Subject: Re: [PATCH V2] brcmfmac: stop watchdog before detach and free everything

From: Arend van Spriel <[email-masked]>
Date: Tue, 19 Jun 2018 20:19:12 +0200

On 5/30/2018 11:06 AM, Michael Trimarchi wrote:
> Using built-in in kernel image without a firmware in filesystem
> or in the kernel image can lead to a kernel NULL pointer deference.
> Watchdog need to be stopped in brcmf_sdio_remove
>
> 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
> [ 1348.200253] sp : ffff00000b85be30
> [ 1348.203561] x29: ffff00000b85be30 x28: 0000000000000000
> [ 1348.208868] x27: ffff00000b6cb918 x26: ffff80003b990638
> [ 1348.214176] x25: ffff0000087b1a20 x24: ffff80003b94f800
> [ 1348.219483] x23: ffff000008e620c8 x22: ffff000008f0b660
> [ 1348.224790] x21: ffff000008c6a858 x20: 00000000fffffe00
> [ 1348.230097] x19: ffff80003b94f800 x18: 0000000000000001
> [ 1348.235404] x17: 0000ffffab2e8a74 x16: ffff0000080d7de8
> [ 1348.240711] x15: 0000000000000000 x14: 0000000000000400
> [ 1348.246018] x13: 0000000000000400 x12: 0000000000000001
> [ 1348.251324] x11: 00000000000002c4 x10: 0000000000000a10
> [ 1348.256631] x9 : ffff00000b85bc40 x8 : ffff80003be11870
> [ 1348.261937] x7 : ffff80003dfc7308 x6 : 000000078ff08b55
> [ 1348.267243] x5 : 00000139e1058400 x4 : 0000000000000000
> [ 1348.272550] x3 : dead000000000100 x2 : 958f2788d6618100
> [ 1348.277856] x1 : 00000000fffffe00 x0 : 0000000000000000

Forgot about this one.

Acked-by: Arend van Spriel <[email-masked]>
> Signed-off-by: Michael Trimarchi <[email-masked]>
> ---
>   drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c | 7 +++++++
>   1 file changed, 7 insertions(+)
>
> diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c
> index 412a05b..061f69d 100644
> --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c
> +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c
> @@ -4294,6 +4294,13 @@ void brcmf_sdio_remove(struct brcmf_sdio *bus)
>   	brcmf_dbg(TRACE, "Enter\n");
>
>   	if (bus) {
> +		/* Stop watchdog task */
> +		if (bus->watchdog_tsk) {
> +			send_sig(SIGTERM, bus->watchdog_tsk, 1);
> +			kthread_stop(bus->watchdog_tsk);
> +			bus->watchdog_tsk = NULL;
> +		}
> +
>   		/* De-register interrupt handler */
>   		brcmf_sdiod_intr_unregister(bus->sdiodev);
>
>