netdev - Re: [PATCH net 2/2] bnxt_en: Fix NULL ptr dereference crash in bnxt_fw_reset

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Message-ID: <20200906201311.0873ad59@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Date:   Sun, 6 Sep 2020 20:13:11 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Michael Chan <michael.chan@...adcom.com>
Cc:     David Miller <davem@...emloft.net>,
        Netdev <netdev@...r.kernel.org>,
        Vasundhara Volam <vasundhara-v.volam@...adcom.com>
Subject: Re: [PATCH net 2/2] bnxt_en: Fix NULL ptr dereference crash in
 bnxt_fw_reset_task()

On Sun, 6 Sep 2020 15:07:02 -0700 Michael Chan wrote:
> On Sun, Sep 6, 2020 at 12:25 PM Jakub Kicinski <kuba@...nel.org> wrote:
> >
> > devlink can itself scheduler a recovery via:
> >
> >   bnxt_fw_fatal_recover() -> bnxt_fw_reset()
> >  
> 
> Yes, this is how it is initiated when we call devlink_health_report()
> to report the error condition.  From bnxt_fw_reset(), we use a
> workqueue because we have to go through many states, requiring
> sleeping/polling to transition through the states.
> 
> > no? Maybe don't make the devlink recovery path need to go via a
> > workqueue?  
> 
> Current implementation is going through a work queue.

What I'm saying is the code looks like this after this patch:

+	clear_bit(BNXT_STATE_IN_FW_RESET, &bp->state);
+	bnxt_cancel_sp_work(bp);
+	bp->sp_event = 0;
+
 	bnxt_dl_fw_reporters_destroy(bp, true);

It cancels the work, _then_ destroys the reporter. But I think the
reported can be used to schedule a recovery from command line. So the
work may get re-scheduled after it has been canceled.

devlink_nl_cmd_health_reporter_recover_doit() -> bnxt_fw_fatal_recover() ->
  bnxt_fw_reset() -> bnxt_queue_fw_reset_work()

What am I missing?