Patchwork Gianfar driver failing on MPC8641D based board

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Submitter Anton Vorontsov
Date Feb. 26, 2010, 3:14 a.m.
Message ID <20100226031452.GA11319@oksana.dev.rtsoft.ru>
Download mbox | patch
Permalink /patch/46304/
State RFC
Delegated to: David Miller
Headers show

Comments

Anton Vorontsov - Feb. 26, 2010, 3:14 a.m.
On Thu, Feb 25, 2010 at 07:53:30PM -0500, Paul Gortmaker wrote:
[...]
> I was able to reproduce it on an 8641D and bisected it down to this:
> 
> -----------
> commit a3bc1f11e9b867a4f49505ecac486a33af248b2e
> Author: Anton Vorontsov <avorontsov@ru.mvista.com>
> Date:   Tue Nov 10 14:11:10 2009 +0000
> 
>     gianfar: Revive SKB recycling

Thanks for the bisect. I have a guess why tx hangs in
SMP case. Could anyone try the patch down below?

[...]
> ...which probably explains why you weren't seeing it on non-SMP.
> I'd imagine it would show up on any of the e500mc boards too.

Yeah.. Pity, I don't have SMP boards anymore. I'll try
to get one though.


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Kumar Gopalpet-B05799 - Feb. 26, 2010, 4:58 a.m.
>-----Original Message-----
>From: Anton Vorontsov [mailto:avorontsov@ru.mvista.com] 
>Sent: Friday, February 26, 2010 8:45 AM
>To: Paul Gortmaker
>Cc: Martyn Welch; linuxppc-dev list; netdev@vger.kernel.org; 
>linux-kernel@vger.kernel.org; Kumar Gopalpet-B05799; 
>davem@davemloft.net; Kumar Gala
>Subject: Re: Gianfar driver failing on MPC8641D based board
>
>On Thu, Feb 25, 2010 at 07:53:30PM -0500, Paul Gortmaker wrote:
>[...]
>> I was able to reproduce it on an 8641D and bisected it down to this:
>> 
>> -----------
>> commit a3bc1f11e9b867a4f49505ecac486a33af248b2e
>> Author: Anton Vorontsov <avorontsov@ru.mvista.com>
>> Date:   Tue Nov 10 14:11:10 2009 +0000
>> 
>>     gianfar: Revive SKB recycling
>
>Thanks for the bisect. I have a guess why tx hangs in SMP 
>case. Could anyone try the patch down below?
>
>[...]
>> ...which probably explains why you weren't seeing it on non-SMP.
>> I'd imagine it would show up on any of the e500mc boards too.
>
>Yeah.. Pity, I don't have SMP boards anymore. I'll try to get 
>one though.
>
>
>diff --git a/drivers/net/gianfar.c b/drivers/net/gianfar.c 
>index 8bd3c9f..3ff3bd0 100644
>--- a/drivers/net/gianfar.c
>+++ b/drivers/net/gianfar.c
>@@ -2614,6 +2614,8 @@ static int gfar_poll(struct napi_struct 
>*napi, int budget)
> 			tx_queue = priv->tx_queue[rx_queue->qindex];
> 
> 			tx_cleaned += gfar_clean_tx_ring(tx_queue);
>+			if (!tx_cleaned && !tx_queue->num_txbdfree)
>+				tx_cleaned += 1; /* don't 
>complete napi */
> 			rx_cleaned_per_queue = 
>gfar_clean_rx_ring(rx_queue,
> 							
>budget_per_queue);
> 			rx_cleaned += rx_cleaned_per_queue;
>

Anton, 

There is also one more issue that I have been observing with the patch
"gianfar: Revive SKB recycling".
The issue is when I do a IPV4 forwarding test scenario with
bidirectional flows (SMP environment). I am using Spirent smart bits
(smartflow) for automation testing and I frequently observe smart flow
reporting "Rx packet counte greater than Tx packet count. Duplicate
packets might have been received".

To just get over the issue I have removed this patch and I didn't see
the issue.

To a certain extent I could get over the problem by using atomic_t for
num_txbdfree (atomic_add and atomic_dec instructions for updating the
num_txbdfree) and completely removing the spin_locks in the tx routines.

Also, I feel we might want to make some more changes to the
gfar_clean_tx_ring( ) and gfar_start_xmit() routines so that they can
operate parallely. 

I am really sorry for not posting it a bit earlier as I am caught up
with some urgent issues.

--

Thanks
Sandeep
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Martyn Welch - Feb. 26, 2010, 12:06 p.m.
Anton Vorontsov wrote:
> On Thu, Feb 25, 2010 at 07:53:30PM -0500, Paul Gortmaker wrote:
> [...]
>   
>> I was able to reproduce it on an 8641D and bisected it down to this:
>>
>> -----------
>> commit a3bc1f11e9b867a4f49505ecac486a33af248b2e
>> Author: Anton Vorontsov <avorontsov@ru.mvista.com>
>> Date:   Tue Nov 10 14:11:10 2009 +0000
>>
>>     gianfar: Revive SKB recycling
>>     
>
> Thanks for the bisect. I have a guess why tx hangs in
> SMP case. Could anyone try the patch down below?
>   

Yup, no problem. I'm afraid it doesn't resolve the problem for me.

> [...]
>   
>> ...which probably explains why you weren't seeing it on non-SMP.
>> I'd imagine it would show up on any of the e500mc boards too.
>>     
>
> Yeah.. Pity, I don't have SMP boards anymore. I'll try
> to get one though.
>
>
> diff --git a/drivers/net/gianfar.c b/drivers/net/gianfar.c
> index 8bd3c9f..3ff3bd0 100644
> --- a/drivers/net/gianfar.c
> +++ b/drivers/net/gianfar.c
> @@ -2614,6 +2614,8 @@ static int gfar_poll(struct napi_struct *napi, int budget)
>  			tx_queue = priv->tx_queue[rx_queue->qindex];
>  
>  			tx_cleaned += gfar_clean_tx_ring(tx_queue);
> +			if (!tx_cleaned && !tx_queue->num_txbdfree)
> +				tx_cleaned += 1; /* don't complete napi */
>  			rx_cleaned_per_queue = gfar_clean_rx_ring(rx_queue,
>  							budget_per_queue);
>  			rx_cleaned += rx_cleaned_per_queue;
>
Anton Vorontsov - Feb. 26, 2010, 2:35 p.m.
On Fri, Feb 26, 2010 at 12:06:15PM +0000, Martyn Welch wrote:
> Anton Vorontsov wrote:
> > On Thu, Feb 25, 2010 at 07:53:30PM -0500, Paul Gortmaker wrote:
> > [...]
> >   
> >> I was able to reproduce it on an 8641D and bisected it down to this:
> >>
> >> -----------
> >> commit a3bc1f11e9b867a4f49505ecac486a33af248b2e
> >> Author: Anton Vorontsov <avorontsov@ru.mvista.com>
> >> Date:   Tue Nov 10 14:11:10 2009 +0000
> >>
> >>     gianfar: Revive SKB recycling
> >>     
> >
> > Thanks for the bisect. I have a guess why tx hangs in
> > SMP case. Could anyone try the patch down below?
> >   
> 
> Yup, no problem. I'm afraid it doesn't resolve the problem for me.

Hm.. I found a p2020 board and I was able to reproduce the issue.
The patch down below fixed it completely for me... hm.

I'll look further, thanks!

> > [...]
> >   
> >> ...which probably explains why you weren't seeing it on non-SMP.
> >> I'd imagine it would show up on any of the e500mc boards too.
> >>     
> >
> > Yeah.. Pity, I don't have SMP boards anymore. I'll try
> > to get one though.
> >
> >
> > diff --git a/drivers/net/gianfar.c b/drivers/net/gianfar.c
> > index 8bd3c9f..3ff3bd0 100644
> > --- a/drivers/net/gianfar.c
> > +++ b/drivers/net/gianfar.c
> > @@ -2614,6 +2614,8 @@ static int gfar_poll(struct napi_struct *napi, int budget)
> >  			tx_queue = priv->tx_queue[rx_queue->qindex];
> >  
> >  			tx_cleaned += gfar_clean_tx_ring(tx_queue);
> > +			if (!tx_cleaned && !tx_queue->num_txbdfree)
> > +				tx_cleaned += 1; /* don't complete napi */
> >  			rx_cleaned_per_queue = gfar_clean_rx_ring(rx_queue,
> >  							budget_per_queue);
> >  			rx_cleaned += rx_cleaned_per_queue;
> >
Paul Gortmaker - Feb. 26, 2010, 2:52 p.m.
On 10-02-26 09:35 AM, Anton Vorontsov wrote:
> On Fri, Feb 26, 2010 at 12:06:15PM +0000, Martyn Welch wrote:
>> Anton Vorontsov wrote:
>>> On Thu, Feb 25, 2010 at 07:53:30PM -0500, Paul Gortmaker wrote:
>>> [...]
>>>
>>>> I was able to reproduce it on an 8641D and bisected it down to this:
>>>>
>>>> -----------
>>>> commit a3bc1f11e9b867a4f49505ecac486a33af248b2e
>>>> Author: Anton Vorontsov<avorontsov@ru.mvista.com>
>>>> Date:   Tue Nov 10 14:11:10 2009 +0000
>>>>
>>>>      gianfar: Revive SKB recycling
>>>>
>>>
>>> Thanks for the bisect. I have a guess why tx hangs in
>>> SMP case. Could anyone try the patch down below?
>>>
>>
>> Yup, no problem. I'm afraid it doesn't resolve the problem for me.
> 
> Hm.. I found a p2020 board and I was able to reproduce the issue.
> The patch down below fixed it completely for me... hm.

Interesting. I just tested the patch on the sbc8641d, and it
still has the issue with your patch applied.  I'm using NFSroot
just like Martyn was and it still appears bound up on that
gianfar tx lock.  I'll see if I can get a SysRq backtrace in
case that will help you see how it manages to get there...

Paul.

----

nfs: server not responding, still trying 

[repeated ~15 times, then...]
                      
INFO: task rc.sysinit:837 blocked for more than 120 seconds.                    
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.       
rc.sysinit    D 0fef73f4     0   837    836 0x00000000                          
Call Trace:                                                                     
[dfb7d9b0] [c000a144] __switch_to+0x8c/0xf8                                     
[dfb7d9d0] [c03443dc] schedule+0x380/0x954                                      
[dfb7da50] [c0344a0c] io_schedule+0x5c/0x90                                     
[dfb7da70] [c0074b0c] sync_page+0x4c/0x74                                       
[dfb7da80] [c0344f44] __wait_on_bit_lock+0xb0/0x148                             
[dfb7dab0] [c0074a8c] __lock_page+0x94/0xa4                                     
[dfb7dae0] [c0074d5c] find_lock_page+0x8c/0xa4                                  
[dfb7db00] [c0075674] filemap_fault+0x1ec/0x4fc                                 
[dfb7db40] [c008d548] __do_fault+0x98/0x53c                                     
[dfb7dba0] [c0018478] do_page_fault+0x2d0/0x500                                 
[dfb7dc50] [c00149d4] handle_page_fault+0xc/0x80                                
--- Exception: 301 at __clear_user+0x14/0x7c                                    
    LR = load_elf_binary+0x670/0x1270                                           
[dfb7dd10] [c00f6ca0] load_elf_binary+0x620/0x1270 (unreliable)                 
[dfb7dd90] [c00b1f78] search_binary_handler+0x17c/0x394                         
[dfb7dde0] [c00f4f50] load_script+0x274/0x288                                   
[dfb7de90] [c00b1f78] search_binary_handler+0x17c/0x394                         
[dfb7dee0] [c00b3580] do_execve+0x240/0x29c                                     
[dfb7df20] [c000a46c] sys_execve+0x68/0xa4                                      
[dfb7df40] [c00145a4] ret_from_syscall+0x0/0x38     

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Martyn Welch - Feb. 26, 2010, 3:18 p.m.
Paul Gortmaker wrote:
> On 10-02-26 09:35 AM, Anton Vorontsov wrote:
>   
>> On Fri, Feb 26, 2010 at 12:06:15PM +0000, Martyn Welch wrote:
>>     
>>> Anton Vorontsov wrote:
>>>       
>>>> On Thu, Feb 25, 2010 at 07:53:30PM -0500, Paul Gortmaker wrote:
>>>> [...]
>>>>
>>>>         
>>>>> I was able to reproduce it on an 8641D and bisected it down to this:
>>>>>
>>>>> -----------
>>>>> commit a3bc1f11e9b867a4f49505ecac486a33af248b2e
>>>>> Author: Anton Vorontsov<avorontsov@ru.mvista.com>
>>>>> Date:   Tue Nov 10 14:11:10 2009 +0000
>>>>>
>>>>>      gianfar: Revive SKB recycling
>>>>>
>>>>>           
>>>> Thanks for the bisect. I have a guess why tx hangs in
>>>> SMP case. Could anyone try the patch down below?
>>>>
>>>>         
>>> Yup, no problem. I'm afraid it doesn't resolve the problem for me.
>>>       
>> Hm.. I found a p2020 board and I was able to reproduce the issue.
>> The patch down below fixed it completely for me... hm.
>>     
>
> Interesting. I just tested the patch on the sbc8641d, and it
> still has the issue with your patch applied.  I'm using NFSroot
> just like Martyn was and it still appears bound up on that
> gianfar tx lock.  I'll see if I can get a SysRq backtrace in
> case that will help you see how it manages to get there...
>   

I've got a p2020ds here as well, so I'll give NFSroot on that a try with
your patch.

Martyn
Martyn Welch - Feb. 26, 2010, 3:34 p.m.
Martyn Welch wrote:
> Paul Gortmaker wrote:
>   
>> On 10-02-26 09:35 AM, Anton Vorontsov wrote:
>>   
>>     
>>> On Fri, Feb 26, 2010 at 12:06:15PM +0000, Martyn Welch wrote:
>>>     
>>>       
>>>> Anton Vorontsov wrote:
>>>>       
>>>>         
>>>>> On Thu, Feb 25, 2010 at 07:53:30PM -0500, Paul Gortmaker wrote:
>>>>> [...]
>>>>>
>>>>>         
>>>>>           
>>>>>> I was able to reproduce it on an 8641D and bisected it down to this:
>>>>>>
>>>>>> -----------
>>>>>> commit a3bc1f11e9b867a4f49505ecac486a33af248b2e
>>>>>> Author: Anton Vorontsov<avorontsov@ru.mvista.com>
>>>>>> Date:   Tue Nov 10 14:11:10 2009 +0000
>>>>>>
>>>>>>      gianfar: Revive SKB recycling
>>>>>>
>>>>>>           
>>>>>>             
>>>>> Thanks for the bisect. I have a guess why tx hangs in
>>>>> SMP case. Could anyone try the patch down below?
>>>>>
>>>>>         
>>>>>           
>>>> Yup, no problem. I'm afraid it doesn't resolve the problem for me.
>>>>       
>>>>         
>>> Hm.. I found a p2020 board and I was able to reproduce the issue.
>>> The patch down below fixed it completely for me... hm.
>>>     
>>>       
>> Interesting. I just tested the patch on the sbc8641d, and it
>> still has the issue with your patch applied.  I'm using NFSroot
>> just like Martyn was and it still appears bound up on that
>> gianfar tx lock.  I'll see if I can get a SysRq backtrace in
>> case that will help you see how it manages to get there...
>>   
>>     
>
> I've got a p2020ds here as well, so I'll give NFSroot on that a try with
> your patch.
>   

Out of 10 boot attempts, 7 failed.

Martyn
Anton Vorontsov - Feb. 26, 2010, 4:10 p.m.
On Fri, Feb 26, 2010 at 03:34:07PM +0000, Martyn Welch wrote:
[...]
> Out of 10 boot attempts, 7 failed.

OK, I see why. With ip=on (dhcp boot) it's much harder to trigger
it. With static ip config can I see the same.
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Paul Gortmaker - Feb. 26, 2010, 4:27 p.m.
On 10-02-26 11:10 AM, Anton Vorontsov wrote:
> On Fri, Feb 26, 2010 at 03:34:07PM +0000, Martyn Welch wrote:
> [...]
>> Out of 10 boot attempts, 7 failed.
> 
> OK, I see why. With ip=on (dhcp boot) it's much harder to trigger
> it. With static ip config can I see the same.

I'd kind of expected to see us stuck in gianfar on that lock, but
the SysRQ-T doesn't show us hung up anywhere in gianfar itself.
[This was on a base 2.6.33, with just a small sysrq fix patch]

Paul.

----------

SysRq : Changing Loglevel                                            
Loglevel set to 9                                                               
nfs: server not responding, still trying                          
SysRq : Show State                                                              
  task                PC stack   pid father                                     
init          D 0ff1c380     0     1      0 0x00000000                          
Call Trace:                                                                     
[df841a30] [c0009fc4] __switch_to+0x8c/0xf8                                     
[df841a50] [c0350160] schedule+0x354/0x92c                                      
[df841ae0] [c0331394] rpc_wait_bit_killable+0x2c/0x54                           
[df841af0] [c0350eb0] __wait_on_bit+0x9c/0x108                                  
[df841b10] [c0350fc0] out_of_line_wait_on_bit+0xa4/0xb4                         
[df841b40] [c0331cf0] __rpc_execute+0x16c/0x398                                 
[df841b90] [c0329abc] rpc_run_task+0x48/0x9c                                    
[df841ba0] [c0329c40] rpc_call_sync+0x54/0x88                                   
[df841bd0] [c015e780] nfs_proc_lookup+0x94/0xe8                                 
[df841c20] [c014eb60] nfs_lookup+0x12c/0x230                                    
[df841d50] [c00b9680] do_lookup+0x118/0x288                                     
[df841d80] [c00bb904] link_path_walk+0x194/0x1118                               
[df841df0] [c00bcb08] path_walk+0x8c/0x168                                      
[df841e20] [c00bcd6c] do_path_lookup+0x74/0x7c                                  
[df841e40] [c00be148] do_filp_open+0x5d4/0xba4                                  
[df841f10] [c00abe94] do_sys_open+0xac/0x190                                    
[df841f40] [c001437c] ret_from_syscall+0x0/0x38                                 
--- Exception: c01 at 0xff1c380                                                 
    LR = 0xfec6d98                                                              
kthreadd      S 00000000     0     2      0 0x00000000                          
Call Trace:                                                                     
[df843e50] [c002e788] wake_up_new_task+0x128/0x16c (unreliable)                 
[df843f10] [c0009fc4] __switch_to+0x8c/0xf8                                     
[df843f30] [c0350160] schedule+0x354/0x92c                                      
[df843fc0] [c004d154] kthreadd+0x130/0x134                                      
[df843ff0] [c00141a0] kernel_thread+0x4c/0x68                                   
migration/0   S 00000000     0     3      2 0x00000000                          
Call Trace:                                                                     
[df847de0] [ffffffff] 0xffffffff (unreliable)                                   
[df847ea0] [c0009fc4] __switch_to+0x8c/0xf8                                     
[df847ec0] [c0350160] schedule+0x354/0x92c                                      
[df847f50] [c002d074] migration_thread+0x29c/0x448                              
[df847fb0] [c004d020] kthread+0x80/0x84                                         
[df847ff0] [c00141a0] kernel_thread+0x4c/0x68                                   
ksoftirqd/0   S 00000000     0     4      2 0x00000000                          
Call Trace:                                                                     
[df84be10] [00000800] 0x800 (unreliable)                                        
[df84bed0] [c0009fc4] __switch_to+0x8c/0xf8                                     
[df84bef0] [c0350160] schedule+0x354/0x92c                                      
[df84bf80] [c0038454] run_ksoftirqd+0x14c/0x1e0                                 
[df84bfb0] [c004d020] kthread+0x80/0x84                                         
[df84bff0] [c00141a0] kernel_thread+0x4c/0x68                                   
watchdog/0    S 00000000     0     5      2 0x00000000                          
Call Trace:                                                                     
[df84dee0] [c0009fc4] __switch_to+0x8c/0xf8                                     
[df84df00] [c0350160] schedule+0x354/0x92c                                      
[df84df90] [c006b8e8] watchdog+0x48/0x88                                        
[df84dfb0] [c004d020] kthread+0x80/0x84                                         
[df84dff0] [c00141a0] kernel_thread+0x4c/0x68                                   
migration/1   S 00000000     0     6      2 0x00000000                          
Call Trace:                                                                     
[df84fea0] [c0009fc4] __switch_to+0x8c/0xf8                                     
[df84fec0] [c0350160] schedule+0x354/0x92c                                      
[df84ff50] [c002d074] migration_thread+0x29c/0x448                              
[df84ffb0] [c004d020] kthread+0x80/0x84                                         
[df84fff0] [c00141a0] kernel_thread+0x4c/0x68                                   
ksoftirqd/1   S 00000000     0     7      2 0x00000000                          
Call Trace:                                                                     
[df853ed0] [c0009fc4] __switch_to+0x8c/0xf8                                     
[df853ef0] [c0350160] schedule+0x354/0x92c                                      
[df853f80] [c0038454] run_ksoftirqd+0x14c/0x1e0                                 
[df853fb0] [c004d020] kthread+0x80/0x84                                         
[df853ff0] [c00141a0] kernel_thread+0x4c/0x68                                   
watchdog/1    S 00000000     0     8      2 0x00000000                          
Call Trace:                                                                     
[df857ee0] [c0009fc4] __switch_to+0x8c/0xf8                                     
[df857f00] [c0350160] schedule+0x354/0x92c                                      
[df857f90] [c006b8e8] watchdog+0x48/0x88                                        
[df857fb0] [c004d020] kthread+0x80/0x84                                         
[df857ff0] [c00141a0] kernel_thread+0x4c/0x68                                   
events/0      S 00000000     0     9      2 0x00000000                          
Call Trace:                                                                     
[df859ea0] [c0009fc4] __switch_to+0x8c/0xf8                                     
[df859ec0] [c0350160] schedule+0x354/0x92c                                      
[df859f50] [c0048718] worker_thread+0x1fc/0x200                                 
[df859fb0] [c004d020] kthread+0x80/0x84                                         
[df859ff0] [c00141a0] kernel_thread+0x4c/0x68                                   
events/1      S 00000000     0    10      2 0x00000000                          
Call Trace:                                                                     
[df85bea0] [c0009fc4] __switch_to+0x8c/0xf8                                     
[df85bec0] [c0350160] schedule+0x354/0x92c                                      
[df85bf50] [c0048718] worker_thread+0x1fc/0x200                                 
[df85bfb0] [c004d020] kthread+0x80/0x84                                         
[df85bff0] [c00141a0] kernel_thread+0x4c/0x68                                   
khelper       S 00000000     0    11      2 0x00000000                          
Call Trace:                                                                     
[df85dde0] [c0030564] do_fork+0x1b0/0x344 (unreliable)                          
[df85dea0] [c0009fc4] __switch_to+0x8c/0xf8                                     
[df85dec0] [c0350160] schedule+0x354/0x92c                                      
[df85df50] [c0048718] worker_thread+0x1fc/0x200                                 
[df85dfb0] [c004d020] kthread+0x80/0x84                                         
[df85dff0] [c00141a0] kernel_thread+0x4c/0x68                                   
async/mgr     S 00000000     0    15      2 0x00000000                          
Call Trace:                                                                     
[df8a7df0] [000000fc] 0xfc (unreliable)                                         
[df8a7eb0] [c0009fc4] __switch_to+0x8c/0xf8                                     
[df8a7ed0] [c0350160] schedule+0x354/0x92c                                      
[df8a7f60] [c00565c0] async_manager_thread+0x120/0x174                          
[df8a7fb0] [c004d020] kthread+0x80/0x84                                         
[df8a7ff0] [c00141a0] kernel_thread+0x4c/0x68                                   
sync_supers   S 00000000     0    85      2 0x00000000                          
Call Trace:                                                                     
[df951e30] [00000400] 0x400 (unreliable)                                        
[df951ef0] [c0009fc4] __switch_to+0x8c/0xf8                                     
[df951f10] [c0350160] schedule+0x354/0x92c                                      
[df951fa0] [c008d714] bdi_sync_supers+0x30/0x5c                                 
[df951fb0] [c004d020] kthread+0x80/0x84                                         
[df951ff0] [c00141a0] kernel_thread+0x4c/0x68                                   
bdi-default   S 00000000     0    87      2 0x00000000                          
Call Trace:                                                                     
[df957e30] [c0009fc4] __switch_to+0x8c/0xf8                                     
[df957e50] [c0350160] schedule+0x354/0x92c                                      
[df957ee0] [c0350b14] schedule_timeout+0x15c/0x23c                              
[df957f30] [c008e510] bdi_forker_task+0x2f8/0x30c                               
[df957fb0] [c004d020] kthread+0x80/0x84                                         
[df957ff0] [c00141a0] kernel_thread+0x4c/0x68                                   
kblockd/0     S 00000000     0    88      2 0x00000000                          
Call Trace:                                                                     
[df8bdde0] [00000800] 0x800 (unreliable)                                        
[df8bdea0] [c0009fc4] __switch_to+0x8c/0xf8                                     
[df8bdec0] [c0350160] schedule+0x354/0x92c                                      
[df8bdf50] [c0048718] worker_thread+0x1fc/0x200                                 
[df8bdfb0] [c004d020] kthread+0x80/0x84                                         
[df8bdff0] [c00141a0] kernel_thread+0x4c/0x68                                   
kblockd/1     S 00000000     0    89      2 0x00000000                          
Call Trace:                                                                     
[df959de0] [00000800] 0x800 (unreliable)                                        
[df959ea0] [c0009fc4] __switch_to+0x8c/0xf8                                     
[df959ec0] [c0350160] schedule+0x354/0x92c                                      
[df959f50] [c0048718] worker_thread+0x1fc/0x200                                 
[df959fb0] [c004d020] kthread+0x80/0x84                                         
[df959ff0] [c00141a0] kernel_thread+0x4c/0x68                                   
rpciod/0      S 00000000     0   111      2 0x00000000                          
Call Trace:                                                                     
[df93fea0] [c0009fc4] __switch_to+0x8c/0xf8                                     
[df93fec0] [c0350160] schedule+0x354/0x92c                                      
[df93ff50] [c0048718] worker_thread+0x1fc/0x200                                 
[df93ffb0] [c004d020] kthread+0x80/0x84                                         
[df93fff0] [c00141a0] kernel_thread+0x4c/0x68                                   
rpciod/1      S 00000000     0   112      2 0x00000000                          
Call Trace:                                                                     
[df931de0] [00000001] 0x1 (unreliable)                                          
[df931ea0] [c0009fc4] __switch_to+0x8c/0xf8                                     
[df931ec0] [c0350160] schedule+0x354/0x92c                                      
[df931f50] [c0048718] worker_thread+0x1fc/0x200                                 
[df931fb0] [c004d020] kthread+0x80/0x84                                         
[df931ff0] [c00141a0] kernel_thread+0x4c/0x68                                   
khungtaskd    S 00000000     0   141      2 0x00000000                          
Call Trace:                                                                     
[df979db0] [00000800] 0x800 (unreliable)                                        
[df979e70] [c0009fc4] __switch_to+0x8c/0xf8                                     
[df979e90] [c0350160] schedule+0x354/0x92c                                      
[df979f20] [c0350b14] schedule_timeout+0x15c/0x23c                              
[df979f70] [c006bd38] watchdog+0x98/0x294                                       
[df979fb0] [c004d020] kthread+0x80/0x84                                         
[df979ff0] [c00141a0] kernel_thread+0x4c/0x68                                   
kswapd0       S 00000000     0   142      2 0x00000000                          
Call Trace:                                                                     
[df97bd60] [c04383a0] 0xc04383a0 (unreliable)                                   
[df97be20] [c0009fc4] __switch_to+0x8c/0xf8                                     
[df97be40] [c0350160] schedule+0x354/0x92c                                      
[df97bed0] [c00868a8] kswapd+0x81c/0x858                                        
[df97bfb0] [c004d020] kthread+0x80/0x84                                         
[df97bff0] [c00141a0] kernel_thread+0x4c/0x68                                   
aio/0         S 00000000     0   143      2 0x00000000                          
Call Trace:                                                                     
[df97dde0] [ffffffff] 0xffffffff (unreliable)                                   
[df97dea0] [c0009fc4] __switch_to+0x8c/0xf8                                     
[df97dec0] [c0350160] schedule+0x354/0x92c                                      
[df97df50] [c0048718] worker_thread+0x1fc/0x200                                 
[df97dfb0] [c004d020] kthread+0x80/0x84                                         
[df97dff0] [c00141a0] kernel_thread+0x4c/0x68                                   
aio/1         S 00000000     0   144      2 0x00000000                          
Call Trace:                                                                     
[df97fde0] [ffffffff] 0xffffffff (unreliable)                                   
[df97fea0] [c0009fc4] __switch_to+0x8c/0xf8                                     
[df97fec0] [c0350160] schedule+0x354/0x92c                                      
[df97ff50] [c0048718] worker_thread+0x1fc/0x200                                 
[df97ffb0] [c004d020] kthread+0x80/0x84                                         
[df97fff0] [c00141a0] kernel_thread+0x4c/0x68                                   
nfsiod        S 00000000     0   145      2 0x00000000                          
Call Trace:                                                                     
[df9a5de0] [00000003] 0x3 (unreliable)                                          
[df9a5ea0] [c0009fc4] __switch_to+0x8c/0xf8                                     
[df9a5ec0] [c0350160] schedule+0x354/0x92c                                      
[df9a5f50] [c0048718] worker_thread+0x1fc/0x200                                 
[df9a5fb0] [c004d020] kthread+0x80/0x84                                         
[df9a5ff0] [c00141a0] kernel_thread+0x4c/0x68                                   
crypto/0      S 00000000     0   146      2 0x00000000                          
Call Trace:                                                                     
[df9a7de0] [00000800] 0x800 (unreliable)                                        
[df9a7ea0] [c0009fc4] __switch_to+0x8c/0xf8                                     
[df9a7ec0] [c0350160] schedule+0x354/0x92c                                      
[df9a7f50] [c0048718] worker_thread+0x1fc/0x200                                 
[df9a7fb0] [c004d020] kthread+0x80/0x84                                         
[df9a7ff0] [c00141a0] kernel_thread+0x4c/0x68                                   
crypto/1      S 00000000     0   147      2 0x00000000                          
Call Trace:                                                                     
[df9a9ea0] [c0009fc4] __switch_to+0x8c/0xf8                                     
[df9a9ec0] [c0350160] schedule+0x354/0x92c                                      
[df9a9f50] [c0048718] worker_thread+0x1fc/0x200                                 
[df9a9fb0] [c004d020] kthread+0x80/0x84                                         
[df9a9ff0] [c00141a0] kernel_thread+0x4c/0x68                                   
mtdblockd     S 00000000     0   779      2 0x00000000                          
Call Trace:                                                                     
[dfae1e00] [00000800] 0x800 (unreliable)                                        
[dfae1ec0] [c0009fc4] __switch_to+0x8c/0xf8                                     
[dfae1ee0] [c0350160] schedule+0x354/0x92c                                      
[dfae1f70] [c02232dc] mtd_blktrans_thread+0x1c4/0x394                           
[dfae1fb0] [c004d020] kthread+0x80/0x84                                         
[dfae1ff0] [c00141a0] kernel_thread+0x4c/0x68                                   
kstriped      S 00000000     0   826      2 0x00000000                          
Call Trace:                                                                     
[df935de0] [00000800] 0x800 (unreliable)                                        
[df935ea0] [c0009fc4] __switch_to+0x8c/0xf8                                     
[df935ec0] [c0350160] schedule+0x354/0x92c                                      
[df935f50] [c0048718] worker_thread+0x1fc/0x200                                 
[df935fb0] [c004d020] kthread+0x80/0x84                                         
[df935ff0] [c00141a0] kernel_thread+0x4c/0x68                                   
ksnapd        S 00000000     0   828      2 0x00000000                          
Call Trace:                                                                     
[dfae9de0] [00000800] 0x800 (unreliable)                                        
[dfae9ea0] [c0009fc4] __switch_to+0x8c/0xf8                                     
[dfae9ec0] [c0350160] schedule+0x354/0x92c                                      
[dfae9f50] [c0048718] worker_thread+0x1fc/0x200                                 
[dfae9fb0] [c004d020] kthread+0x80/0x84                                         
[dfae9ff0] [c00141a0] kernel_thread+0x4c/0x68                                   
Sched Debug Version: v0.09, 2.6.33-00001-g8c31d07 #1                            
now at 35747.705693 msecs                                                       
  .jiffies                                 : 4294901234                         
  .sysctl_sched_latency                    : 10.000000                          
  .sysctl_sched_min_granularity            : 2.000000                           
  .sysctl_sched_wakeup_granularity         : 2.000000                           
  .sysctl_sched_child_runs_first           : 0.000000                           
  .sysctl_sched_features                   : 7917179                            
  .sysctl_sched_tunable_scaling            : 1 (logaritmic)                     
                                                                                
cpu#0                                                                           
  .nr_running                    : 0                                            
  .load                          : 0                                            
  .nr_switches                   : 2809                                         
  .nr_load_updates               : 8950                                         
  .nr_uninterruptible            : 1                                            
  .next_balance                  : 4294.901248                                  
  .curr->pid                     : 0                                            
  .clock                         : 35832.063536                                 
  .cpu_load[0]                   : 0                                            
  .cpu_load[1]                   : 0                                            
  .cpu_load[2]                   : 0                                            
  .cpu_load[3]                   : 0                                            
  .cpu_load[4]                   : 0                                            
                                                                                
cfs_rq[0] for UID: 0                                                            
  .exec_clock                    : 0.000000                                     
  .MIN_vruntime                  : 0.000001                                     
  .min_vruntime                  : 4129.195888                                  
  .max_vruntime                  : 0.000001                                     
  .spread                        : 0.000000                                     
  .spread0                       : 4048.261385                                  
  .nr_running                    : 0                                            
  .load                          : 0                                            
  .nr_spread_over                : 0                                            
  .shares                        : 0                                            
  .se->exec_start                : 35836.116992                                 
  .se->vruntime                  : 80.934503                                    
  .se->sum_exec_runtime          : 123.815984                                   
  .se->load.weight               : 1024                                         
                                                                                
rt_rq[0]:                                                                       
  .rt_nr_running                 : 0                                            
  .rt_throttled                  : 0                                            
  .rt_time                       : 0.000000                                     
  .rt_runtime                    : 950.000000                                   
                                                                                
runnable tasks:                                                                 
            task   PID         tree-key  switches  prio     exec-runtime        
 sum-exec        sum-sleep                                                      
--------------------------------------------------------------------------------
--------------------------                                                      
                                                                                
cpu#1                                                                           
  .nr_running                    : 0                                            
  .load                          : 0                                            
  .nr_switches                   : 4069                                         
  .nr_load_updates               : 8689                                         
  .nr_uninterruptible            : 0                                            
  .next_balance                  : 4294.901019                                  
  .curr->pid                     : 0                                            
  .clock                         : 34909.104304                                 
  .cpu_load[0]                   : 0                                            
  .cpu_load[1]                   : 0                                            
  .cpu_load[2]                   : 0                                            
  .cpu_load[3]                   : 0                                            
  .cpu_load[4]                   : 0                                            
                                                                                
cfs_rq[1] for UID: 0                                                            
  .exec_clock                    : 0.000000                                     
  .MIN_vruntime                  : 0.000001                                     
  .min_vruntime                  : 509.424556                                   
  .max_vruntime                  : 0.000001                                     
  .spread                        : 0.000000                                     
  .spread0                       : 428.490053                                   
  .nr_running                    : 0                                            
  .load                          : 0                                            
  .nr_spread_over                : 0                                            
  .shares                        : 0                                            
  .se->exec_start                : 34909.104304                                 
  .se->vruntime                  : 273.153007                                   
  .se->sum_exec_runtime          : 503.971344                                   
  .se->load.weight               : 1024                                         
                                                                                
rt_rq[1]:                                                                       
  .rt_nr_running                 : 0                                            
  .rt_throttled                  : 0                                            
  .rt_time                       : 0.000000                                     
  .rt_runtime                    : 950.000000                                   
                                                                                
runnable tasks:                                                                 
            task   PID         tree-key  switches  prio     exec-runtime        
 sum-exec        sum-sleep                                                      
--------------------------------------------------------------------------------
--------------------------                                                      
                              
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Patch

diff --git a/drivers/net/gianfar.c b/drivers/net/gianfar.c
index 8bd3c9f..3ff3bd0 100644
--- a/drivers/net/gianfar.c
+++ b/drivers/net/gianfar.c
@@ -2614,6 +2614,8 @@  static int gfar_poll(struct napi_struct *napi, int budget)
 			tx_queue = priv->tx_queue[rx_queue->qindex];
 
 			tx_cleaned += gfar_clean_tx_ring(tx_queue);
+			if (!tx_cleaned && !tx_queue->num_txbdfree)
+				tx_cleaned += 1; /* don't complete napi */
 			rx_cleaned_per_queue = gfar_clean_rx_ring(rx_queue,
 							budget_per_queue);
 			rx_cleaned += rx_cleaned_per_queue;