Re: [PATCH v2] cfg80211: avoid holding the RTNL when calling the driver

[Marek Szyprowski <m.szyprowski@samsung.com>]

Hi

On 25.01.2021 13:34, Johannes Berg wrote:
>> I've checked today's linux-next with the updated commit 27bc93583e35
>> ("cfg80211: avoid holding the RTNL when calling the driver") and there
>> is still an issue there, but at least it doesn't cause a deadlock:
>>
>> cfg80211: Loading compiled-in X.509 certificates for regulatory database
>> Bluetooth: vendor=0x2df, device=0x912a, class=255, fn=2
>> cfg80211: Loaded X.509 cert 'sforshee: 00b28ddf47aef9cea7'
>> Bluetooth: FW download over, size 533976 bytes
>> btmrvl_sdio mmc3:0001:2: sdio device tree data not available
>> mwifiex_sdio mmc3:0001:1: WLAN FW already running! Skip FW dnld
>> mwifiex_sdio mmc3:0001:1: WLAN FW is active
>> mwifiex_sdio mmc3:0001:1: CMD_RESP: cmd 0x242 error, result=0x2
>> mwifiex_sdio mmc3:0001:1: mwifiex_process_cmdresp: cmd 0x242 failed
>> during       initialization
>> ------------[ cut here ]------------
>> WARNING: CPU: 0 PID: 5 at net/wireless/core.c:1336
>> cfg80211_register_netdevice+0xa4/0x198 [cfg80211]
> Yeah, umm, brown paper bag style bug.
>
> I meant to _move_ that line down, but somehow managed to _copy_ it down.
> Need to just remove it since rdev is not even initialized at that point.
>
> I've updated my tree to include this:
>
> diff --git a/net/wireless/core.c b/net/wireless/core.c
> index 5e8b523dc645..200cd9f5fd5f 100644
> --- a/net/wireless/core.c
> +++ b/net/wireless/core.c
> @@ -1333,7 +1333,6 @@ int cfg80211_register_netdevice(struct net_device *dev)
>          int ret;
>   
>          ASSERT_RTNL();
> -       lockdep_assert_held(&rdev->wiphy.mtx);
>   
>          if (WARN_ON(!wdev))
>                  return -EINVAL;
>
Right, this finally fixed all the issues.

Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>

Best regards

-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland