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

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Message-ID: <95bf20c6-a812-32ad-fd38-45cba7e10491@linux.vnet.ibm.com>
Date:   Mon, 15 Jun 2020 15:21:14 -0700
From:   David Christensen <drc@...ux.vnet.ibm.com>
To:     Michael Chan <michael.chan@...adcom.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 6/15/20 1:45 PM, Michael Chan wrote:
> 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.

This might be the smallest change that would work.  Does it make sense 
to the reader?

diff --git a/drivers/net/ethernet/broadcom/tg3.c 
b/drivers/net/ethernet/broadcom/tg3.c
index 7a3b22b35238..1f37c69d213d 100644
--- a/drivers/net/ethernet/broadcom/tg3.c
+++ b/drivers/net/ethernet/broadcom/tg3.c
@@ -18168,8 +18168,8 @@ static pci_ers_result_t 
tg3_io_error_detected(struct pci_dev *pdev,

         rtnl_lock();

-       /* We probably don't have netdev yet */
-       if (!netdev || !netif_running(netdev))
+       /* May be second call or maybe we don't have netdev yet */
+       if (tp->pcierr_recovery || !netdev || !netif_running(netdev))
                 goto done;

         /* We needn't recover from permanent error */