Subject: Re: [PATCH v2] net: Introduce realloc_netdev_mq()

From: Eric Dumazet <[email-masked]>
Date: Thu, 03 Dec 2009 16:17:43 +0100

Jarek Poplawski a écrit :
> Take 2 (with forgotten headers, sorry).

Very nice, thanks !

> Here is a proposal of netdev api change. I hope Michael finds time
> to try if this can be really useful for drivers.
> 
> Thanks,
> Jarek P.
> ---------------> (take 2)
> 
> This patch separates allocation of TX subqueues from alloc_netdev_mq()
> to realloc_netdev_mq() to allow for resizing like in this example:
> 
> some_nic_probe()
> {
> 	...
> 	dev = alloc_etherdev_mq(sizeof(*bp), 1)
> 	...
> 	if (MSI-X_available && device_supports_MSI-X_and_multiqueue)
> 		realloc_netdev_mq(dev, TX_MAX_RINGS)
> 	register_netdev(dev)
> 	...
> }
> 

Or the reverse :

ie, the device first allocate its max possible tx rings

dev = alloc_etherdev_mq(sizeof(*bp), 128)

then, later, try to reduce it, when knowing exact tx count.

if (realloc_netdev_mq(dev, real_queues))
	dev->real_num_tx_queues = real_queues;

In this case the memory error is not fatal.