[dpdk-dev] [PATCH] The VMXNET3 PMD can't receive packet suddenly after a lot of traffic coming in. The root cause is due to mbuf allocation fail in vmxnet3_post_rx_bufs() and there is no error handling when it is called from vmxnet3_recv_pkts(). Th...

[Stephen Hemminger]

On Thu, 23 Jul 2015 07:31:01 +0000
Vithal S Mohare <vmohare at arubanetworks.com> wrote:

> +    /* VMXNET3
> +     * In the above loop, vmxnet3_post_rx_bufs would fai if all the mbufs 
> currently allocated.
> +     * In such scenarios where hw device hasn't left with any of 'rx' 
> descriptors, packets from
> +     * network will not be 'DMA'd to driver.  While the only way to refresh 
> 'rxd' back to hw is
> +     * though above i.e. when packet is received from hw.  So, there is 
> potential dead-lock.
> +     *
> +     * Now, to break the deadlock, vmxnet3_post_rx_bufs() is triggered below 
> when the poll 
> +     * goes empty 'rcd'.  vmxnet3_post_rx_bufs() is no-op if all the 
> descriptors are allocated
> +     * in hw
> +     */

This is the kind of thing which should be in the git change log
description not the code. Comments like this are too wordy and get out
of date.