cvs commit: src/sys/nfsserver nfs_serv.c

[Tom Rhodes]

On Mon, 23 Jan 2006 15:35:57 -0500
John Baldwin <jhb at freebsd.org> wrote:

> On Monday 23 January 2006 15:06, Tom Rhodes wrote:
> > On Mon, 23 Jan 2006 14:59:22 -0500
> >
> > John Baldwin <jhb at freebsd.org> wrote:
> > > On Monday 23 January 2006 14:28, Tom Rhodes wrote:
> > > > On Mon, 23 Jan 2006 13:56:16 -0500
> > > >
> > > > John Baldwin <jhb at FreeBSD.org> wrote:
> > > > > On Saturday 21 January 2006 07:10, Tom Rhodes wrote:
> > > > > > trhodes     2006-01-21 12:10:33 UTC
> > > > > >
> > > > > >   FreeBSD src repository
> > > > > >
> > > > > >   Modified files:
> > > > > >     sys/nfsserver        nfs_serv.c
> > > > > >   Log:
> > > > > >   Remove some dead code.
> > > > > >
> > > > > >   Found with:     Coverity Prevent(tm)
> > > > >
> > > > > Are you going to revert this change given the replies?
> > > >
> > > > Oh, I didn't interpret the comments as "this is wrong please
> > > > back it out."  I just seen replies, both public and private,
> > > > complaining about the indentation.  They went like:
> > > >
> > > > stefanf: "Are you sure this is correct?"
> > >
> > > When someone says this, you generally should be able to reply with either
> > > "Yes, because of X, Y, and Z", or "oops, I guess not, I'll back it out"
> >
> > I did reply, but forgot to CC: the cvs lists.  There was just
> > no bothering to follow up since I figured the discussion died,
> > since stefan never followed up.
> >
> > I'll find the reply and push it off.
> >
> > > >   rwatson: "code is a mess in NFS"
> > > >
> > > > ru: quoting the code "bad indentation"
> > > > njl quoting the code "bad indentation"
> > > >
> > > > rees (NFSv4 guy): "looks fine to me"
> > > >
> > > > If you, or anyone else for that matter actually wants it
> > > > reverted, I'll do that.  I'm not in the mood to argue
> > > > with people today, or ever.  :)
> > >
> > > <quote from="stefanf">
> > > Hm, are you sure this change is correct?  Apparently Coverity thinks
> > > that dirp is always 0 at this point, yes?  Looking at nfs_namei() I
> > > don't believe that.
> > > </quote>
> > >
> > > Note the "I don't believe that" part.
> > >
> > > <quote from="Peter Jeremy">
> > > I'll put my $0.02 in and agree with Stefan Farfeleder.  (Luckily, in
> > > this case, the notorious NFS macros are not involved).  The comments
> > > on nfs_namei() state that dirp can be returned not-NULL even if an
> > > error occurs and a check of the code paths in nfs_namei() indicates
> > > that this is correct.  Can you please re-evaluate your change.
> > >
> > > If (as I suspect), this is actually an incorrect report from Coverity,
> > > we should probably report it back to them to investigate.
> > > </quote>
> > >
> > > Please either offer explanations to address the concerns raised or back
> > > it out.
> >
> > ---------------------------------------------------------------
> >
> > > Hm, are you sure this change is correct?  Apparently Coverity thinks
> > > that dirp is always 0 at this point, yes?  Looking at nfs_namei() I
> > > don't believe that.  Also the comment above this is now stale and the
> > > code inside 'if (error)' not indented properly.
> >
> > Yes, this change should be correct.  dirp is always 0 except for
> > one part (which you mention above) and is used/tested elsewhere
> > for that reason.  njl and ru have already got me on the stale
> > comment and indention.  Jim Reese (NFSv4 guy) also feels that
> > this commit is "good."  So I got post-commit review.  ;)
> >
> > But I'll definitely agree with rwatson, the nfs code is really
> > scary.  :)
> > --------------------------------------------------------------
> 
> Hmm, what do you mean by "one part"?  For example, in nfs_namei() you can have 
> dirp != NULL in the following error cases (look for BEWM):
> 
> int
> nfs_namei(struct nameidata *ndp, fhandle_t *fhp, int len,
>     struct nfssvc_sock *slp, struct sockaddr *nam, struct mbuf **mdp,
>     caddr_t *dposp, struct vnode **retdirp, int v3, struct vattr *retdirattrp,
>     int *retdirattr_retp, struct thread *td, int pubflag)
> {
> 	...
> 
> 	*retdirp = NULL;
> 
> 	...
> 
> 	/*
> 	 * Set return directory.  Reference to dp is implicitly transfered
> 	 * to the returned pointer
> 	 */
> 	*retdirp = dp;
> 
> 	...
> 	if (pubflag) {
> 		...
> 		if ((unsigned char)*fromcp >= WEBNFS_SPECCHAR_START) {
> 			switch ((unsigned char)*fromcp) {
> 			...
> 			default:
> 				error = EIO;
> 				uma_zfree(namei_zone, cp);
> 				goto out;     <=== BEWM!!!!
> 			}
> 		}
> 		...
> 		while (*fromcp != '\0') {
> 			if (*fromcp == WEBNFS_ESC_CHAR) {
> 				if (fromcp[1] != '\0' && fromcp[2] != '\0') {
> 					...
> 				} else {
> 					error = ENOENT;
> 					uma_zfree(namei_zone, cp);
> 					goto out;  <=== BEWM!!!!
> 				}
> 			...
> 		}
> 	...
> 	for (;;) {
> 		...
> 		error = lookup(ndp);
> 		if (error)
> 			break;  <=== BEWM!!!
> 		...
> 		error = VOP_READLINK(ndp->ni_vp, &auio, cnp->cn_cred);
> 		if (error) {
> 			...
> 			vrele(ndp->ni_dvp);
> 			vput(ndp->ni_vp);
> 			break;  <<< BEWM!!!!
> 		}
> 		...
> 	}
> 	...
> out:
> 	...
> }
> 
> Won't your changes now be leaking a vnode reference in those cases?

Ack, put me in my place.  You're right, my bad, I'll back
it out now.  Sorry for the churn.

-- 
Tom Rhodes