netdev - Re: [PATCH] tg3: driver sleeps indefinitely when EEH errors exceed eeh_max

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Message-ID: <CACKFLimd0a=Y8WyvqCt4BD7SU_Cg1vQ=baKs6-uPv0dZuCm=mw@mail.gmail.com>
Date:   Mon, 15 Jun 2020 13:45:36 -0700
From:   Michael Chan <michael.chan@...adcom.com>
To:     David Christensen <drc@...ux.vnet.ibm.com>
Cc:     Netdev <netdev@...r.kernel.org>,
        Siva Reddy Kallam <siva.kallam@...adcom.com>,
        Prashant Sreedharan <prashant@...adcom.com>,
        Michael Chan <mchan@...adcom.com>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] tg3: driver sleeps indefinitely when EEH errors exceed eeh_max_freezes

On Mon, Jun 15, 2020 at 12:01 PM David Christensen
<drc@...ux.vnet.ibm.com> wrote:
>
> The driver function tg3_io_error_detected() calls napi_disable twice,
> without an intervening napi_enable, when the number of EEH errors exceeds
> eeh_max_freezes, resulting in an indefinite sleep while holding rtnl_lock.
>
> The function is called once with the PCI state pci_channel_io_frozen and
> then called again with the state pci_channel_io_perm_failure when the
> number of EEH failures in an hour exceeds eeh_max_freezes.
>
> Protecting the calls to napi_enable/napi_disable with a new state
> variable prevents the long sleep.

This works, but I think a simpler fix is to check tp->pcierr_recovery
in tg3_io_error_detected() and skip most of the tg3 calls (including
the one that disables NAPI) if the flag is true.