linux-kernel - RE: [PATCH] ath10k: Fix the parsing error in service available event

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Message-ID: <003801d6ad41$a1bb8970$e5329c50$@codeaurora.org>
Date:   Wed, 28 Oct 2020 21:17:19 +0530
From:   "Rakesh Pillai" <pillair@...eaurora.org>
To:     "'Doug Anderson'" <dianders@...omium.org>
Cc:     "'ath10k'" <ath10k@...ts.infradead.org>,
        "'linux-wireless'" <linux-wireless@...r.kernel.org>,
        "'LKML'" <linux-kernel@...r.kernel.org>,
        "'Abhishek Kumar'" <kuabhs@...omium.org>,
        "'Brian Norris'" <briannorris@...omium.org>
Subject: RE: [PATCH] ath10k: Fix the parsing error in service available event



> -----Original Message-----
> From: Doug Anderson <dianders@...omium.org>
> Sent: Wednesday, October 28, 2020 8:07 PM
> To: Rakesh Pillai <pillair@...eaurora.org>
> Cc: ath10k <ath10k@...ts.infradead.org>; linux-wireless <linux-
> wireless@...r.kernel.org>; LKML <linux-kernel@...r.kernel.org>; Abhishek
> Kumar <kuabhs@...omium.org>; Brian Norris <briannorris@...omium.org>
> Subject: Re: [PATCH] ath10k: Fix the parsing error in service available event
> 
> Hi,
> 
> On Tue, Oct 27, 2020 at 8:20 AM Rakesh Pillai <pillair@...eaurora.org>
> wrote:
> >
> > The wmi service available event has been
> > extended to contain extra 128 bit for new services
> > to be indicated by firmware.
> >
> > Currently the presence of any optional TLVs in
> > the wmi service available event leads to a parsing
> > error with the below error message:
> > ath10k_snoc 18800000.wifi: failed to parse svc_avail tlv: -71
> >
> > The wmi service available event parsing should
> > not return error for the newly added optional TLV.
> > Fix this parsing for service available event message.
> >
> > Tested-on: WCN3990 hw1.0 SNOC
> >
> > Signed-off-by: Rakesh Pillai <pillair@...eaurora.org>
> > ---
> >  drivers/net/wireless/ath/ath10k/wmi-tlv.c | 3 +++
> >  1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/net/wireless/ath/ath10k/wmi-tlv.c
> b/drivers/net/wireless/ath/ath10k/wmi-tlv.c
> > index 932266d..3b49e29 100644
> > --- a/drivers/net/wireless/ath/ath10k/wmi-tlv.c
> > +++ b/drivers/net/wireless/ath/ath10k/wmi-tlv.c
> > @@ -1404,9 +1404,12 @@ static int ath10k_wmi_tlv_svc_avail_parse(struct
> ath10k *ar, u16 tag, u16 len,
> >                 arg->service_map_ext_len = *(__le32 *)ptr;
> >                 arg->service_map_ext = ptr + sizeof(__le32);
> >                 return 0;
> > +       case WMI_TLV_TAG_FIRST_ARRAY_ENUM:
> > +               return 0;
> 
> This is at least slightly worrying to me.  If I were calling this
> function, I'd expect that if I didn't get back an error that at least
> "arg->service_map_ext_len" was filled in.  Seems like you should do:
> 
> case WMI_TLV_TAG_FIRST_ARRAY_ENUM:
>   arg->service_map_ext_len = 0;
>   arg->service_map_ext = NULL;
>   return 0;
> 
> ...and maybe add a comment about why you're doing that?
> 
> At the moment things are working OK because
> ath10k_wmi_event_service_available() happens to init the structure to
> 0 before calling with:
> 
>   struct wmi_svc_avail_ev_arg arg = {};
> 
> ....but it doesn't seem like a great idea to rely on that.
> 
> That all being said, I'm just a drive-by reviewer and if everyone else
> likes it the way it is, feel free to ignore my comments.


Hi Doug,

The TLV TAG " WMI_TLV_TAG_STRUCT_SERVICE_AVAILABLE_EVENT" is the first and a mandatory TLV in the service available event.
The subsequent TLVs are optional ones and may or may not be present (based on FW versions).
This patch just fixes the bug, where the presence of any other TLVs are leading to a failure in parsing the service available msg.
If, in future, we plan to use any other services from firmware, which is exposed in the extended TLVs, we will need to add a new variable (and not service_map_ext) to set the service.


> 
> -Doug