Message ID | 1358160234-24996-1-git-send-email-amwang@redhat.com |
---|---|
State | Changes Requested, archived |
Delegated to: | David Miller |
Headers | show |
Mon, Jan 14, 2013 at 11:43:54AM CET, amwang@redhat.com wrote: >From: Cong Wang <amwang@redhat.com> > >This patch fixes the following warning: > >[ 72.013864] RTNL: assertion failed at net/core/dev.c (4955) >[ 72.017758] Pid: 668, comm: netpoll-prep-v6 Not tainted 3.8.0-rc1+ #474 >[ 72.019582] Call Trace: >[ 72.020295] [<ffffffff8176653d>] netdev_master_upper_dev_get+0x35/0x58 >[ 72.022545] [<ffffffff81784edd>] netpoll_setup+0x61/0x340 >[ 72.024846] [<ffffffff815d837e>] store_enabled+0x82/0xc3 >[ 72.027466] [<ffffffff815d7e51>] netconsole_target_attr_store+0x35/0x37 >[ 72.029348] [<ffffffff811c3479>] configfs_write_file+0xe2/0x10c >[ 72.030959] [<ffffffff8115d239>] vfs_write+0xaf/0xf6 >[ 72.032359] [<ffffffff81978a05>] ? sysret_check+0x22/0x5d >[ 72.033824] [<ffffffff8115d453>] sys_write+0x5c/0x84 >[ 72.035328] [<ffffffff819789d9>] system_call_fastpath+0x16/0x1b > >Just hold RCU read lock and call netdev_master_upper_dev_get_rcu(), >as suggested by Jiri. > >Cc: Jiri Pirko <jiri@resnulli.us> >Cc: David S. Miller <davem@davemloft.net> >Signed-off-by: Cong Wang <amwang@redhat.com> Reviewed-by: Jiri Pirko <jiri@resnulli.us> > >--- >diff --git a/net/core/netpoll.c b/net/core/netpoll.c >index 9f05067..5d1f856 100644 >--- a/net/core/netpoll.c >+++ b/net/core/netpoll.c >@@ -1055,11 +1055,14 @@ int netpoll_setup(struct netpoll *np) > return -ENODEV; > } > >- if (netdev_master_upper_dev_get(ndev)) { >+ rcu_read_lock(); >+ if (netdev_master_upper_dev_get_rcu(ndev)) { >+ rcu_read_unlock(); > np_err(np, "%s is a slave device, aborting\n", np->dev_name); > err = -EBUSY; > goto put; > } >+ rcu_read_unlock(); > > if (!netif_running(ndev)) { > unsigned long atmost, atleast; Thanks Amerigo. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, 2013-01-14 at 18:43 +0800, Cong Wang wrote: > From: Cong Wang <amwang@redhat.com> > > This patch fixes the following warning: > > [ 72.013864] RTNL: assertion failed at net/core/dev.c (4955) > [ 72.017758] Pid: 668, comm: netpoll-prep-v6 Not tainted 3.8.0-rc1+ #474 > [ 72.019582] Call Trace: > [ 72.020295] [<ffffffff8176653d>] netdev_master_upper_dev_get+0x35/0x58 > [ 72.022545] [<ffffffff81784edd>] netpoll_setup+0x61/0x340 > [ 72.024846] [<ffffffff815d837e>] store_enabled+0x82/0xc3 > [ 72.027466] [<ffffffff815d7e51>] netconsole_target_attr_store+0x35/0x37 > [ 72.029348] [<ffffffff811c3479>] configfs_write_file+0xe2/0x10c > [ 72.030959] [<ffffffff8115d239>] vfs_write+0xaf/0xf6 > [ 72.032359] [<ffffffff81978a05>] ? sysret_check+0x22/0x5d > [ 72.033824] [<ffffffff8115d453>] sys_write+0x5c/0x84 > [ 72.035328] [<ffffffff819789d9>] system_call_fastpath+0x16/0x1b > > Just hold RCU read lock and call netdev_master_upper_dev_get_rcu(), > as suggested by Jiri. > > Cc: Jiri Pirko <jiri@resnulli.us> > Cc: David S. Miller <davem@davemloft.net> > Signed-off-by: Cong Wang <amwang@redhat.com> > > --- > diff --git a/net/core/netpoll.c b/net/core/netpoll.c > index 9f05067..5d1f856 100644 > --- a/net/core/netpoll.c > +++ b/net/core/netpoll.c > @@ -1055,11 +1055,14 @@ int netpoll_setup(struct netpoll *np) > return -ENODEV; > } > > - if (netdev_master_upper_dev_get(ndev)) { > + rcu_read_lock(); > + if (netdev_master_upper_dev_get_rcu(ndev)) { > + rcu_read_unlock(); > np_err(np, "%s is a slave device, aborting\n", np->dev_name); > err = -EBUSY; > goto put; > } > + rcu_read_unlock(); > > if (!netif_running(ndev)) { > unsigned long atmost, atleast; > -- Strange, why dont we call netdev_master_upper_dev_get() instead ? -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, 2013-01-14 at 09:07 -0800, Eric Dumazet wrote: > Strange, why dont we call netdev_master_upper_dev_get() instead ? > > What I meant is : the result of this check might be of little use, if we don't hold any lock preventing another thread to change things behind us. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
From: Eric Dumazet <eric.dumazet@gmail.com> Date: Mon, 14 Jan 2013 09:09:56 -0800 > On Mon, 2013-01-14 at 09:07 -0800, Eric Dumazet wrote: > >> Strange, why dont we call netdev_master_upper_dev_get() instead ? >> >> > > What I meant is : the result of this check might be of little use, if we > don't hold any lock preventing another thread to change things behind > us. Agreed, this test is going to be racey. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, 2013-01-14 at 09:09 -0800, Eric Dumazet wrote: > On Mon, 2013-01-14 at 09:07 -0800, Eric Dumazet wrote: > > > Strange, why dont we call netdev_master_upper_dev_get() instead ? > > > > > > What I meant is : the result of this check might be of little use, if we > don't hold any lock preventing another thread to change things behind > us. > > Even if so, enslaving this device can still happen after we release the rtnl lock, unless we take this lock for the whole netpoll_setup(). Am I missing anything? -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/core/netpoll.c b/net/core/netpoll.c index 9f05067..5d1f856 100644 --- a/net/core/netpoll.c +++ b/net/core/netpoll.c @@ -1055,11 +1055,14 @@ int netpoll_setup(struct netpoll *np) return -ENODEV; } - if (netdev_master_upper_dev_get(ndev)) { + rcu_read_lock(); + if (netdev_master_upper_dev_get_rcu(ndev)) { + rcu_read_unlock(); np_err(np, "%s is a slave device, aborting\n", np->dev_name); err = -EBUSY; goto put; } + rcu_read_unlock(); if (!netif_running(ndev)) { unsigned long atmost, atleast;