if_start running deferred for Giant

Tofig Suleymanov tofig at freebsd.az
Sun Dec 30 23:09:01 PST 2007


On 12/31/07, Robert Watson <rwatson at freebsd.org> wrote:
>
> 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
>

Now it is clear to me.

Thanks for your help.


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