From: Johannes Berg Subject: Re: [PATCH 03/10] mac80211: Use rcu_barrier() on unload. Date: Tue, 23 Jun 2009 17:15:55 +0200 Message-ID: <1245770155.21314.38.camel@johannes.local> References: <20090623150330.22490.87327.stgit@localhost> <20090623150409.22490.99106.stgit@localhost> Mime-Version: 1.0 Content-Type: multipart/signed; micalg="pgp-sha1"; protocol="application/pgp-signature"; boundary="=-4pWj/zfZZMHnV2anu3HO" Cc: "David S. Miller" , "Paul E. McKenney" , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, dougthompson@xmission.com, bluesmoke-devel@lists.sourceforge.net, axboe@kernel.dk, Patrick McHardy , christine.caulfield@googlemail.com, Trond.Myklebust@netapp.com, linux-wireless@vger.kernel.org, yoshfuji@linux-ipv6.org, shemminger@linux-foundation.org, linux-nfs@vger.kernel.org, bfields@fieldses.org, neilb@suse.de, linux-ext4@vger.kernel.org, tytso@mit.edu, adilger@sun.com, netfilter-devel@vger.kernel.org To: Jesper Dangaard Brouer Return-path: In-Reply-To: <20090623150409.22490.99106.stgit@localhost> Sender: netdev-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org --=-4pWj/zfZZMHnV2anu3HO Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Tue, 2009-06-23 at 17:04 +0200, Jesper Dangaard Brouer wrote: > The mac80211 module uses rcu_call() thus it should use rcu_barrier() > on module unload. >=20 > I'm having a hardtime verifying that no more call_rcu() callbacks can > be schedules in the module unload path. Could a maintainer please > look into this? >=20 > Signed-off-by: Jesper Dangaard Brouer > --- >=20 > net/mac80211/main.c | 2 ++ > 1 files changed, 2 insertions(+), 0 deletions(-) >=20 > diff --git a/net/mac80211/main.c b/net/mac80211/main.c > index 092a017..e9f70ce 100644 > --- a/net/mac80211/main.c > +++ b/net/mac80211/main.c > @@ -1100,6 +1100,8 @@ static void __exit ieee80211_exit(void) > ieee80211s_stop(); > =20 > ieee80211_debugfs_netdev_exit(); > + > + rcu_barrier(); /* Wait for completion of call_rcu()'s */ > } I don't think this is correct at all -- note that call_rcu() is done in some of the mesh code, so I would think you need to do this in ieee80211_stop() since the call_rcu() code requires the interface to still be around. And when it's stopped everything should be idle. I can fix it later, but I'm deep in some other stuff right now. johannes --=-4pWj/zfZZMHnV2anu3HO Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- iQIcBAABAgAGBQJKQPGoAAoJEODzc/N7+QmazPkP/juLnaNnvhYosQYGZ2G0lzA2 O1JQP2Hp4TpyxHI8dGDHq+gO1BCAbKQp7zA/PKH3u346AYgp3uvedhNAWqzvdRPS TGO/cY0ZmgUJbzk/v4rB9SinMsuYiL7DgSaK11Fv0KZBqcKxMLO8K39yOdn/TAfi xGEqIUkDFUJvxuXEINxt2OPInpzSHEDYQCf3EU4TkZ9hziahx0Gj8dNzzJcp+zSu 3EGnm8H7+WkT7qWyS7ur7C9JFp/7ySsN2cW6DGs594vKSHM6kHOrtjIH2eOc3pQM uqr5YnTefT88ZvuqMSSmAi0BzmlH77atuegwUBXpAtKb1cdJG7R+h2URNWrC5APm YDv3w7UvmyDXcRotygdsug6gstMmAfoIgzfCPoJYFGJ7ZYmuyUejH7QMlzsuvc22 7fvWQZPKqeAvOhMn7/kdTZEA2KMntRvcEf+QX8PoeEn0Zpw/zY42FBNXG7d+RQf6 SqLzdV/DQGzPbtzXVXPYbq9vWCF98887mItGXhK5Q3ah/Qn330i3TRWLoXhGMbTM TScPV5FZDkBOL8ohzQVdJ/CDjwDQTYE3sqb0yJ9Qnmr+M0JwxPXFiKemRtywSntf fJVDsKgVSjW6/XWZRgGGHGXFWV1kTdumKAvKZDbW5TzTCv2VqUojw8tiNp3yplYR 7jBVLeH6bZqk/962Kn/0 =4r0R -----END PGP SIGNATURE----- --=-4pWj/zfZZMHnV2anu3HO--