Date: Mon, 23 Jan 2006 15:35:57 -0500 From: John Baldwin <jhb@freebsd.org> To: Tom Rhodes <trhodes@freebsd.org> Cc: cvs-src@freebsd.org, src-committers@freebsd.org, cvs-all@freebsd.org Subject: Re: cvs commit: src/sys/nfsserver nfs_serv.c Message-ID: <200601231535.59259.jhb@freebsd.org> In-Reply-To: <20060123150619.63e41bcd.trhodes@FreeBSD.org> References: <200601211210.k0LCAXYl069896@repoman.freebsd.org> <200601231459.25281.jhb@freebsd.org> <20060123150619.63e41bcd.trhodes@FreeBSD.org>
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On Monday 23 January 2006 15:06, Tom Rhodes wrote:
> On Mon, 23 Jan 2006 14:59:22 -0500
>
> John Baldwin <jhb@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@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?
--
John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve" = http://www.FreeBSD.org
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