[net] tg3: prevent ifup/ifdown during PCI error recovery

The patch fixes race conditions between PCI error recovery callbacks and
potential ifup/ifdown.

First, if ifup (tg3_open) is called between tg3_io_error_detected() and
tg3_io_resume() then tp->timer is armed twice before expiry. Once during
tg3_open() and again during tg3_io_resume(). This results in BUG
at kernel/time/timer.c:945.

Second, if ifdown (tg3_close) is called between tg3_io_error_detected()
and tg3_io_resume() then tg3_napi_disable() is called twice without
a tg3_napi_enable between. Once during tg3_io_error_detected() and again
during tg3_close(). The tg3_io_resume() then hangs on rtnl_lock().

Cc: Prashant Sreedharan <prashant@broadcom.com>
Cc: Michael Chan <mchan@broadcom.com>

Signed-off-by: Ivan Vecera <ivecera@redhat.com>
---
 drivers/net/ethernet/broadcom/tg3.c | 10 ++++++++++
 drivers/net/ethernet/broadcom/tg3.h |  1 +
 2 files changed, 11 insertions(+)

Ivan, thanks for the patch. Minor comments.

>
> diff --git a/drivers/net/ethernet/broadcom/tg3.c b/drivers/net/ethernet/broadcom/tg3.c
> index 3ac5d23..8d9c774 100644
> --- a/drivers/net/ethernet/broadcom/tg3.c
> +++ b/drivers/net/ethernet/broadcom/tg3.c
> @@ -11617,6 +11617,9 @@ static int tg3_open(struct net_device *dev)
>   	struct tg3 *tp = netdev_priv(dev);
>   	int err;
>
> +	if (tp->pcierr_recovery)
> +		return -EAGAIN;
> +

Can have a netdev_err message here indicating the pcie error recovery 
that is taking place before returning.

>   	if (tp->fw_needed) {
>   		err = tg3_request_firmware(tp);
>   		if (tg3_asic_rev(tp) == ASIC_REV_57766) {
> @@ -11674,6 +11677,9 @@ static int tg3_close(struct net_device *dev)
>   {
>   	struct tg3 *tp = netdev_priv(dev);
>
> +	if (tp->pcierr_recovery)
> +		return -EAGAIN;
> +

netdev_err message here too.

>   	tg3_ptp_fini(tp);
>
>   	tg3_stop(tp);
> @@ -17561,6 +17567,7 @@ static int tg3_init_one(struct pci_dev *pdev,
>   	tp->rx_mode = TG3_DEF_RX_MODE;
>   	tp->tx_mode = TG3_DEF_TX_MODE;
>   	tp->irq_sync = 1;
> +	tp->pcierr_recovery = false;
>
>   	if (tg3_debug > 0)
>   		tp->msg_enable = tg3_debug;
> @@ -18071,6 +18078,8 @@ static pci_ers_result_t tg3_io_error_detected(struct pci_dev *pdev,
>
>   	rtnl_lock();
>
> +	tp->pcierr_recovery = true;
> +
>   	/* We probably don't have netdev yet */
>   	if (!netdev || !netif_running(netdev))
>   		goto done;
> @@ -18195,6 +18204,7 @@ static void tg3_io_resume(struct pci_dev *pdev)
>   	tg3_phy_start(tp);
>
>   done:
> +	tp->pcierr_recovery = false;
>   	rtnl_unlock();
>   }
>
> diff --git a/drivers/net/ethernet/broadcom/tg3.h b/drivers/net/ethernet/broadcom/tg3.h
> index 461acca..31c9f82 100644
> --- a/drivers/net/ethernet/broadcom/tg3.h
> +++ b/drivers/net/ethernet/broadcom/tg3.h
> @@ -3407,6 +3407,7 @@ struct tg3 {
>
>   	struct device			*hwmon_dev;
>   	bool				link_up;
> +	bool				pcierr_recovery;
>   };
>
>   /* Accessor macros for chip and asic attributes
>
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On 29.8.2014 01:28, Prashant wrote:
> Ivan, thanks for the patch. Minor comments.
>
>>
>> diff --git a/drivers/net/ethernet/broadcom/tg3.c
>> b/drivers/net/ethernet/broadcom/tg3.c
>> index 3ac5d23..8d9c774 100644
>> --- a/drivers/net/ethernet/broadcom/tg3.c
>> +++ b/drivers/net/ethernet/broadcom/tg3.c
>> @@ -11617,6 +11617,9 @@ static int tg3_open(struct net_device *dev)
>>       struct tg3 *tp = netdev_priv(dev);
>>       int err;
>>
>> +    if (tp->pcierr_recovery)
>> +        return -EAGAIN;
>> +
>
> Can have a netdev_err message here indicating the pcie error recovery
> that is taking place before returning.
Sure, done. V2 sent.

Ivan
>
>>       if (tp->fw_needed) {
>>           err = tg3_request_firmware(tp);
>>           if (tg3_asic_rev(tp) == ASIC_REV_57766) {
>> @@ -11674,6 +11677,9 @@ static int tg3_close(struct net_device *dev)
>>   {
>>       struct tg3 *tp = netdev_priv(dev);
>>
>> +    if (tp->pcierr_recovery)
>> +        return -EAGAIN;
>> +
>
> netdev_err message here too.
>
>>       tg3_ptp_fini(tp);
>>
>>       tg3_stop(tp);
>> @@ -17561,6 +17567,7 @@ static int tg3_init_one(struct pci_dev *pdev,
>>       tp->rx_mode = TG3_DEF_RX_MODE;
>>       tp->tx_mode = TG3_DEF_TX_MODE;
>>       tp->irq_sync = 1;
>> +    tp->pcierr_recovery = false;
>>
>>       if (tg3_debug > 0)
>>           tp->msg_enable = tg3_debug;
>> @@ -18071,6 +18078,8 @@ static pci_ers_result_t
>> tg3_io_error_detected(struct pci_dev *pdev,
>>
>>       rtnl_lock();
>>
>> +    tp->pcierr_recovery = true;
>> +
>>       /* We probably don't have netdev yet */
>>       if (!netdev || !netif_running(netdev))
>>           goto done;
>> @@ -18195,6 +18204,7 @@ static void tg3_io_resume(struct pci_dev *pdev)
>>       tg3_phy_start(tp);
>>
>>   done:
>> +    tp->pcierr_recovery = false;
>>       rtnl_unlock();
>>   }
>>
>> diff --git a/drivers/net/ethernet/broadcom/tg3.h
>> b/drivers/net/ethernet/broadcom/tg3.h
>> index 461acca..31c9f82 100644
>> --- a/drivers/net/ethernet/broadcom/tg3.h
>> +++ b/drivers/net/ethernet/broadcom/tg3.h
>> @@ -3407,6 +3407,7 @@ struct tg3 {
>>
>>       struct device            *hwmon_dev;
>>       bool                link_up;
>> +    bool                pcierr_recovery;
>>   };
>>
>>   /* Accessor macros for chip and asic attributes
>>

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