Re: [PATCH RFC 1/2] brcmfmac: remove interface before notifying listener

From: "Rafał Miłecki" <zajec5@gmail.com>
To: Arend van Spriel <arend.vanspriel@broadcom.com>
Cc: Kalle Valo <kvalo@codeaurora.org>,
	Franky Lin <franky.lin@broadcom.com>,
	Hante Meuleman <hante.meuleman@broadcom.com>,
	Pieter-Paul Giesberts <pieter-paul.giesberts@broadcom.com>,
	"Franky (Zhenhui) Lin" <frankyl@broadcom.com>,
	"open list:BROADCOM BRCM80211 IEEE802.11n WIRELESS DRIVER"
	<linux-wireless@vger.kernel.org>,
	"open list:BROADCOM BRCM80211 IEEE802.11n WIRELESS DRIVER"
	<brcm80211-dev-list.pdl@broadcom.com>,
	"open list:NETWORKING DRIVERS" <netdev@vger.kernel.org>,
	open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH RFC 1/2] brcmfmac: remove interface before notifying listener
Date: Sun, 19 Jun 2016 00:42:58 +0200	[thread overview]
Message-ID: <CACna6rwwb3DNAcps6UyeRFvNTfhzh9ZiTTccPurhCzTn1SxcwQ@mail.gmail.com> (raw)
In-Reply-To: <CACna6rydCmKhyxsyOPrCsT_KbQLQPAg2doCcovVdvedBcRT+=w@mail.gmail.com>

On 18 June 2016 at 23:58, Rafał Miłecki <zajec5@gmail.com> wrote:
> On 18 June 2016 at 21:26, Arend van Spriel <arend.vanspriel@broadcom.com> wrote:
>> On 18-06-16 20:18, Rafał Miłecki wrote:
>>> So far when receiving event about in-firmware-interface removal we were
>>> notifying our listener and afterwards we were removing Linux interface.
>>>
>>
>> [snip]
>>
>>>
>>> diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fweh.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fweh.c
>>> index 9da7a4c..5fd1886 100644
>>> --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fweh.c
>>> +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fweh.c
>>> @@ -18,6 +18,7 @@
>>>  #include "brcmu_wifi.h"
>>>  #include "brcmu_utils.h"
>>>
>>> +#include "cfg80211.h"
>>>  #include "core.h"
>>>  #include "debug.h"
>>>  #include "tracepoint.h"
>>> @@ -180,10 +181,16 @@ static void brcmf_fweh_handle_if_event(struct brcmf_pub *drvr,
>>>       if (ifp && ifevent->action == BRCMF_E_IF_CHANGE)
>>>               brcmf_fws_reset_interface(ifp);
>>>
>>> -     err = brcmf_fweh_call_event_handler(ifp, emsg->event_code, emsg, data);
>>
>> The reason for doing this first is because we are passing the ifp, which
>> is netdev_priv(ifp->ndev). In brcmf_remove_interface() we only
>> unregister the netdev, which will end up (after scheduling) in
>> brcmf_free_netdev() thus freeing the ifp. By moving the event handler
>> function ifp may be stale already.
>
> Good catch. What about making brcmf_fweh_call_event_handler work
> without ifp? Would that be OK then?

Maybe I have even better idea. What about handling Linux interface
removal in the code waiting for BRCMF_E_IF_DEL? We already do
something like that in case of BRCMF_E_IF_ADD (it is brcmf_ap_add_vif
that calls brcmf_net_attach).