[PATCH repost] netpoll: trapping fix/cleanup

[PATCH repost] netpoll: trapping fix/cleanup

[Sergei Shtylyov]

CONFIG_NETPOLL_TRAP causes the TX queue controls to be completely bypassed in
the netpoll's "trapped" mode which easily causes overflows in the drivers with
short TX queues (most notably, in 8139too with its 4-deep queue).
Make this option more sensible by only bypassing TX softirq wakeup and remove
CONFIG_NETPOLL_RX option completely since there is *no* code depending on it.

Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>

---
I wonder can I expect any motion with this patch (at least denial :-)?

 drivers/net/Kconfig       |    5 -----
 include/linux/netdevice.h |    8 +++-----
 2 files changed, 3 insertions(+), 10 deletions(-)

Index: linux-2.6/include/linux/netdevice.h
===================================================================
--- linux-2.6.orig/include/linux/netdevice.h
+++ linux-2.6/include/linux/netdevice.h
@@ -647,8 +647,10 @@ static inline void netif_start_queue(str
 static inline void netif_wake_queue(struct net_device *dev)
 {
 #ifdef CONFIG_NETPOLL_TRAP
-	if (netpoll_trap())
+	if (netpoll_trap()) {
+		clear_bit(__LINK_STATE_XOFF, &dev->state);
 		return;
+	}
 #endif
 	if (test_and_clear_bit(__LINK_STATE_XOFF, &dev->state))
 		__netif_schedule(dev);
@@ -656,10 +658,6 @@ static inline void netif_wake_queue(stru
 
 static inline void netif_stop_queue(struct net_device *dev)
 {
-#ifdef CONFIG_NETPOLL_TRAP
-	if (netpoll_trap())
-		return;
-#endif
 	set_bit(__LINK_STATE_XOFF, &dev->state);
 }
 
Index: linux-2.6/drivers/net/Kconfig
===================================================================
--- linux-2.6.orig/drivers/net/Kconfig
+++ linux-2.6/drivers/net/Kconfig
@@ -2928,11 +2928,6 @@ endif #NETDEVICES
 config NETPOLL
 	def_bool NETCONSOLE
 
-config NETPOLL_RX
-	bool "Netpoll support for trapping incoming packets"
-	default n
-	depends on NETPOLL
-
 config NETPOLL_TRAP
 	bool "Netpoll traffic trapping"
 	default n

Re: [PATCH repost] netpoll: trapping fix/cleanup

[Matt Mackall]

On Fri, Apr 27, 2007 at 11:44:00PM +0400, Sergei Shtylyov wrote:
> CONFIG_NETPOLL_TRAP causes the TX queue controls to be completely bypassed in
> the netpoll's "trapped" mode which easily causes overflows in the drivers with
> short TX queues (most notably, in 8139too with its 4-deep queue).
> Make this option more sensible by only bypassing TX softirq wakeup and remove
> CONFIG_NETPOLL_RX option completely since there is *no* code depending on it.

You've got two unrelated patches here, so that's an automatic NAK.

I suppose we can kill the config option.

What did you test the NETPOLL_TRAP test with?

-- 
Mathematics is the supreme nostalgia of our time.

Re: [PATCH repost] netpoll: trapping fix/cleanup

[Sergei Shtylyov]

Hello.

Matt Mackall wrote:

>>CONFIG_NETPOLL_TRAP causes the TX queue controls to be completely bypassed in
>>the netpoll's "trapped" mode which easily causes overflows in the drivers with
>>short TX queues (most notably, in 8139too with its 4-deep queue).
>>Make this option more sensible by only bypassing TX softirq wakeup and remove
>>CONFIG_NETPOLL_RX option completely since there is *no* code depending on it.
 
> You've got two unrelated patches here, so that's an automatic NAK.

   Come on, killing a long ago no-op option doesn't worth the sepearte patch. :-)

> I suppose we can kill the config option.

   I've even posted the refs to the commits introducing and killing the #ifdef's.

> What did you test the NETPOLL_TRAP test with?

   KGDBoE (and maybe also netconsole -- don't remember already).

WBR, Sergei

Re: [PATCH repost] netpoll: trapping fix/cleanup

[Matt Mackall]

On Sat, Apr 28, 2007 at 04:56:23PM +0400, Sergei Shtylyov wrote:
> Hello.
> 
> Matt Mackall wrote:
> 
> >>CONFIG_NETPOLL_TRAP causes the TX queue controls to be completely 
> >>bypassed in
> >>the netpoll's "trapped" mode which easily causes overflows in the drivers 
> >>with
> >>short TX queues (most notably, in 8139too with its 4-deep queue).
> >>Make this option more sensible by only bypassing TX softirq wakeup and 
> >>remove
> >>CONFIG_NETPOLL_RX option completely since there is *no* code depending on 
> >>it.
> 
> >You've got two unrelated patches here, so that's an automatic NAK.
> 
>   Come on, killing a long ago no-op option doesn't worth the sepearte 
>   patch. :-)
> 
> >I suppose we can kill the config option.
> 
>   I've even posted the refs to the commits introducing and killing the 
>   #ifdef's.
> 
> >What did you test the NETPOLL_TRAP test with?
> 
>   KGDBoE (and maybe also netconsole -- don't remember already).

Ok, KGDBoE is a pretty good test here. Netconsole isn't.

Please resend as two separate patches and add:

Acked-by: Matt Mackall <mpm@selenic.com>

-- 
Mathematics is the supreme nostalgia of our time.