net: ena: fix theoretical Rx hang on low memory systems

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For the rare case where the device runs out of free rx buffer
descriptors (in case of pressure on kernel  memory),
and the napi handler continuously fail to refill new Rx descriptors
until device rx queue totally runs out of all free rx buffers
to post incoming packet, leading to a deadlock:
* The device won't send interrupts since all the new
Rx packets will be dropped.
* The napi handler won't try to allocate new Rx descriptors
since allocation is part of NAPI that's not being invoked any more

The fix involves detecting this scenario and rescheduling NAPI
(to refill buffers) by the keepalive/watchdog task.

Fixes: 1738cd3ed3 ("Add a driver for Amazon Elastic Network Adapters (ENA)")
Signed-off-by: Netanel Belgazal <netanel@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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Netanel Belgazal 2017-06-11 15:42:48 +03:00 • committed by David S. Miller

parent 0857d92f71

commit a3af7c18cf

3 changed files with 58 additions and 0 deletions

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1

drivers/net/ethernet/amazon/ena/ena_ethtool.c

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55

drivers/net/ethernet/amazon/ena/ena_netdev.c

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2

drivers/net/ethernet/amazon/ena/ena_netdev.h

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