[PATCH] e1000 stop raw interrupts disabled nag from RT

[PATCH] e1000 stop raw interrupts disabled nag from RT

[Mark Huth]

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Current e1000_xmit_frame spews raw interrupt disabled nag messages when
used with RT kernel patches.  This patch uses spin_trylock_irqsave,
which allows RT patches to properly manage the irq semantics.

Signed-off-by: Mark Huth <mhuth@mvista.com>
---
diff --git a/drivers/net/e1000/e1000_main.c b/drivers/net/e1000/e1000_main.c
index 619c892..48f94ee 100644
--- a/drivers/net/e1000/e1000_main.c
+++ b/drivers/net/e1000/e1000_main.c
@@ -3363,12 +3363,9 @@ e1000_xmit_frame(struct sk_buff *skb, struct net_device *netdev)
 	    (adapter->hw.mac_type == e1000_82573))
 		e1000_transfer_dhcp_info(adapter, skb);
 
-	local_irq_save(flags);
-	if (!spin_trylock(&tx_ring->tx_lock)) {
+	if (!spin_trylock_irqsave(&tx_ring->tx_lock, flags))
 		/* Collision - tell upper layer to requeue */
-		local_irq_restore(flags);
 		return NETDEV_TX_LOCKED;
-	}
 
 	/* need: count + 2 desc gap to keep tail from touching
 	 * head, otherwise try next time */

Re: [PATCH] e1000 stop raw interrupts disabled nag from RT

[Kok, Auke]

Mark Huth wrote:
> Current e1000_xmit_frame spews raw interrupt disabled nag messages when
> used with RT kernel patches.  This patch uses spin_trylock_irqsave,
> which allows RT patches to properly manage the irq semantics.

Looks OK with me on first sight, I'll keep it on my stack and push it upstream 
after Jesse looks it over.

Which -RT paches make this pop up btw? I'd like to repro it.

Thanks,

Auke




> Signed-off-by: Mark Huth <mhuth@mvista.com>
> ---
> diff --git a/drivers/net/e1000/e1000_main.c b/drivers/net/e1000/e1000_main.c
> index 619c892..48f94ee 100644
> --- a/drivers/net/e1000/e1000_main.c
> +++ b/drivers/net/e1000/e1000_main.c
> @@ -3363,12 +3363,9 @@ e1000_xmit_frame(struct sk_buff *skb, struct net_device *netdev)
>  	    (adapter->hw.mac_type == e1000_82573))
>  		e1000_transfer_dhcp_info(adapter, skb);
>  
> -	local_irq_save(flags);
> -	if (!spin_trylock(&tx_ring->tx_lock)) {
> +	if (!spin_trylock_irqsave(&tx_ring->tx_lock, flags))
>  		/* Collision - tell upper layer to requeue */
> -		local_irq_restore(flags);
>  		return NETDEV_TX_LOCKED;
> -	}
>  
>  	/* need: count + 2 desc gap to keep tail from touching
>  	 * head, otherwise try next time */

Re: [PATCH] e1000 stop raw interrupts disabled nag from RT

[Mark Huth]

Kok, Auke wrote:
> Mark Huth wrote:
>> Current e1000_xmit_frame spews raw interrupt disabled nag messages when
>> used with RT kernel patches.  This patch uses spin_trylock_irqsave,
>> which allows RT patches to properly manage the irq semantics.
>
> Looks OK with me on first sight, I'll keep it on my stack and push it 
> upstream after Jesse looks it over.
>
> Which -RT paches make this pop up btw? I'd like to repro it.
>
> Thanks,
>
> Auke
Auke,

Well, I'm not an expert on the realtime patches - but most any patch set 
from Ingo seems to set this off - we've run through a bunch all the way 
since 2.6.10. It's a standard warning to get drivers to not mess with 
the processor interrupt function, since RT threads both the hard and 
soft irqs, and except for rare instances, the drivers and critical 
region protection no longer require the processor interrupt to be off.  
The XX_irqsave functions get turned into pre-empt disable, which is 
adequate for most things.  But the local_irq_save is recognized and 
warned, and then if it is really necessary it can be converted to an RT 
varient that won't warn.
>
>
>
>
>> Signed-off-by: Mark Huth <mhuth@mvista.com>
>> ---
>> diff --git a/drivers/net/e1000/e1000_main.c 
>> b/drivers/net/e1000/e1000_main.c
>> index 619c892..48f94ee 100644
>> --- a/drivers/net/e1000/e1000_main.c
>> +++ b/drivers/net/e1000/e1000_main.c
>> @@ -3363,12 +3363,9 @@ e1000_xmit_frame(struct sk_buff *skb, struct 
>> net_device *netdev)
>>          (adapter->hw.mac_type == e1000_82573))
>>          e1000_transfer_dhcp_info(adapter, skb);
>>  
>> -    local_irq_save(flags);
>> -    if (!spin_trylock(&tx_ring->tx_lock)) {
>> +    if (!spin_trylock_irqsave(&tx_ring->tx_lock, flags))
>>          /* Collision - tell upper layer to requeue */
>> -        local_irq_restore(flags);
>>          return NETDEV_TX_LOCKED;
>> -    }
>>  
>>      /* need: count + 2 desc gap to keep tail from touching
>>       * head, otherwise try next time */
>

Re: [PATCH] e1000 stop raw interrupts disabled nag from RT

[Kok, Auke]

Mark Huth wrote:
> Kok, Auke wrote:
>> Mark Huth wrote:
>>> Current e1000_xmit_frame spews raw interrupt disabled nag messages when
>>> used with RT kernel patches.  This patch uses spin_trylock_irqsave,
>>> which allows RT patches to properly manage the irq semantics.
>> Looks OK with me on first sight, I'll keep it on my stack and push it 
>> upstream after Jesse looks it over.
>>
>> Which -RT paches make this pop up btw? I'd like to repro it.
>>
> 
> Well, I'm not an expert on the realtime patches - but most any patch set 
> from Ingo seems to set this off - we've run through a bunch all the way 
> since 2.6.10.

that's bizarre, and would imply that Ingo himself never spotted this in ages, 
not to mention never tell us about it?

Ingo?

Re: [PATCH] e1000 stop raw interrupts disabled nag from RT

[Michal Schmidt]

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Kok, Auke wrote:
> Mark Huth wrote:
>> Well, I'm not an expert on the realtime patches - but most any patch set 
>> from Ingo seems to set this off - we've run through a bunch all the way 
>> since 2.6.10.
> 
> that's bizarre, and would imply that Ingo himself never spotted this in ages, 
> not to mention never tell us about it?

Ingo's -rt patches have contained this change to e1000 for some time.
The code is perfectly fine as is for non-RT kernels, so maybe that's why
noone felt like telling you about it.

Michal
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Re: [PATCH] e1000 stop raw interrupts disabled nag from RT

[Kok, Auke]

Michal Schmidt wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
> 
> Kok, Auke wrote:
>> Mark Huth wrote:
>>> Well, I'm not an expert on the realtime patches - but most any patch set 
>>> from Ingo seems to set this off - we've run through a bunch all the way 
>>> since 2.6.10.
>> that's bizarre, and would imply that Ingo himself never spotted this in ages, 
>> not to mention never tell us about it?
> 
> Ingo's -rt patches have contained this change to e1000 for some time.
> The code is perfectly fine as is for non-RT kernels, so maybe that's why
> noone felt like telling you about it.

uhh, sure... while we are at it then, are there any more patches like this? 
perhaps for e100? ixgb?

Cheers,

Auke

Re: [PATCH] e1000 stop raw interrupts disabled nag from RT

[Michal Schmidt]

Kok, Auke wrote:
> uhh, sure... while we are at it then, are there any more patches like this? 
> perhaps for e100? ixgb?

A quick grep through the current RT patch shows there are no other
changes to e100, e1000, ixgb.

Michal

Re: [PATCH] e1000 stop raw interrupts disabled nag from RT

[Mark Huth]

Michal Schmidt wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> Kok, Auke wrote:
>   
>> Mark Huth wrote:
>>     
>>> Well, I'm not an expert on the realtime patches - but most any patch set 
>>> from Ingo seems to set this off - we've run through a bunch all the way 
>>> since 2.6.10.
>>>       
>> that's bizarre, and would imply that Ingo himself never spotted this in ages, 
>> not to mention never tell us about it?
>>     
>
> Ingo's -rt patches have contained this change to e1000 for some time.
> The code is perfectly fine as is for non-RT kernels, so maybe that's why
> noone felt like telling you about it.
>
> Michal
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>
> iD8DBQFF5wlZabKV90ewf0QRAse3AJ979xur0u8X1DokSzaAMvLQCWPkXACfU9ss
> xC05DAbFNAaFMLnQrzBKit0=
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>   
Ah, tis true indeed.  This only shows up when one brings a newer driver 
forward after the RT patch has been applied.  I guess you would need to 
coordinate this with Ingo.

Thanks,
Mark Huth