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From:   Mark Asselstine <asselsm@gmail.com>
Date:   Fri, 3 Apr 2020 13:10:31 -0400
Message-ID: <CAPuovE+Pmh71BNWdKEBJYYVhuowL3XABMyDtk6kbFTzfSR3M+g@mail.gmail.com>
Subject: Re: [PATCH v5.7 4/8] iwlwifi: mvm: limit maximum queue appropriately
To:     Luca Coelho <luca@coelho.fi>
Cc:     kvalo@codeaurora.org,
        linux-wireless <linux-wireless@vger.kernel.org>
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On Fri, Apr 3, 2020 at 10:38 AM Mark Asselstine <asselsm@gmail.com> wrote:
>
> On Fri, Apr 3, 2020 at 4:32 AM Luca Coelho <luca@coelho.fi> wrote:
> >
> > From: Johannes Berg <johannes.berg@intel.com>
> >
> > Due to some hardware issues, queue 32 isn't usable on devices that have
> > 32 queues (7000, 8000, 9000 families),

Is this statement really correct? All these devices have 31 queues
according to (.num_of_queues = 31). Without a HW specification I can't
be 100% sure but you should have this information within Intel. From
the details of my patch and my investigation, this should be nack'd
along with an explanation as to why my fix is not valid.

Mark

> > which is correctly reflected in
> > the configuration and TX queue initialization.
>
> This will not fix the issue on the 1000, 2000, 5000 and 6000 devices.
> You need further protection on these as their are only 20
> (IWLAGN_NUM_QUEUES) queues. I sent out a patch on March 19th with a
> fix.
>
> Mark
>
> >
> > However, the firmware API and queue allocation code assumes that there
> > are 32 queues, and if something actually attempts to use #31 this leads
> > to a NULL-pointer dereference since it's not allocated.
> >
> > Fix this by limiting to 31 in the IWL_MVM_DQA_MAX_DATA_QUEUE, and also
> > add some code to catch this earlier in the future, if the configuration
> > changes perhaps.
> >
> > Cc: stable@vger.kernel.org # v4.9+
> > Signed-off-by: Johannes Berg <johannes.berg@intel.com>
> > Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
> > ---
> >  drivers/net/wireless/intel/iwlwifi/fw/api/txq.h | 6 +++---
> >  drivers/net/wireless/intel/iwlwifi/mvm/sta.c    | 5 +++++
> >  2 files changed, 8 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/net/wireless/intel/iwlwifi/fw/api/txq.h b/drivers/net/wireless/intel/iwlwifi/fw/api/txq.h
> > index 73196cbc7fbe..75d958bab0e3 100644
> > --- a/drivers/net/wireless/intel/iwlwifi/fw/api/txq.h
> > +++ b/drivers/net/wireless/intel/iwlwifi/fw/api/txq.h
> > @@ -8,7 +8,7 @@
> >   * Copyright(c) 2007 - 2014 Intel Corporation. All rights reserved.
> >   * Copyright(c) 2013 - 2015 Intel Mobile Communications GmbH
> >   * Copyright(c) 2016 - 2017 Intel Deutschland GmbH
> > - * Copyright(c) 2019 Intel Corporation
> > + * Copyright(c) 2019 - 2020 Intel Corporation
> >   *
> >   * This program is free software; you can redistribute it and/or modify
> >   * it under the terms of version 2 of the GNU General Public License as
> > @@ -31,7 +31,7 @@
> >   * Copyright(c) 2005 - 2014 Intel Corporation. All rights reserved.
> >   * Copyright(c) 2013 - 2015 Intel Mobile Communications GmbH
> >   * Copyright(c) 2016 - 2017 Intel Deutschland GmbH
> > - * Copyright(c) 2019 Intel Corporation
> > + * Copyright(c) 2019 - 2020 Intel Corporation
> >   * All rights reserved.
> >   *
> >   * Redistribution and use in source and binary forms, with or without
> > @@ -99,7 +99,7 @@ enum iwl_mvm_dqa_txq {
> >         IWL_MVM_DQA_MAX_MGMT_QUEUE = 8,
> >         IWL_MVM_DQA_AP_PROBE_RESP_QUEUE = 9,
> >         IWL_MVM_DQA_MIN_DATA_QUEUE = 10,
> > -       IWL_MVM_DQA_MAX_DATA_QUEUE = 31,
> > +       IWL_MVM_DQA_MAX_DATA_QUEUE = 30,
> >  };
> >
> >  enum iwl_mvm_tx_fifo {
> > diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/sta.c b/drivers/net/wireless/intel/iwlwifi/mvm/sta.c
> > index 64ef3f3ba23b..251d6fbb1da5 100644
> > --- a/drivers/net/wireless/intel/iwlwifi/mvm/sta.c
> > +++ b/drivers/net/wireless/intel/iwlwifi/mvm/sta.c
> > @@ -722,6 +722,11 @@ static int iwl_mvm_find_free_queue(struct iwl_mvm *mvm, u8 sta_id,
> >
> >         lockdep_assert_held(&mvm->mutex);
> >
> > +       if (WARN(maxq >= mvm->trans->trans_cfg->base_params->num_of_queues,
> > +                "max queue %d >= num_of_queues (%d)", maxq,
> > +                mvm->trans->trans_cfg->base_params->num_of_queues))
> > +               maxq = mvm->trans->trans_cfg->base_params->num_of_queues - 1;
> > +
> >         /* This should not be hit with new TX path */
> >         if (WARN_ON(iwl_mvm_has_new_tx_api(mvm)))
> >                 return -ENOSPC;
> > --
> > 2.25.1
> >