Hi, On Wed, Oct 28, 2020 at 8:47 AM Rakesh Pillai <pillair@xxxxxxxxxxxxxx> wrote: > > > -----Original Message----- > > From: Doug Anderson <dianders@xxxxxxxxxxxx> > > Sent: Wednesday, October 28, 2020 8:07 PM > > To: Rakesh Pillai <pillair@xxxxxxxxxxxxxx> > > Cc: ath10k <ath10k@xxxxxxxxxxxxxxxxxxx>; linux-wireless <linux- > > wireless@xxxxxxxxxxxxxxx>; LKML <linux-kernel@xxxxxxxxxxxxxxx>; Abhishek > > Kumar <kuabhs@xxxxxxxxxxxx>; Brian Norris <briannorris@xxxxxxxxxxxx> > > 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@xxxxxxxxxxxxxx> > > 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@xxxxxxxxxxxxxx> > > > --- > > > 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. I'm not sure I totally understood your response, but look at it from the perspective of the function ath10k_wmi_event_service_available(). That function calls: ret = ath10k_wmi_pull_svc_avail(ar, skb, &arg); ...if it gets back a non-zero error code, it assumes that the "arg.service_map_ext" and "arg.service_map_ext_len" values are now valid and it can use them. Before your patch, ath10k_wmi_pull_svc_avail() was returning an error code. That let ath10k_wmi_event_service_available() know that it shouldn't look at "arg.service_map_ext" and "arg.service_map_ext_len". After your patch, you're not returning an error code but those fields aren't being filled in. Said another way, if you remove the initialization of "arg" in ath10k_wmi_event_service_available() then everything is broken. While things work because you _do_ have an initialization of "arg" in ath10k_wmi_event_service_available(), it feels fragile to me to rely on that. -Doug