Date: Tue, 15 Jun 1999 20:09:47 +0200 From: Guido van Rooij <guido@gvr.org> To: Matthew Dillon <dillon@apollo.backplane.com>, Matthew Jacob <mjacob@feral.com> Cc: freebsd-hackers@FreeBSD.ORG, peter@FreeBSD.ORG Subject: Re: D'oh! Message-ID: <19990615200947.B3803@gvr.org> In-Reply-To: <199906151737.KAA19611@apollo.backplane.com>; from Matthew Dillon on Tue, Jun 15, 1999 at 10:37:18AM -0700 References: <Pine.BSF.4.05.9906151030470.5752-100000@semuta.feral.com> <199906151737.KAA19611@apollo.backplane.com>
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On Tue, Jun 15, 1999 at 10:37:18AM -0700, Matthew Dillon wrote:
>
> Sounds good to me! If someone on -hackers has easy access to the OpenBSD
> source, it would be nice if he could check whether the OpenBSD code
> has the same problem and notify the OpenBSD folks if it does.
they dont seem to have the nfs_node_hash_lock at all.
Our code in nfs_nget():
loop:
for (np = nhpp->lh_first; np != 0; np = np->n_hash.le_next) {
if (mntp != NFSTOV(np)->v_mount || np->n_fhsize != fhsize ||
bcmp((caddr_t)fhp, (caddr_t)np->n_fhp, fhsize))
continue;
vp = NFSTOV(np);
if (vget(vp, 1))
goto loop;
*npp = np;
return(0);
}
/*
* Obtain a lock to prevent a race condition if the getnewvnode()
* or MALLOC() below happens to block.
*/
if (nfs_node_hash_lock) {
while (nfs_node_hash_lock) {
nfs_node_hash_lock = -1;
tsleep(&nfs_node_hash_lock, PVM, "nfsngt", 0);
}
nfs_node_hash_lock = 1;
/*
* Do the MALLOC before the getnewvnode since doing so afterward
* might cause a bogus v_data pointer to get dereferenced
* elsewhere if MALLOC should block.
*/
MALLOC(np, struct nfsnode *, sizeof *np, M_NFSNODE, M_WAITOK);
error = getnewvnode(VT_NFS, mntp, nfsv2_vnodeop_p, &nvp);
Their code:
loop:
for (np = nhpp->lh_first; np != 0; np = np->n_hash.le_next) {
if (mntp != NFSTOV(np)->v_mount || np->n_fhsize != fhsize ||
bcmp((caddr_t)fhp, (caddr_t)np->n_fhp, fhsize))
continue;
vp = NFSTOV(np);
if (vget(vp, LK_EXCLUSIVE, p))
goto loop;
*npp = np;
return(0);
}
error = getnewvnode(VT_NFS, mntp, nfsv2_vnodeop_p, &nvp);
if (error) {
*npp = 0;
return (error);
}
vp = nvp;
MALLOC(np, struct nfsnode *, sizeof *np, M_NFSNODE, M_WAITOK);
I have not checked if they have fixed this otherwise though.
-Guido
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