Re: if_start running deferred for Giant


On Mon, 31 Dec 2007, Tofig Suleymanov wrote:

xxxxxx kernel: ib0: if_start running deferred for Giant

I am not sure what does this exactly mean.

Any help would be appreciated.

This occurs when a network device driver has declared itself IFF_NEEDSGIANT -- that is, has declared that it requires the Giant lock in order to operate. As this is considered an undesirable state of affairs for a device driver, a warning is printed. However, in the case of a USB device driver, it is currently required as the USB framework is not MPSAFE, so requires Giant.

Thanks for clarification. Does it mean that I can ignore this notice when dealing with USB framework ?

For now, yes. When, at some point, the USB framework is MPSAFE, we'll need to remove IFF_NEEDSGIANT, and I'd make sure that your device driver is as ready as it can be to operate Giant-free once that's done.

Robert N M Watson
Computer Laboratory
University of Cambridge
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