[PATCH RFC] gianfar: Make polling safe with IRQs disabled

David Miller davem at davemloft.net
Sun Nov 8 20:05:33 EST 2009

From: Anton Vorontsov <avorontsov at ru.mvista.com>
Date: Thu, 5 Nov 2009 01:57:11 +0300

> When using KGDBoE, gianfar driver spits 'Interrupt problem' messages,
> which appears to be a legitimate warning, i.e. we may end up calling
> netif_receive_skb() or vlan_hwaccel_receive_skb() with IRQs disabled.
> This patch reworks the RX path so that if netpoll is enabled (the
> only case when the driver don't know from what context the polling
> may be called), we check whether IRQs are disabled, and if so we
> fall back to safe variants of skb receiving functions.
> Signed-off-by: Anton Vorontsov <avorontsov at ru.mvista.com>

This is bogus, I'll tell you why.

When you go into netif_receive_skb() we have a special check,
"if (netpoll_receive_skb(..." that takes care of all of the
details concerning doing a ->poll() from IRQ disabled context
via netpoll.

So this code you're adding should not be necessary.

Or, explain to me why no other driver needs special logic in their
->poll() handler like this and does not run into any kinds of netpoll
problems :-)

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