Re: [PATCH] Fix e1000e with Intel 82572EI that has no hardware timestamp support

On 08/06/2014 12:03 PM, Nick Krause wrote:

On Wed, Aug 6, 2014 at 11:26 AM, Alexander Duyck
[off-list ref] wrote:

quoted

On 08/06/2014 08:21 AM, Alexander Duyck wrote:

quoted

On 08/06/2014 08:09 AM, Henrique de Moraes Holschuh wrote:

quoted

On Wed, Aug 6, 2014, at 11:30, Sergei Shtylyov wrote:

quoted

On 8/6/2014 6:27 PM, Koehrer Mathias (ETAS/ESW5) wrote:

quoted

With the Intel 82527EI (driver: e1000e) there is an issue when running
the ptpd2 program, that leads to a kernel oops.
The reason is here that in e1000_xmit_frame() a work queue will be
scheduled that has not been initialized in this case.
The work queue "tx_hwstamp_work" will only be initialized if
adapter->flags & FLAG_HAS_HW_TIMESTAMP set.
This check is missing in e1000_xmit_frame().

quoted

The following patch adds the missing check.

    OK, but this time you forgot your sign-off. :-)

Also, shouldn't the added test be inside the unlikely() ?

That shouldn't be necessary, but it might be better to place the new
check after the unlikely.  So you do the unlikely check first, then the
adapter check to see if we support Tx timestamping.  That way we can
avoid any unnecessary checks in the adapter structure.

Thanks,

Alex

Actually you might want to even take it one step further and break out
the test as follows (note this is only pseudo-code:
  unlikely(skb->tx_flags & HW_TSTAMP) &&
  (adapter->flags & HAS_HW_TSTAMP) &&
  !adapter->tx_hwtstamp_skb

There isn't much point in wrapping the entire statement in unlikely, by
wrapping just the first test the rest of the conditional checks can be
pushed into the branch which will likely require a jump to some remote
block of code and should streamline the hot-path.

Thanks,

Alex

Alex,
Has this patch been resent or not. If not I can clean it up and sent
as my own patch against linus's tree.
Regards NIck

Nick,

Please give Mathias a chance to complete his own patch.  Also this is
would be against Dave Miller's net tree, not Linus's tree.

Thanks,

Alex