| Message ID | 1358242446-4273-1-git-send-email-amwang@redhat.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
From: Cong Wang <amwang@redhat.com> Date: Tue, 15 Jan 2013 17:34:06 +0800 > From: Cong Wang <amwang@redhat.com> > > v4: hold rtnl lock for the whole netpoll_setup() > v3: remove the comment > v2: use RCU read lock > > 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 > > In case of other races, hold rtnl lock for the entire netpoll_setup() function. > > Cc: Eric Dumazet <eric.dumazet@gmail.com> > Cc: Jiri Pirko <jiri@resnulli.us> > Cc: David S. Miller <davem@davemloft.net> > Signed-off-by: Cong Wang <amwang@redhat.com> Applied. -- 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 Tue, 2013-01-15 at 17:34 +0800, Cong Wang wrote: > From: Cong Wang <amwang@redhat.com> > > v4: hold rtnl lock for the whole netpoll_setup() > v3: remove the comment > v2: use RCU read lock > > 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 > > In case of other races, hold rtnl lock for the entire netpoll_setup() function. > > Cc: Eric Dumazet <eric.dumazet@gmail.com> > 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 ... > if (np->dev_name) > - ndev = dev_get_by_name(&init_net, np->dev_name); > + ndev = __dev_get_by_name(&init_net, np->dev_name); This change brings interesting bugs. All the "goto put;" are basically wrong, and the section waiting for the carrier and releasing/getting rtnl is buggy. Please revert this part. -- 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: Wed, 16 Jan 2013 17:24:45 -0800 >> if (np->dev_name) >> - ndev = dev_get_by_name(&init_net, np->dev_name); >> + ndev = __dev_get_by_name(&init_net, np->dev_name); ... > Please revert this part. You mean just revert that hunk above that made it use the non-refcounting version of dev_get_by_name()? -- 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 Wed, 2013-01-16 at 22:52 -0500, David Miller wrote: > From: Eric Dumazet <eric.dumazet@gmail.com> > Date: Wed, 16 Jan 2013 17:24:45 -0800 > > >> if (np->dev_name) > >> - ndev = dev_get_by_name(&init_net, np->dev_name); > >> + ndev = __dev_get_by_name(&init_net, np->dev_name); > ... > > Please revert this part. > > You mean just revert that hunk above that made it use the > non-refcounting version of dev_get_by_name()? But there is no reason to take both rtnl lock and RCU read lock, although that is fine. I think just adding dev_hold() is enough. -- 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..a5ad1c1 100644 --- a/net/core/netpoll.c +++ b/net/core/netpoll.c @@ -1048,11 +1048,13 @@ int netpoll_setup(struct netpoll *np) struct in_device *in_dev; int err; + rtnl_lock(); if (np->dev_name) - ndev = dev_get_by_name(&init_net, np->dev_name); + ndev = __dev_get_by_name(&init_net, np->dev_name); if (!ndev) { np_err(np, "%s doesn't exist, aborting\n", np->dev_name); - return -ENODEV; + err = -ENODEV; + goto unlock; } if (netdev_master_upper_dev_get(ndev)) { @@ -1066,15 +1068,14 @@ int netpoll_setup(struct netpoll *np) np_info(np, "device %s not up yet, forcing it\n", np->dev_name); - rtnl_lock(); err = dev_open(ndev); - rtnl_unlock(); if (err) { np_err(np, "failed to open %s\n", ndev->name); goto put; } + rtnl_unlock(); atleast = jiffies + HZ/10; atmost = jiffies + carrier_timeout * HZ; while (!netif_carrier_ok(ndev)) { @@ -1094,16 +1095,14 @@ int netpoll_setup(struct netpoll *np) np_notice(np, "carrier detect appears untrustworthy, waiting 4 seconds\n"); msleep(4000); } + rtnl_lock(); } if (!np->local_ip.ip) { if (!np->ipv6) { - rcu_read_lock(); - in_dev = __in_dev_get_rcu(ndev); - + in_dev = __in_dev_get_rtnl(ndev); if (!in_dev || !in_dev->ifa_list) { - rcu_read_unlock(); np_err(np, "no IP address for %s, aborting\n", np->dev_name); err = -EDESTADDRREQ; @@ -1111,14 +1110,12 @@ int netpoll_setup(struct netpoll *np) } np->local_ip.ip = in_dev->ifa_list->ifa_local; - rcu_read_unlock(); np_info(np, "local IP %pI4\n", &np->local_ip.ip); } else { #if IS_ENABLED(CONFIG_IPV6) struct inet6_dev *idev; err = -EDESTADDRREQ; - rcu_read_lock(); idev = __in6_dev_get(ndev); if (idev) { struct inet6_ifaddr *ifp; @@ -1133,7 +1130,6 @@ int netpoll_setup(struct netpoll *np) } read_unlock_bh(&idev->lock); } - rcu_read_unlock(); if (err) { np_err(np, "no IPv6 address for %s, aborting\n", np->dev_name); @@ -1151,17 +1147,17 @@ int netpoll_setup(struct netpoll *np) /* fill up the skb queue */ refill_skbs(); - rtnl_lock(); err = __netpoll_setup(np, ndev, GFP_KERNEL); - rtnl_unlock(); - if (err) goto put; + rtnl_unlock(); return 0; put: dev_put(ndev); +unlock: + rtnl_unlock(); return err; } EXPORT_SYMBOL(netpoll_setup);