* [PATCH] via-rhine: Fix tx_timeout handling
@ 2013-07-19 21:30 Richard Weinberger
2013-07-21 16:18 ` Ben Hutchings
0 siblings, 1 reply; 4+ messages in thread
From: Richard Weinberger @ 2013-07-19 21:30 UTC (permalink / raw)
To: rl; +Cc: netdev, linux-kernel, Richard Weinberger
rhine_reset_task() misses to call netif_stop_queue(),
this can lead to a crash if work is still scheduled while
we're resetting the tx queue.
Fixes:
[ 93.591707] BUG: unable to handle kernel NULL pointer dereference at 0000004c
[ 93.595514] IP: [<c119d10d>] rhine_napipoll+0x491/0x6e
Signed-off-by: Richard Weinberger <richard@nod.at>
---
drivers/net/ethernet/via/via-rhine.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/net/ethernet/via/via-rhine.c b/drivers/net/ethernet/via/via-rhine.c
index b75eb9e..57e1b40 100644
--- a/drivers/net/ethernet/via/via-rhine.c
+++ b/drivers/net/ethernet/via/via-rhine.c
@@ -1615,6 +1615,7 @@ static void rhine_reset_task(struct work_struct *work)
goto out_unlock;
napi_disable(&rp->napi);
+ netif_stop_queue(dev);
spin_lock_bh(&rp->lock);
/* clear all descriptors */
--
1.8.3.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] via-rhine: Fix tx_timeout handling
2013-07-19 21:30 [PATCH] via-rhine: Fix tx_timeout handling Richard Weinberger
@ 2013-07-21 16:18 ` Ben Hutchings
2013-07-21 16:32 ` Richard Weinberger
0 siblings, 1 reply; 4+ messages in thread
From: Ben Hutchings @ 2013-07-21 16:18 UTC (permalink / raw)
To: Richard Weinberger; +Cc: rl, netdev, linux-kernel
On Fri, 2013-07-19 at 23:30 +0200, Richard Weinberger wrote:
> rhine_reset_task() misses to call netif_stop_queue(),
> this can lead to a crash if work is still scheduled while
> we're resetting the tx queue.
>
> Fixes:
> [ 93.591707] BUG: unable to handle kernel NULL pointer dereference at 0000004c
> [ 93.595514] IP: [<c119d10d>] rhine_napipoll+0x491/0x6e
>
> Signed-off-by: Richard Weinberger <richard@nod.at>
> ---
> drivers/net/ethernet/via/via-rhine.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/net/ethernet/via/via-rhine.c b/drivers/net/ethernet/via/via-rhine.c
> index b75eb9e..57e1b40 100644
> --- a/drivers/net/ethernet/via/via-rhine.c
> +++ b/drivers/net/ethernet/via/via-rhine.c
> @@ -1615,6 +1615,7 @@ static void rhine_reset_task(struct work_struct *work)
> goto out_unlock;
>
> napi_disable(&rp->napi);
> + netif_stop_queue(dev);
This is not really fixing the bug because there is no synchronisation
with the TX scheduler. You can call netif_tx_disable() instead to do
that.
(I also think that it is preferable to use
netif_device_{detach,attach}() to stop the queue during reconfiguration,
as this is independent of TX completions and the watchdog.)
Ben.
> spin_lock_bh(&rp->lock);
>
> /* clear all descriptors */
--
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] via-rhine: Fix tx_timeout handling
2013-07-21 16:18 ` Ben Hutchings
@ 2013-07-21 16:32 ` Richard Weinberger
2013-07-21 20:24 ` Ben Hutchings
0 siblings, 1 reply; 4+ messages in thread
From: Richard Weinberger @ 2013-07-21 16:32 UTC (permalink / raw)
To: Ben Hutchings; +Cc: rl, netdev, linux-kernel
Am 21.07.2013 18:18, schrieb Ben Hutchings:
> On Fri, 2013-07-19 at 23:30 +0200, Richard Weinberger wrote:
>> rhine_reset_task() misses to call netif_stop_queue(),
>> this can lead to a crash if work is still scheduled while
>> we're resetting the tx queue.
>>
>> Fixes:
>> [ 93.591707] BUG: unable to handle kernel NULL pointer dereference at 0000004c
>> [ 93.595514] IP: [<c119d10d>] rhine_napipoll+0x491/0x6e
>>
>> Signed-off-by: Richard Weinberger <richard@nod.at>
>> ---
>> drivers/net/ethernet/via/via-rhine.c | 1 +
>> 1 file changed, 1 insertion(+)
>>
>> diff --git a/drivers/net/ethernet/via/via-rhine.c b/drivers/net/ethernet/via/via-rhine.c
>> index b75eb9e..57e1b40 100644
>> --- a/drivers/net/ethernet/via/via-rhine.c
>> +++ b/drivers/net/ethernet/via/via-rhine.c
>> @@ -1615,6 +1615,7 @@ static void rhine_reset_task(struct work_struct *work)
>> goto out_unlock;
>>
>> napi_disable(&rp->napi);
>> + netif_stop_queue(dev);
>
> This is not really fixing the bug because there is no synchronisation
> with the TX scheduler. You can call netif_tx_disable() instead to do
> that.
I guess other drivers suffer from that too.
A quick grep showed that not many drivers are using netif_tx_disable().
> (I also think that it is preferable to use
> netif_device_{detach,attach}() to stop the queue during reconfiguration,
> as this is independent of TX completions and the watchdog.)
So the correct down sequence is napi_disable() -> netif_tx_disable() -> netif_device_detach()?
Thanks,
//richard
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] via-rhine: Fix tx_timeout handling
2013-07-21 16:32 ` Richard Weinberger
@ 2013-07-21 20:24 ` Ben Hutchings
0 siblings, 0 replies; 4+ messages in thread
From: Ben Hutchings @ 2013-07-21 20:24 UTC (permalink / raw)
To: Richard Weinberger; +Cc: rl, netdev, linux-kernel
On Sun, 2013-07-21 at 18:32 +0200, Richard Weinberger wrote:
> Am 21.07.2013 18:18, schrieb Ben Hutchings:
> > On Fri, 2013-07-19 at 23:30 +0200, Richard Weinberger wrote:
> >> rhine_reset_task() misses to call netif_stop_queue(),
> >> this can lead to a crash if work is still scheduled while
> >> we're resetting the tx queue.
> >>
> >> Fixes:
> >> [ 93.591707] BUG: unable to handle kernel NULL pointer dereference at 0000004c
> >> [ 93.595514] IP: [<c119d10d>] rhine_napipoll+0x491/0x6e
> >>
> >> Signed-off-by: Richard Weinberger <richard@nod.at>
> >> ---
> >> drivers/net/ethernet/via/via-rhine.c | 1 +
> >> 1 file changed, 1 insertion(+)
> >>
> >> diff --git a/drivers/net/ethernet/via/via-rhine.c b/drivers/net/ethernet/via/via-rhine.c
> >> index b75eb9e..57e1b40 100644
> >> --- a/drivers/net/ethernet/via/via-rhine.c
> >> +++ b/drivers/net/ethernet/via/via-rhine.c
> >> @@ -1615,6 +1615,7 @@ static void rhine_reset_task(struct work_struct *work)
> >> goto out_unlock;
> >>
> >> napi_disable(&rp->napi);
> >> + netif_stop_queue(dev);
> >
> > This is not really fixing the bug because there is no synchronisation
> > with the TX scheduler. You can call netif_tx_disable() instead to do
> > that.
>
> I guess other drivers suffer from that too.
> A quick grep showed that not many drivers are using netif_tx_disable().
>
> > (I also think that it is preferable to use
> > netif_device_{detach,attach}() to stop the queue during reconfiguration,
> > as this is independent of TX completions and the watchdog.)
Actually, this is not independent of TX completions - netif_wake_queue()
will still start the TX scheduler while the device is not present, so
you have to avoid that.
> So the correct down sequence is napi_disable() -> netif_tx_disable() -> netif_device_detach()?
No, that's redundant. You can do:
napi_disable();
netif_tx_lock_bh(); /* sync with TX scheduler */
netif_device_detach();
netif_tx_unlock_bh();
and then when the queue is ready to use again:
netif_device_attach();
napi_enable();
Ben.
--
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2013-07-21 20:24 UTC | newest]
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2013-07-19 21:30 [PATCH] via-rhine: Fix tx_timeout handling Richard Weinberger
2013-07-21 16:18 ` Ben Hutchings
2013-07-21 16:32 ` Richard Weinberger
2013-07-21 20:24 ` Ben Hutchings
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