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Revision 6e474083f3daf3a3546737f5d7d502ad12eb257c authored by Wei Xu on 01 December 2017, 10:10:36 UTC, committed by David S. Miller on 03 December 2017, 02:31:03 UTC 
vhost: fix skb leak in handle_rx()
 
Matthew found a roughly 40% tcp throughput regression with commit
c67df11f(vhost_net: try batch dequing from skb array) as discussed
in the following thread:
https://www.mail-archive.com/netdev@vger.kernel.org/msg187936.html

Eventually we figured out that it was a skb leak in handle_rx()
when sending packets to the VM. This usually happens when a guest
can not drain out vq as fast as vhost fills in, afterwards it sets
off the traffic jam and leaks skb(s) which occurs as no headcount
to send on the vq from vhost side.

This can be avoided by making sure we have got enough headcount
before actually consuming a skb from the batched rx array while
transmitting, which is simply done by moving checking the zero
headcount a bit ahead.

Signed-off-by: Wei Xu <wexu@redhat.com>
Reported-by: Matthew Rosato <mjrosato@linux.vnet.ibm.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
1 parent fa935ca
Raw File
Kconfig 
#
# STMicroelectonics LIS3LV02D and similar accelerometers
#

config SENSORS_LIS3_SPI
	tristate "STMicroeletronics LIS3LV02Dx three-axis digital accelerometer (SPI)"
	depends on !ACPI && SPI_MASTER && INPUT
	select SENSORS_LIS3LV02D
	default n
	help
	  This driver provides support for the LIS3LV02Dx accelerometer connected
	  via SPI. The accelerometer data is readable via
	  /sys/devices/platform/lis3lv02d.

	  This driver also provides an absolute input class device, allowing
	  the laptop to act as a pinball machine-esque joystick.

	  This driver can also be built as modules.  If so, the core module
	  will be called lis3lv02d and a specific module for the SPI transport
	  is called lis3lv02d_spi.

config SENSORS_LIS3_I2C
	tristate "STMicroeletronics LIS3LV02Dx three-axis digital accelerometer (I2C)"
	depends on I2C && INPUT
	select SENSORS_LIS3LV02D
	default n
	help
	  This driver provides support for the LIS3LV02Dx accelerometer connected
	  via I2C. The accelerometer data is readable via
	  /sys/devices/platform/lis3lv02d.

	  This driver also provides an absolute input class device, allowing
	  the device to act as a pinball machine-esque joystick.

	  This driver can also be built as modules.  If so, the core module
	  will be called lis3lv02d and a specific module for the I2C transport
	  is called lis3lv02d_i2c.
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