tree used it incorrectly, which lead to inaccurate overrated
if_obytes accounting. The drbr(9) used to update ifnet stats on
drbr_enqueue(), which is not accurate since enqueuing doesn't
imply successful processing by driver. Dequeuing neither mean
that. Most drivers also called drbr_stats_update() which did
accounting again, leading to doubled if_obytes statistics. And
in case of severe transmitting, when a packet could be several
times enqueued and dequeued it could have been accounted several
times.
o Thus, make drbr(9) API thinner. Now drbr(9) merely chooses between
ALTQ queueing or buf_ring(9) queueing.
- It doesn't touch the buf_ring stats any more.
- It doesn't touch ifnet stats anymore.
- drbr_stats_update() no longer exists.
o buf_ring(9) handles its stats itself:
- It handles br_drops itself.
- br_prod_bytes stats are dropped. Rationale: no one ever
reads them but update of a common counter on every packet
negatively affects performance due to excessive cache
invalidation.
- buf_ring_enqueue_bytes() reduced to buf_ring_enqueue(), since
we no longer account bytes.
o Drivers handle their stats theirselves: if_obytes, if_omcasts.
o mlx4(4), igb(4), em(4), vxge(4), oce(4) and ixv(4) no longer
use drbr_stats_update(), and update ifnet stats theirselves.
o bxe(4) was the most correct driver, it didn't call
drbr_stats_update(), thus it was the only driver accurate under
moderate load. Now it also maintains stats itself.
o ixgbe(4) had already taken stats from hardware, so just
- drop software stats updating.
- take multicast packet count from hardware as well.
o mxge(4) just no longer needs NO_SLOW_STATS define.
o cxgb(4), cxgbe(4) need no change, since they obtain stats
from hardware.
Reviewed by: jfv, gnn
- Use a dedicated task to handle deferred transmits from the if_transmit
method instead of reusing the existing per-queue interrupt task.
Reusing the per-queue interrupt task could result in both an interrupt
thread and the taskqueue thread trying to handle received packets on a
single queue resulting in out-of-order packet processing and lock
contention.
- Don't define ixgbe_start() at all where if_transmit is used.
Tested by: Vijay Singh
Reviewed by: jfv
MFC after: 2 weeks
adapter->dropped_pkts instead of if_ierrors because if_ierrors is
overwritten by hw stats collection.
Submitted by: Andrew Boyer <aboyer@averesystems.com>
Reviewed by: Jack F Vogel <jfv@freebsd.org>
MFC after: 2 weeks
#defines. This also has the advantage that it makes the names more
compact, iand also allows us to correct the non-uniform naming of
the PCIM_LINK_* defines, making them all consistent amongst themselves.
This is a mostly mechanical rename:
s/PCIR_EXPRESS_/PCIER_/g
s/PCIM_EXP_/PCIEM_/g
s/PCIM_LINK_/PCIEM_LINK_/g
When this is MFC'd, #defines will be added for the old names to assist
out-of-tree drivers.
Discussed with: jhb
MFC after: 1 week
"m_getjcl:invalid cluster type" that occurred some
time back with the igb driver. This happens often when
booting over the net. I believe the NIC hardware is left
in a warm state when handed over to the driver, and a stray
RX interrupt happens earlier than the code is prepared for
it to happen. This change was verified to fix the problem,
its kind of a bandaid... but it is similar to what was done
in the igb code.
packet delivery, always enqueue when possible. Also
correct the DEPLETED test as multiple bits might be
set. Thanks to Randall Stewart for the changes!
system with sparse CPU IDs, you can have a valid CPU ID > mp_ncpus (e.g. if
you have two CPUs 0 and 4, with mp_maxid == 4 and mp_ncpus == 2).
Introduced at svn r235210
Submitted by: jhb@
Reviewed by: jfv@
when used in qemu (and this driver is for non-PCIe cards,
so probably its largest use is in virtualized environments).
Approved by: Jack Vogel
MFC after: 3 days
setting in the igb and em driver. This was necessitated by
a shared code change that I was given late in the game, a data
type changed from bool to int, in the last update I dealt with
it by a cast, but it was pointed out (thanks jhb) that there
was a potential problem with this. John suggested this safer
approach, and it is fine with me...
MFC after:2 days (to catch the 9.1 update)
shared code update and small changes in core required
Add support for new i210/i211 devices
Improve queue calculation based on mac type
MFC after:5 days
as possible when using more than one igb(4) adapter. This
means that queues will not be bound to the same CPUs if
there are more CPUs availble.
This is only applicable to a system that has multiple interfaces.
Obtained from: Yahoo! Inc.
MFC after: 3 days
portions were already reapplied in r233708:
- Use a dedicated task to handle deferred transmits from the if_transmit
method instead of reusing the existing per-queue interrupt task.
Reusing the per-queue interrupt task could result in both an interrupt
thread and the taskqueue thread trying to handle received packets on a
single queue resulting in out-of-order packet processing.
- Call ether_ifdetach() earlier in igb_detach().
- Drain tasks and free taskqueues during igb_detach().
MFC after: 1 week
- Do not define the foo_start() methods or set if_start in the ifnet if
multiq transmit is enabled. Also, set if_transmit and if_qflush before
ether_ifattach rather than after when multiq transmit is enabled. This
helps to ensure that the drivers never try to mix different transmit
methods.
- Properly restart transmit during resume. igb(4) was not restarting it
at all, and em(4) was restarting even if the link was down and was
calling the wrong method if multiq transmit was enabled.
- Remove all the 'more' handling for transmit completions. Transmit
completion processing does not have a processing limit, so it always
runs to completion and never has more work to do when it returns.
Instead, the previous code was returning 'true' anytime there were
packets in the queue that weren't still in the process of being
transmitted. The effect was that the driver would continuously
reschedule a task to process TX completions in effect running at 100%
CPU polling the hardware until it finished transmitting all of the
packets in the ring. Now it will just wait for the next TX completion
interrupt.
- Restart packet transmission when the link becomes active.
- Fix the MSI-X queue interrupt handlers to restart packet transmission if
there are pending packets in the relevant software queue (IFQ or buf_ring)
after processing TX completions. This is the root cause for the OACTIVE
hangs as if the MSI-X queue handler drained all the pending packets from
the TX ring, nothing would ever restart it. As such, remove some
previously-added workarounds to reschedule a task to poll the TX ring
anytime OACTIVE was set.
Tested by: sbruno
Reviewed by: jfv
MFC after: 1 week
order to avoid otherwise harmless witness warnings when these are acquired
at the same time and due to both using MTX_NETWORK_LOCK as their type.
The right fix actually would be to use different, descriptive types for
these. However, the latter would require undesirable changes to the shared
code base. Another approach would be to just supply NULL as the type, which
was deemed as less desirable though as it would cause the unique but cryptic
name also to be used for the type and to diverge from the type used by other
network device drivers.
MFC after: 1 week
USERSPACE:
1. add support for devices with different number of rx and tx queues;
2. add better support for zero-copy operation, adding an extra field
to the netmap ring to indicate how many buffers we have already processed
but not yet released (with help from Eddie Kohler);
3. The two changes above unfortunately require an API change, so while
at it add a version field and some spares to the ioctl() argument
to help detect mismatches.
4. update the manual page for the two changes above;
5. update sample applications in tools/tools/netmap
KERNEL:
1. simplify the internal structures moving the global wait queues
to the 'struct netmap_adapter';
2. simplify the functions that map kring<->nic ring indexes
3. normalize device-specific code, helps mainteinance;
4. start exploring the impact of micro-optimizations (prefetch etc.)
in the ixgbe driver.
Use 'legacy' descriptors on the tx ring and prefetch slots gives
about 20% speedup at 900 MHz. Another 7-10% would come from removing
the explict calls to bus_dmamap* in the core (they are effectively
NOPs in this case, but it takes expensive load of the per-buffer
dma maps to figure out that they are all NULL.
Rx performance not investigated.
I am postponing the MFC so i can import a few more improvements
before merging.
Introduce some functions to map NIC ring indexes into netmap ring
indexes and vice versa. This way we can implement the bound
checks only in one place (and hopefully in a correct way).
On passing, make the code and comments more uniform across the
various drivers.
the memory allocator used by netmap. No functional change,
two small bug fixes:
- in if_re.c add a missing bus_dmamap_sync()
- in netmap.c comment out a spurious free() in an error handling block
rings, copy the whole VLAN tag, not just the VLAN ID. This fixes a
problem in which VLAN priority information was dropped when using
offloaded VLAN processing with these drivers.
Discussed with: jfv, rrs
Sponsored by: ADARA Networks, Inc.
MFC after: 3 days
import:
- Add read-only sysctls for all of the tunables supported by the igb and
em drivers.
- Make the per-instance 'enable_aim' sysctl truly per-instance by having it
change a per-instance variable (which is used to control AIM) rather
than having all of the per-instance sysctls operate on a single global
variable.
While here, restore the previously existing hw.igb.rx_processing_limit
tunable as it is very useful to be able to set a default tunable that
applies to all adapters in the system.
- Two struct members eee_disable are used in a function that expects
an int *, so declare them int, not bool.
- igb_tx_ctx_setup() returns a boolean value, so declare it bool, not int.
- igb_header_split is passed to TUNABLE_INT, so delcare it int, not bool.
- igb_tso_setup() returns a bool, so declare it bool, not boolean_t.
- Do not re-define bool/true/false if the symbols already exist.
MFC after: 2 weeks
Sponsored by: Isilon Systems, LLC
There have still been intermittent problems with apparent TX
hangs for some customers. These have been problematic to reproduce
but I believe these changes will address them. Testing on a number
of fronts have been positive.
EM: there is an important 'chicken bit' fix for 82574 in the shared
code this is supported in the core here.
- The TX path has been tightened up to improve performance. In
particular UDP with jumbo frames was having problems, and the
changes here have improved that.
- OACTIVE has been used more carefully on the theory that some
hangs may be due to a problem in this interaction
- Problems with the RX init code, the "lazy" allocation and
ring initialization has been found to cause problems in some
newer client systems, and as it really is not that big a win
(its not in a hot path) it seems best to remove it.
- HWTSO was broken when VLAN HWTAGGING or HWFILTER is used, I
found this was due to an error in setting up the descriptors
in em_xmit.
IGB:
- TX is also improved here. With multiqueue I realized its very
important to handle OACTIVE only under the CORE lock so there
are no races between the queues.
- Flow Control handling was broken in a couple ways, I have changed
and I hope improved that in this delta.
- UDP also had a problem in the TX path here, it was change to
improve that.
- On some hardware, with the driver static, a weird stray interrupt
seems to sometimes fire and cause a panic in the RX mbuf refresh
code. This is addressed by setting interrupts late in the init
path, and also to set all interrupts bits off at the start of that.
support of new deltas for both em and igb drivers.
Note that I am not able to track all the bugs fixed in
this code, I am a consumer of it as a component of my
core drivers. It is important to keep the FreeBSD drivers
up to date with it however.
One important note is there is a key fix for 82574 in this
update. Also, there are lots of white space changes, I am
not happy about them but have no control over it :)
On my hardware, "em" in netmap mode does about 1.388 Mpps
on one card (on an Asus motherboard), and 1.1 Mpps on another
card (PCIe bus). Both seem to be NIC-limited, because
i have the same rate even with the CPU running at 150 MHz.
On the "re" driver the tx throughput is around 420-450 Kpps
on various (8111C and the like) chipsets. On the Rx side
performance seems much better, and i can receive the full
load generated by the "em" cards.
"igb" is untested as i don't have the hardware.
The SYSCTL_NODE macro defines a list that stores all child-elements of
that node. If there's no SYSCTL_DECL macro anywhere else, there's no
reason why it shouldn't be static.
initialization. Prior to this change packets may be transmitted with an
incorrect checksum.
Em(4) already has an equivalent change in r213234.
Obtained From: Sandvine
MFC After: 1 week
Approved by: re (bz)
em drivers.
- Make the per-instance 'enable_aim' sysctl truly per-instance by having it
change a per-instance variable (which is used to control AIM) rather
than having all of the per-instance sysctls operate on a single global
variable.
Reviewed by: jfv (earlier version)
MFC after: 1 week
particular flow control and dma coalesce. Also improve the
sysctl operation on those too.
Add IPv6 detection in the ioctl code, this was done for
ixgbe first, carrying that over.
Add resource ability to disable particular adapter.
Add HW TSO capability so vlans can make use of TSO
method instead of reusing the existing per-queue interrupt task.
Reusing the per-queue interrupt task could result in both an interrupt
thread and the taskqueue thread trying to handle received packets on a
single queue resulting in out-of-order packet processing.
- Don't define igb_start() at all on 8.0 and where if_transmit is used.
Replace last remaining call to igb_start() with a loop to kick off
transmit on each queue instead.
- Call ether_ifdetach() earlier in igb_detach().
- Drain tasks and free taskqueues during igb_detach().
Reviewed by: jfv
MFC after: 1 week
this there is a rare return path that bogusly appears
to fail when it should not. Also white space correction.
Thanks to Arnaud Lacombe for noticing the problem.
- Add the change made in em to the actual unrefreshed number
of descriptors is used as a basis in rxeof on the way out
to determine if more refresh is needed. NOTE: there is a
difference in the ring setup in igb, this is not accidental,
it is necessitated by hardware behavior, when you reset the
newer adapters it will not let you write RDH, it ALWAYS sets
it to 0. Thus the way em does it is not possible.
- Change the sysctl handling of flow control, it will now make
the change dynamically when the variable setting changes rather
than requiring a reset.
- Change the eee sysctl naming, validation found the old unintuitive :)
- Last but not least, some important performance tweaks in the TX
path, I found that UDP behavior could be drastically hindered or
improved with just small changes in the start loop. What I have
here is what testing has shown to be the best overall. Its interesting
to note that changing the clean threshold to start at a full half of
the ring, made a BIG difference in performance. I hope that this
will prove to be advantageous for most workloads.
MFC in a week.
get's defragged due to a mapping failure the header
pointers will be invalidated and can result in a
TSO or other failure down the line. So, when the
remapping occurs force a retry thru the offload
calculation code. Thanks to Andrew Boyer for discovering
this and cooking up the fix!!
to calculate the outstanding descriptors that need to be
refreshed at any time, and use THAT in rxeof to determine
if refreshing needs to be done. Also change the local_timer
to simply fire off the appropriate interrupt rather than
schedule a tasklet, its simpler.
MFC in two weeks
been undergoing test for some weeks. This improves the RX
mbuf handling to avoid system hang due to depletion. Thanks
to all those who have been testing the code, and to Beezar
Liu for the design changes.
Next the igb driver is updated for similar RX changes, but
also to add new features support for our upcoming i350 family
of adapters.
MFC after a week
- this also includes virtualization support on these devices
Correct some vlan issues we were seeing in test, jumbo frames on vlans
did not work correctly, this was all due to confused logic around HW
filters, the new code should now work for all uses.
Important fix: when mbuf resources are depeleted, it was possible to
completely empty the RX ring, and then the RX engine would stall
forever. This is fixed by a flag being set whenever the refresh code
fails due to an mbuf shortage, also the local timer now makes sure
that all queues get an interrupt when it runs, the interrupt code
will then always call rxeof, and in that routine the first thing done
is now to check the refresh flag and call refresh_mbufs. This has been
verified to fix this type 'hang'. Similar code will follow in the other
drivers.
Finally, sync up shared code for the I350 support.
Thanks to everyone that has been reporting issues, and helping in the
debug/test process!!
- failure code in em_xmit got mangled along the way
and was not properly handling errors.
- local timer code had a leftover UNLOCK call that
should be removed.
MFC after 3 days
the size can be smaller than the constant when you are
doing HW TAGGING, and you still need to process this
packet in a normal way. I'm not sure where the notion
to just return came from, but its wrong.
MFC after: 3 days
Second, correct the discard/refresh_mbufs code to behave
more like igb, there have been panics due to discards and
this should fix them.
MFC after: 3 days
disable ASPM L0S and L1 LINK states on 82573, 82574,
and 82583. The theory is that this is behind certain
hangs being experienced by some customers.
Also included a small optimization in the rxeof routine
that was in my internal code.
Change the PBA size for pchlan, it was incorrect.
MFC after: 3 days
- Fixes from John Baldwin: vlan shadow tables made per/interface,
make vlan hw setup only happen when capability enabled, and
finally, make a tuneable interrupt rate. Thanks John!
- Tweaked watchdog handling to avoid any false positives, now
detection is in the TX clean path, with only the final check
and init happening in the local timer.
- limit queues to 8 for all devices, with 82576 or 82580 on
larger machines it can get greater than this, and it seems
mostly a resource waste to do so. Even 8 might be high but
it can be manually reduced.
- use 2k, 4k and now 9k clusters based on the MTU size.
- rework the igb_refresh_mbuf() code, its important to
make sure the descriptor is rewritten even when reusing
mbufs since writeback clobbers things.
MFC: in a few days, this delta needs to get to 8.2
ip and tcp pointers were not reset after some
pullups. In practice this led to an NFS mount
failure when using UDP reported by Kevin Lo,
thanks Kevin. Fix from yongari, thank you!
- Chasin down bogus watchdogs has led to an improved
design to this handling, the hang decision takes
place in the tx cleanup, with only a simple report
check in local_timer. Our tests have shown no false
watchdogs with this code.
- VLAN fixes from jhb, the shadow vfta should be per
interface, but as global it was not. Thanks John.
- Bug fixes in the support for new PCH2 hardware.
- Thanks for all the help and feedback on the driver,
changes to lem with be coming shortly as well.
- Sync shared code with Intel internal
- New client chipset support added
- em driver - fixes to 82574, limit queues to 1 but use MSIX
- em driver - large changes in TX checksum offload and tso
code, thanks to yongari.
- some small changes for watchdog issues.
- igb driver - local timer watchdog code was missing locking
this and a couple other watchdog related fixes.
- bug in rx discard found by Andrew Boyer, check for null pointer
MFC: a week
- Add a single sysctl procedure to all three drivers to read an arbitrary
register (the register is passed as arg2). Use it to replace existing
routines in igb(4) that used a separate routine for each register, and
to add support for missing stats in em(4) and lem(4).
- Move the 'rx_overruns' and 'watchdog_timeouts' stats out of the MAC stats
section as they are driver stats, not MAC counters.
- Simplify the code that creates per-queue stats in igb(4) to use a single
loop and remove duplicated code.
- Properly read all 64 bits of the 'good octets received/transmitted' in
em(4) and lem(4).
- Actually read the interrupt count registers in em(4), and drop the
'host to card' sysctl stats from em(4) as they are not implemented in
any of the hardware this driver supports.
- Restore several stats to em(4) that were lost in the earlier stats
conversion including per-queue stats.
- Export several MAC stats in em(4) that were exported in igb(4) but not
in em(4).
- Export stats in lem(4) using individual sysctls as in em(4) and igb(4).
Reviewed by: jfv
MFC after: 1 week
discrepencies from the igb version which was the target.
Change the message when neither MSI or MSIX are enabled
and a fallback to Legacy interrupts happen, the existing
message was confusing.
configuration function. For failed memory allocations, em(4)/lem(4)
called panic(9) which is not acceptable on production box.
igb(4)/ixgb(4)/ix(4) allocated the required memory in stack which
consumed 768 bytes of stack memory which looks too big.
To address these issues, allocate multicast array memory in device
attach time and make multicast configuration success under any
conditions. This change also removes the excessive use of memory in
stack.
Reviewed by: jfv
Just showing some buffer allocation error is more appropriate
action for drivers. This should fix occasional panic reported on
em(4) when driver encountered resource shortage.
Reviewed by: jfv
tail pointers of the tx and rx queues. We needed a SYSCTL_PROC
to correctly get the values at run time.
Submitted by: Andrew Boyer aboyer at averesystems.com
MFC after: 1 week
a packet has only a header in the first mbuf, the
checksum code will dereference a pointer into the
non-existing IP header. Do a check for the size and
pullup if needed. Thanks to Michael Tuexen for this
fix.
MFC: asap - should be in 8.1 IMHO
the core changes but left out the shared code, lol.
Well, and a couple fixes to the core... hopefully
this will all be complete now.
Happy happy joy joy :)
What this provides is support for the 'virtual function'
interface that a FreeBSD VM may be assigned from a host
like KVM on Linux, or newer versions of Xen with such
support.
When the guest is set up with the capability, a special
limited function 82576 PCI device is present in its virtual
PCI space, so with this driver installed in the guest that
device will be detected and function nearly like the bare
metal, as it were.
The interface is only allowed a single queue in this configuration
however initial performance tests have looked very good.
Enjoy!!
Remove unneeded rxtx handler, make que handler generic.
Do not allocate header mbufs in rx ring if not doing hdr split.
Release the lock in rxeof call to stack.
MFC for 8.1 asap
back in rxeof (I could see little point in taking it out),
and now release it before the stack entry.
Also, make it so the 82574 does not configure for multiqueue
when its not used in the stack.
unneeded for legacy hardware.
Also remove some TSO related cruft.
Add some watchdog_time setting that was missing, thanks
to Mikolaj Golub for pointing that out.
- code flow in handler could let interrupt be
reenabled when not wanted.
- change where the RX lock is taken to improve
performance.
- adapter->msix is true for MSI systems also,
it needs to explicitly test for 82574, good one :)
- add CRC stripping to the RX side, this was handled
by some obscure code in rxeof previously, its easier
to simply have the hardware strip it now.
- Add back an ALTQ change that slipped between the cracks
- Add an update to the watchdog_time in the xmit code, not
doing this in ixgbe caused problems, think its needed here
as well.
VLAN HWFILTER from being used by default, this breaks
stacked pseudo devices, and as it turns out, also breaks
virtual machines that happen to use VLANS (didn't know that
before :). Put the fix back into the em driver, and for good
measure add the same code to the igb driver where it should
have been anyway.
change the argument type to igb_rxeof() to the
correct type. Note, any users of POLLING must
be sure and set the number of queues to 1 for
things to work correctly.
em revision 7.0.0:
- Using driver devclass, seperate legacy (pre-pcie) code
into a seperate source file. This will at least help
protect against regression issues. It compiles along
with em, and is transparent to end use, devices in each
appear to be 'emX'. When using em in a modular form this
also allows the legacy stuff to be defined out.
- Add tx and rx rings as in igb, in the 82574 this becomes
actual multiqueue for the first time (2 queues) while in
other PCIE adapters its just make code cleaner.
- Add RX mbuf handling logic that matches igb, this will
eliminate packet drops due to temporary mbuf shortage.
igb revision 1.9.3:
- Following the ixgbe code, use a new approach in what
was called 'get_buf', the routine now has been made
independent of rxeof, it now does the update to the
engine TDT register, this design allows temporary
mbuf resources to become non-critical, not requiring
a packet to be discarded, instead it just returns and
does not increment the tail pointer.
- With the above change it was also unnecessary to keep
'spare' maps around, since we do not have the discard
issue.
- Performance tweaks and improvements to the code also.
MFC in a week
- introduce drbr_needs_enqueue that returns whether the interface/br needs
an enqueue operation: returns true if altq is enabled or there are
already packets in the ring (as we need to maintain packet order)
- update all drbr consumers
- fix drbr_flush
- avoid using the driver queue (IFQ_DRV_*) in the altq case as the
multiqueue consumer does not provide enough protection, serialize altq
interaction with the main queue lock
- make drbr_dequeue_cond work with altq
Discussed with: kmacy, yongari, jfv
MFC after: 4 weeks
lagg and vlan the vlan attach/detach event is not being
handed down to em, this caused some init code not to run,
and thus VLANs did not work. Ultimately having the event
get propagated would be nice, but for now the solution is
to have HWFILTER off by default, when this is the case
VLANs will work, ifconfig can be used to turn it on and
then get HW tag filtering.
igb now has a queue notion that has a single interrupt
with an RX/TX pair, this will reduce the total interrupts
seen on a system. Both em and igb have a new watchdog
method. igb has fixes from Pyun Yong-Hyeon that have
improved stability, thank you :)
I wish to MFC this for 7.3 asap, please test if able.
drivers. These add new hardware support, most importantly
the pch (i5 chipset) in the em driver. Also, both drivers
now have the simplified (and I hope improved) watchdog
code. The igb driver uses the new RX cleanup that I
first implemented in ixgbe.
em - version 6.9.24
igb - version 1.8.4
page fault panic on initialization due to a large
number of bounce pages being allocated. This is due
to the dma tag requiring page alignment on mbuf mapping.
This was removed some time back from the ixgbe driver
and is not needed here either.
Without this changeset there will be no way to prevent these NICs from
sending ARP, which is harmful in server farms that is configured as
"Direct Server Return" behind a load balancer.
A better fix would remove the whole hack completely but it would be
later than 8.0-RELEASE.
Reviewed by: jfv, yongari
Approved by: re (kib)
- When a vlan event occurs a check was not made that
the event was actually for the interface, thus resulting
in a panic. All three drivers have this vulnerability. Add
a check for this condition.
- Secondly, there was a duplicate buf_ring free in the em
driver resulting in a panic on unload. Remove.
Approved by: re
