmfmac: stop watchdog before detach and free everything

[Michael Nazzareno Trimarchi]

Hi Andy

The problem seems really easy to solve:

diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c
b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c
index 412a05b..ba60b151 100644
--- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c
+++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c
@@ -4227,13 +4227,7 @@ struct brcmf_sdio *brcmf_sdio_probe(struct
brcmf_sdio_dev *sdiodev)
        timer_setup(&bus->timer, brcmf_sdio_watchdog, 0);
        /* Initialize watchdog thread */
        init_completion(&bus->watchdog_wait);
-       bus->watchdog_tsk = kthread_run(brcmf_sdio_watchdog_thread,
-                                       bus, "brcmf_wdog/%s",
-                                       dev_name(&sdiodev->func1->dev));
-       if (IS_ERR(bus->watchdog_tsk)) {
-               pr_warn("brcmf_watchdog thread failed to start\n");
-               bus->watchdog_tsk = NULL;
-       }
+
        /* Initialize DPC thread */
        bus->dpc_triggered = false;
        bus->dpc_running = false;
@@ -4281,6 +4275,14 @@ struct brcmf_sdio *brcmf_sdio_probe(struct
brcmf_sdio_dev *sdiodev)
                goto fail;
        }

+       bus->watchdog_tsk = kthread_run(brcmf_sdio_watchdog_thread,
+                                       bus, "brcmf_wdog/%s",
+                                       dev_name(&sdiodev->func1->dev));
+       if (IS_ERR(bus->watchdog_tsk)) {
+               pr_warn("brcmf_watchdog thread failed to start\n");
+               bus->watchdog_tsk = NULL;
+       }
+
        return bus;

Just look here

        ret = brcmf_fw_get_firmwares(sdiodev->dev, fwreq,
                                     brcmf_sdio_firmware_callback);
        if (ret != 0) {
                brcmf_err("async firmware request failed: %d\n", ret);
                kfree(fwreq);
                goto fail;
        }

        bus->watchdog_tsk = kthread_run(brcmf_sdio_watchdog_thread,
                                        bus, "brcmf_wdog/%s",
                                        dev_name(&sdiodev->func1->dev));
        if (IS_ERR(bus->watchdog_tsk)) {
                pr_warn("brcmf_watchdog thread failed to start\n");
                bus->watchdog_tsk = NULL;
        }

        return bus;

fail:
        brcmf_sdio_remove(bus);
        return NULL;


On Mon, May 28, 2018 at 5:29 PM, Michael Nazzareno Trimarchi
<michael@xxxxxxxxxxxxxxxxxxxx> wrote:
> Hi
>
> On Mon, May 28, 2018 at 5:25 PM, Andy Shevchenko
> <andy.shevchenko@xxxxxxxxx> wrote:
>> On Mon, May 28, 2018 at 12:54 PM, Michael Nazzareno Trimarchi
>> <michael@xxxxxxxxxxxxxxxxxxxx> wrote:
>>> Hi Arend
>>>
>>> On Mon, May 28, 2018 at 11:51 AM, Arend van Spriel
>>> <arend.vanspriel@xxxxxxxxxxxx> 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
>>
>> Something like the above I had noticed for a long (couple of kernel
>> releases?) time, but wasn't a big priority to me.
>> Though, I can test this on my side.
>>
>> P.S. I think rmmod or echo > unbind will trigger that as well.
>>
>
> Right now the module is compiled in the kernel. I can dig down tonight
> on this if needed
>
> Michael
>
>> --
>> With Best Regards,
>> Andy Shevchenko
>
>
>
> --
> | Michael Nazzareno Trimarchi                     Amarula Solutions BV |
> | COO  -  Founder                                      Cruquiuskade 47 |
> | +31(0)851119172                                 Amsterdam 1018 AM NL |
> |                  [`as] http://www.amarulasolutions.com               |



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