Hi Greg,
this is the series I sent a few months ago that David has already
backported to 3.13-stable, and that did not apply well to 3.10. As
agreed with David he I've now handled the 3.10-stable one myself,
and rebased the patches on top of 3.10.51.
For better tracking I'm re-iterating here the issues these patches fix :
- driver lockup when reading stats while sending traffic from multiple
CPUs : this obviously only happens on SMP and is the result of missing
locking on the driver. The problem was present since the introduction
of the driver in 3.8. The first patch performs some changes that are
needed for the second one which actually fixes the issue by using
per-cpu counters. It could make sense to backport this to the relevant
stable versions.
- mvneta_tx_timeout calls various functions to reset the NIC, and these
functions sleep, which is not allowed here, resulting in a panic.
Better completely disable this Tx timeout handler for now since it is
never called. The problem was encountered while developing some new
features, it's uncertain whether it's possible to reproduce it with
regular usage, so maybe a backport to stable is not needed.
- replace the Tx timer with a real Tx IRQ. As first reported by Arnaud
Ebalard and explained by Eric Dumazet, there is no way this driver
can work correctly if it uses a timer to recycle the Tx descriptors.
If too many packets are sent at once, the driver quickly ends up with
no descriptors (which happens twice as easily in GSO) and has to wait
10ms for recycling its descriptors and being able to send again. Eric
has worked around this in the core GSO code. But still when routing
traffic or sending UDP packets, the limitation is very visible. Using
Tx IRQs allows Tx descriptors to be recycled when sent. The coalesce
value is still configurable using ethtool. This fix turns the UDP
send bitrate from 134 Mbps to 987 Mbps (ie: line rate). It's made of
two patches, one to add the relevant bits from the original Marvell's
driver, and another one to implement the change. I don't know if it
should be backported to stable, as the bug only causes poor performance.
Thanks,
Willy
---
willy tarreau (5):
net: mvneta: increase the 64-bit rx/tx stats out of the hot path
net: mvneta: use per_cpu stats to fix an SMP lock up
net: mvneta: do not schedule in mvneta_tx_timeout
net: mvneta: add missing bit descriptions for interrupt masks and
causes
net: mvneta: replace Tx timer with a real interrupt
drivers/net/ethernet/marvell/mvneta.c | 206 ++++++++++++++++++----------------
1 file changed, 108 insertions(+), 98 deletions(-)
--
1.7.12.2.21.g234cd45.dirty
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