Date: Fri, 18 Apr 2008 15:29:10 +0900 From: gnn@freebsd.org To: vijay singh <vijjus@rocketmail.com> Cc: freebsd-net@freebsd.org Subject: Re: Regarding if_alloc() Message-ID: <m2iqyfptft.wl%gnn@neville-neil.com> In-Reply-To: <490341.95478.qm@web33501.mail.mud.yahoo.com> References: <490341.95478.qm@web33501.mail.mud.yahoo.com>
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At Thu, 17 Apr 2008 18:35:23 -0700 (PDT),
vijay singh wrote:
>
> Hi all. How do we avoid a race in populating the ifindex_table? Id
> this is a TODO, as it seems from the code below, would it be
> acceptable if I wrote a patch and reused the ifnet_lock
> [IFNET_WLOCK, IFNET_WUNLOCK]?
>
It is almost always acceptable to submit a patch :-)
>
> if_alloc(u_char type)
> {
> struct ifnet *ifp;
>
> ifp = malloc(sizeof(struct ifnet), M_IFNET, M_WAITOK|M_ZERO);
>
> /*
> * Try to find an empty slot below if_index. If we fail, take
> * the next slot.
> *
> * XXX: should be locked!
> */
> for (ifp->if_index = 1; ifp->if_index <= if_index; ifp->if_index++) {
> if (ifnet_byindex(ifp->if_index) == NULL)
> break;
> }
>
>
There are still parts of the network device infrastructure that need
some locking, and it would seem that this is one of them. I know
Brooks Davis was also looking at this stuff so he may comment as well.
Best,
George
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