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Date:   Thu, 13 May 2021 10:18:22 -0700
From:   Jeff Johnson <jjohnson@codeaurora.org>
To:     Brian Norris <briannorris@chromium.org>
Cc:     Johannes Berg <johannes@sipsolutions.net>,
        linux-wireless <linux-wireless@vger.kernel.org>,
        Wen Gong <wgong@codeaurora.org>,
        stable <stable@vger.kernel.org>
Subject: Re: [PATCH 14/18] ath10k: drop MPDU which has discard flag set by
 firmware for SDIO
In-Reply-To: <CA+ASDXPwAWEEvWBdiLpMrm-PTcSH7QQHwx_T5nxN+faQt=Wi_g@mail.gmail.com>
References: <20210511180259.159598-1-johannes@sipsolutions.net>
 <20210511200110.11968c725b5c.Idd166365ebea2771c0c0a38c78b5060750f90e17@changeid>
 <CA+ASDXPwAWEEvWBdiLpMrm-PTcSH7QQHwx_T5nxN+faQt=Wi_g@mail.gmail.com>
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On 2021-05-12 11:35, Brian Norris wrote:
> On Tue, May 11, 2021 at 11:03 AM Johannes Berg
> <johannes@sipsolutions.net> wrote:
>> --- a/drivers/net/wireless/ath/ath10k/htt_rx.c
>> +++ b/drivers/net/wireless/ath/ath10k/htt_rx.c
>> @@ -2312,6 +2312,11 @@ static bool ath10k_htt_rx_proc_rx_ind_hl(struct
>> ath10k_htt *htt,
>>         fw_desc = &rx->fw_desc;
>>         rx_desc_len = fw_desc->len;
>> 
>> +       if (fw_desc->u.bits.discard) {
>> +               ath10k_dbg(ar, ATH10K_DBG_HTT, "htt discard mpdu\n");
>> +               goto err;
>> +       }
>> +
>>         /* I have not yet seen any case where num_mpdu_ranges > 1.
>>          * qcacld does not seem handle that case either, so we 
>> introduce
>> the
>>          * same limitiation here as well.
>> diff --git a/drivers/net/wireless/ath/ath10k/rx_desc.h
>> b/drivers/net/wireless/ath/ath10k/rx_desc.h
>> index f2b6bf8f0d60..705b6295e466 100644
>> --- a/drivers/net/wireless/ath/ath10k/rx_desc.h
>> +++ b/drivers/net/wireless/ath/ath10k/rx_desc.h
>> @@ -1282,7 +1282,19 @@ struct fw_rx_desc_base {
>>  #define FW_RX_DESC_UDP              (1 << 6)
>> 
>>  struct fw_rx_desc_hl {
>> -       u8 info0;
>> +       union {
>> +               struct {
>> +               u8 discard:1,
>> +                  forward:1,
>> +                  any_err:1,
>> +                  dup_err:1,
>> +                  reserved:1,
>> +                  inspect:1,
>> +                  extension:2;
>> +               } bits;
>> +               u8 info0;
>> +       } u;
> 
> Am I misled here, or are you introducing endianness issues here? From 
> C99:
> 
> "The order of allocation of bit-fields within a unit (high-order to
> low-order or low-order to high-order) is implementation-defined."
> 
> Now, we're pretty well attuned to two implementations (big and little
> endian), and this should work for the most common one (little endian),
> but it's not wise to assume everyone is little endian.
> 
> Brian

This issue was identified in internal review, but due to the embargo 
expiring
we sent it out as-is since that is what had been tested. The author will 
have
a follow-up change to replace this.

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