Jeff Layton wrote: > On Mon, 9 Jun 2008 14:39:23 -0400 > "J. Bruce Fields" <bfields@xxxxxxxxxxxx> wrote: > > >> On Mon, Jun 09, 2008 at 09:19:48AM -0400, Jeff Layton wrote: >> >>> On Mon, 9 Jun 2008 09:08:30 -0400 >>> "J. Bruce Fields" <bfields@xxxxxxxxxxxx> wrote: >>> >>> >>>> On Fri, Jun 06, 2008 at 03:49:48PM -0400, Jeff Layton wrote: >>>> >>>>> On Fri, 6 Jun 2008 14:11:16 -0400 >>>>> Jeff Layton <jlayton@xxxxxxxxxx> wrote: >>>>> >>>>> >>>>>> On Fri, 6 Jun 2008 13:24:31 -0400 >>>>>> "J. Bruce Fields" <bfields@xxxxxxxxxxxx> wrote: >>>>>> >>>>>> >>>>> ... >>>>> >>>>>>> How does the module refcounting work after this patch? >>>>>>> >>>>>>> --b. >>>>>>> >>>>>>> >>>>>> I think I've goofed this part, actually. I was thinking that we didn't >>>>>> need to bump the refcount here, and that the kernel would realize that >>>>>> nfsd() hadn't returned and would prevent unloading until it had. This >>>>>> doesn't seem to be the case. I'll need to go back and add refcounting >>>>>> back in. >>>>>> >>>>>> >>>>> Here's a respun patch that adds back in the module refcounts and also >>>>> removes the unneeded "err = 0;" at the bottom of the loop. Thoughts? >>>>> >>>> Looks good to me. I'll apply all 5 (with this version of #4) if noone >>>> catches something else. >>>> >>>> --b. >>>> >>>> >>> Sounds good. My only concern here is whether moving the __module_get >>> from the RPC layer to nfsd() itself is OK. >>> >> Oh, I see, I missed that. >> >> >>> I *think* it is since the >>> nfsctl and /proc/fs/nfsd routines are all part of the nfsd module, so >>> we're guaranteed to have a reference there anyway, but if there are >>> potential races then we may want to go back to the old way. >>> >> The vfs should take care that e.g. it gets a reference on the module >> before creating an open file for the nfsd filesystem. Yes, but indirectly; I believe the module refcount belongs to the nfsd filesystem super_block, and having an open file on that filesystem keeps a vfsmount refcount which keeps the super_block refcount which keeps the module refcount. >> But it don't see >> how anything can guarantee that the __module_get() in the new nfsd >> thread completes before whoever called svc_set_num_threads() returns and >> drops their reference. >> >> So, yeah, I think it's not right. >> >> Agreed. > > Ok, that makes sense. I'll need to respin the set then since we'll need > the sv_module field in the svc_serv struct after all. Let me do that > and get back to you... > > Bother, I think that's right. -- Greg Banks, P.Engineer, SGI Australian Software Group. The cake is *not* a lie. I don't speak for SGI. -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
