2006-12-20 03:46:05

by Benjamin Herrenschmidt

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Subject: netif_poll_enable() & barrier

Hi !

I stumbled accross what might be a bug on out of order architecture:

netif_poll_enable() only does a clear_bit(). However,
netif_poll_disable/enable pairs are often used as simili-spinlocks.

(netif_poll_enable() has pretty much spin_lock semantics except that it
schedules instead of looping).

Thus, shouldn't netif_poll_disable() do an smp_wmb(); before clearing
the bit to make sure that any stores done within the poll-disabled
section are properly visible to the rest of the system before clearing
the bit ?

Cheers,
Ben.