From: "Paul E. McKenney" <paulmck@kernel.org>
To: Joel Fernandes <joel@joelfernandes.org>
Cc: linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org,
anna.schumaker@netapp.com, rcu@vger.kernel.org,
linux-kernel-mentees@lists.linuxfoundation.org,
trond.myklebust@hammerspace.com
Subject: Re: [Linux-kernel-mentees] [PATCH 2/2] fs: nfs: dir.c: Fix sparse error
Date: Fri, 6 Dec 2019 08:12:01 -0800 [thread overview]
Message-ID: <20191206161201.GF2889@paulmck-ThinkPad-P72> (raw)
In-Reply-To: <20191206160002.GB15547@google.com>
On Fri, Dec 06, 2019 at 11:00:02AM -0500, Joel Fernandes wrote:
> +Paul, here is the dependent patch for the list_prev_rcu() patch Madhuparna
> posted.
Got it, thank you!
And however this turns out, it does illustrate the value of the sparse
address-space checks!
Thanx, Paul
> On Fri, Dec 06, 2019 at 08:46:40PM +0530, madhuparnabhowmik04@gmail.com wrote:
> > From: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>
> >
> > This patch fixes the following errors:
> > fs/nfs/dir.c:2353:14: error: incompatible types in comparison expression (different address spaces):
> > fs/nfs/dir.c:2353:14: struct list_head [noderef] <asn:4> *
> > fs/nfs/dir.c:2353:14: struct list_head *
> >
> > caused due to directly accessing the prev pointer of
> > a RCU protected list.
> > Accessing the pointer using the macro list_prev_rcu() fixes this error.
> >
> > Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>
> > ---
> > fs/nfs/dir.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
> > index e180033e35cf..2035254cc283 100644
> > --- a/fs/nfs/dir.c
> > +++ b/fs/nfs/dir.c
> > @@ -2350,7 +2350,7 @@ static int nfs_access_get_cached_rcu(struct inode *inode, const struct cred *cre
> > rcu_read_lock();
> > if (nfsi->cache_validity & NFS_INO_INVALID_ACCESS)
> > goto out;
> > - lh = rcu_dereference(nfsi->access_cache_entry_lru.prev);
> > + lh = rcu_dereference(list_prev_rcu(&nfsi->access_cache_entry_lru));
> > cache = list_entry(lh, struct nfs_access_entry, lru);
> > if (lh == &nfsi->access_cache_entry_lru ||
> > cred != cache->cred)
> > --
> > 2.17.1
> >
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next prev parent reply other threads:[~2019-12-06 16:12 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-06 15:16 [Linux-kernel-mentees] [PATCH 2/2] fs: nfs: dir.c: Fix sparse error madhuparnabhowmik04
2019-12-06 16:00 ` Joel Fernandes
2019-12-06 16:12 ` Paul E. McKenney [this message]
2019-12-06 16:02 ` Paul E. McKenney
2019-12-06 17:52 ` Trond Myklebust
2019-12-06 18:24 ` Paul E. McKenney
2019-12-06 18:28 ` Trond Myklebust
2019-12-06 18:45 ` Paul E. McKenney
2019-12-12 21:55 ` Joel Fernandes
2019-12-13 1:16 ` Paul E. McKenney
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