Re: CVS commit: src/sys/kern

[Iain Hibbert <plunky%rya-online.net@localhost>]

On Thu, 16 Oct 2008, Andrew Doran wrote:

> On Sun, Oct 12, 2008 at 09:26:50AM +0000, Iain Hibbert wrote:
>
> > fix problem pointed out by ad where sockopt may end up sleeping
> > inappropriately with the socket lock held.
>
> Are you sure that enough space is always be available for sockopt_set()?
> If not, legitimate operations will be failed if the system is paging.

I'm not sure if I understand the question (context) exactly, but I think
the answer is that yes, sockopt_set() may fail due to lack of memory (uses
KM_NOSLEEP if allocation is required) but ENOMEM will be returned in that
case. It is of course up to the caller to make sure the return code is
checked and handle it properly (I believe all instances do)

If you need to use sockopt_set() in a context where memory allocation may
be required and you don't want to consider failure, then the sockopt
structure can be initialised in a better context with an appropriate
memory buffer using sockopt_init() which may sleep.

does this need clarifying in sockopt(9) ?

If you are referring to userland, then it is true that getsockopt(2) can
fail for lack of memory but it always could, if mbufs were somehow
exhausted

iain