From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: [PATCH v2] net: Introduce realloc_netdev_mq()
Date: Thu, 03 Dec 2009 16:17:43 +0100
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Cc: David Miller <davem@davemloft.net>, mchan@broadcom.com,
	kaber@trash.net, netdev@vger.kernel.org
To: Jarek Poplawski <jarkao2@gmail.com>
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Jarek Poplawski a =E9crit :
> 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.
>=20
> Thanks,
> Jarek P.
> ---------------> (take 2)
>=20
> This patch separates allocation of TX subqueues from alloc_netdev_mq(=
)
> to realloc_netdev_mq() to allow for resizing like in this example:
>=20
> some_nic_probe()
> {
> 	...
> 	dev =3D 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)
> 	...
> }
>=20

Or the reverse :

ie, the device first allocate its max possible tx rings

dev =3D 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 =3D real_queues;

In this case the memory error is not fatal.