Here is the function in question:
static void igb_cache_ring_register(struct igb_adapter *adapter)
{
int i = 0, j = 0;
u32 rbase_offset = adapter->vfs_allocated_count;
switch (adapter->hw.mac.type) {
case e1000_82576:
/* The queues are allocated for virtualization such that VF 0
* is allocated queues 0 and 8, VF 1 queues 1 and 9, etc.
* In order to avoid collision we start at the first free queue
* and continue consuming queues in the same sequence
*/
if ((adapter->rss_queues > 1) && adapter->vmdq_pools) {
for (; i < adapter->rss_queues; i++)
adapter->rx_ring[i]->reg_idx = rbase_offset +
Q_IDX_82576(i);
}
*** Q: should we break or fall through here? ***
case e1000_82575:
case e1000_82580:
case e1000_i350:
case e1000_i354:
case e1000_i210:
case e1000_i211:
/* Fall through */
default:
for (; i < adapter->num_rx_queues; i++)
adapter->rx_ring[i]->reg_idx = rbase_offset + i;
for (; j < adapter->num_tx_queues; j++)
adapter->tx_ring[j]->reg_idx = rbase_offset + j;
break;
}
}
The thing to note is that "i" and "j" are set to 0 at the top of the
function rather than being initialized in the for loops. So it might
make sense to run all three for loops:
top loop: init rx_ring[0 .. adapter->rss_queues - 1]
fall through
middle loop: init rx_ring[adapter->rss_queues .. adapter->num_rx_queues - 1]
bottom loop: init tx_ring[0 .. adapter->num_tx_queues - 1]
So the middle loop starts out with "i = adapter->rss_queues" rather than
"i = 0". If the loops started out with the more typical "for (i = 0;
...", then it would make less sense because then the middle loop would
undo the top loop.
But I am not familiar with this code, so if you still think that the fix
is incorrect, then I will submit the requested information to sourceforge.
Tony
On 01/07/2015 11:36 AM, Fujinaka, Todd wrote:
> NACK. The fix is incorrect and just invalidates the case statement in general.
>
> The TX hang message really doesn't tell you anything and it would be more
> useful to see the full logs. We'll need a lot more information to debug this
> issue. I would suggest filing the issue on sourceforge with all the usual
> full info:
>
> OS version
> Kernel version
> CPU information (model number and speed)
> Motherboard information (model number)
> Memory (how much, what speed, what size)
> dmesg
> ethtool -S ethX
> ethtool -i ethX
> cat /proc/interrupts
> cat /var/log/messages
> lspci -vvv
>
> Todd Fujinaka
> Software Application Engineer
> Networking Division (ND)
> Intel Corporation
> todd.fujin...@intel.com
> (503) 712-4565
>
> -----Original Message-----
> From: Tony Battersby [mailto:to...@cybernetics.com]
> Sent: Wednesday, January 07, 2015 6:59 AM
> To: e1000-devel@lists.sourceforge.net
> Subject: [E1000-devel] [PATCH] igb: fix Tx Unit Hang on 82576 with RSS > 1
>
> On my Supermicro X8DTH-6F motherboard, the onboard 82576 ethernet ports are
> completely inoperable with the latest igb from sourceforge when using RSS >
> 1. This is the error message:
>
> igb 0000:01:00.0: Detected Tx Unit Hang
> Tx Queue <0>
> TDH <0>
> TDT <1>
> next_to_use <1>
> next_to_clean <0>
> buffer_info[next_to_clean]
> time_stamp <10000b131>
> next_to_watch <ffff88032f1f4000>
> jiffies <10000b3b4>
> desc.status <a8000>
>
> Known-good versions:
> sourceforge igb-5.2.5.tar.gz and earlier
> upstream in-kernel igb
>
> Known-bad versions:
> sourceforge igb-5.2.9.2.tar.gz and later
>
> The patch below reverts the change that is causing the problem.
>
> Signed-off-by: Tony Battersby <to...@cybernetics.com>
> ---
>
> --- igb-5.2.15/src/igb_main.c.orig 2014-09-18 12:12:17.000000000 -0400
> +++ igb-5.2.15/src/igb_main.c 2015-01-06 17:47:07.000000000 -0500
> @@ -408,7 +408,7 @@ static void igb_cache_ring_register(stru
> adapter->rx_ring[i]->reg_idx = rbase_offset +
> Q_IDX_82576(i);
> }
> - break;
> + /* Fall through */
> case e1000_82575:
> case e1000_82580:
> case e1000_i350:
>
>
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