On Fri, Aug 28, 2015 at 3:05 PM, Nikolay Aleksandrov
<ra...@blackwall.org> wrote:
>
> From: Nikolay Aleksandrov <niko...@cumulusnetworks.com>
>
> The problem is rcu_read_unlock_bh() which triggers a warning when irqs are
> disabled. ndo_poll_controller should run with irqs disabled always so we
> can drop the rcu_read_lock_bh.
>
> [ 98.502922] bond0: making interface eth1 the new active one
> [ 98.503039] ------------[ cut here ]------------
> [ 98.503039] WARNING: CPU: 0 PID: 1744 at kernel/softirq.c:150
> __local_bh_enable_ip+0x96/0xc0()
> [ 98.503039] Modules linked in: bonding(OE) rpcsec_gss_krb5 nfsv4
> dns_resolver nfs fscache netconsole ppdev joydev parport_pc serio_raw parport
> i2c_piix4 video acpi_cpufreq nfsd auth_rpcgss nfs_acl lockd grace sunrpc
> virtio_net e1000 ata_generic pcnet32 mii virtio_pci virtio_ring virtio
> pata_acpi
> [ 98.503039] CPU: 0 PID: 1744 Comm: ifenslave Tainted: G OE
> 4.2.0-rc7+ #56
> [ 98.503039] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS
> VirtualBox 12/01/2006
> [ 98.503039] 0000000000000000 00000000e96ba230 ffff880020c236b8
> ffffffff8183f105
> [ 98.503039] 0000000000000000 0000000000000000 ffff880020c236f8
> ffffffff810a9496
> [ 98.503039] ffff88002ea99e08 0000000000000200 ffffffffa02a8e06
> ffff88002ea99e08
> [ 98.503039] Call Trace:
> [ 98.503039] [<ffffffff8183f105>] dump_stack+0x4c/0x65
> [ 98.503039] [<ffffffff810a9496>] warn_slowpath_common+0x86/0xc0
> [ 98.503039] [<ffffffffa02a8e06>] ? bond_poll_controller+0x146/0x250
> [bonding]
> [ 98.503039] [<ffffffff810a95ca>] warn_slowpath_null+0x1a/0x20
> [ 98.503039] [<ffffffff810ae376>] __local_bh_enable_ip+0x96/0xc0
> [ 98.503039] [<ffffffffa02a8e2f>] bond_poll_controller+0x16f/0x250
> [bonding]
> [ 98.503039] [<ffffffffa02a8cf3>] ? bond_poll_controller+0x33/0x250
> [bonding]
> [ 98.503039] [<ffffffff810feaed>] ? trace_hardirqs_off+0xd/0x10
> [ 98.503039] [<ffffffff81848afb>] ? _raw_spin_unlock_irqrestore+0x5b/0x60
> [ 98.503039] [<ffffffff816ec48e>] netpoll_poll_dev+0x6e/0x350
> [ 98.503039] [<ffffffff816eb977>] ? netpoll_start_xmit+0x137/0x1d0
> [ 98.503039] [<ffffffff816b2e8b>] ? __alloc_skb+0x5b/0x210
> [ 98.503039] [<ffffffff816ec89d>] netpoll_send_skb_on_dev+0x12d/0x2a0
> [ 98.503039] [<ffffffff816eccde>] netpoll_send_udp+0x2ce/0x430
> [ 98.503039] [<ffffffffa0190850>] write_msg+0xb0/0xf0 [netconsole]
> [ 98.503039] [<ffffffff81116b63>]
> call_console_drivers.constprop.25+0x133/0x260
> [ 98.503039] [<ffffffff81117934>] console_unlock+0x2f4/0x580
> [ 98.503039] [<ffffffff81117ea5>] ? vprintk_emit+0x2e5/0x630
> [ 98.503039] [<ffffffff81117ee5>] vprintk_emit+0x325/0x630
> [ 98.503039] [<ffffffff81118379>] vprintk_default+0x29/0x40
> [ 98.503039] [<ffffffff8183de4f>] printk+0x55/0x6b
> [ 98.503039] [<ffffffff816c754c>] __netdev_printk+0x16c/0x260
> [ 98.503039] [<ffffffff816c7a12>] netdev_info+0x62/0x80
> [ 98.503039] [<ffffffffa02ab464>] bond_change_active_slave+0x134/0x6a0
> [bonding]
> [ 98.503039] [<ffffffffa02aba95>] bond_select_active_slave+0xc5/0x310
> [bonding]
> [ 98.503039] [<ffffffffa02aeb78>] bond_enslave+0x1088/0x10c0 [bonding]
> [ 98.503039] [<ffffffffa02af46b>] bond_do_ioctl+0x37b/0x400 [bonding]
> [ 98.503039] [<ffffffff81101d8d>] ? trace_hardirqs_on+0xd/0x10
> [ 98.503039] [<ffffffff816dc437>] ? rtnl_lock+0x17/0x20
> [ 98.503039] [<ffffffff816e5fd1>] dev_ifsioc+0x331/0x3e0
> [ 98.503039] [<ffffffff816e62dc>] dev_ioctl+0xec/0x6c0
> [ 98.503039] [<ffffffff816a6c6a>] sock_do_ioctl+0x4a/0x60
> [ 98.503039] [<ffffffff816a7300>] sock_ioctl+0x1c0/0x250
> [ 98.503039] [<ffffffff81271bfe>] do_vfs_ioctl+0x2ee/0x540
> [ 98.503039] [<ffffffff810fd943>] ? up_read+0x23/0x40
> [ 98.503039] [<ffffffff81070993>] ? __do_page_fault+0x1d3/0x420
> [ 98.503039] [<ffffffff8127e246>] ? __fget_light+0x66/0x90
> [ 98.503039] [<ffffffff81271ec9>] SyS_ioctl+0x79/0x90
> [ 98.503039] [<ffffffff8184936e>] entry_SYSCALL_64_fastpath+0x12/0x76
> [ 98.503039] ---[ end trace 00cfa804b0670051 ]---
>
> Fixes: 616f45416ca0 ("bonding: implement bond_poll_controller()")
> Signed-off-by: Nikolay Aleksandrov <niko...@cumulusnetworks.com>
Acked-by: Mahesh Bandewar <mahe...@google.com>
> ---
> v3: After Dave made it clear that poll_controller should always be called
> with interrupts disabled we can simply drop the rcu bh lock.
>
I agree with Dave's logic and future users probably have to follow the
same logic.
> drivers/net/bonding/bond_main.c | 2 --
> 1 file changed, 2 deletions(-)
>
> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
> index a98dd4f1b0e3..7ab72692d7fd 100644
> --- a/drivers/net/bonding/bond_main.c
> +++ b/drivers/net/bonding/bond_main.c
> @@ -979,7 +979,6 @@ static void bond_poll_controller(struct net_device
> *bond_dev)
> if (bond_3ad_get_active_agg_info(bond, &ad_info))
> return;
>
> - rcu_read_lock_bh();
> bond_for_each_slave_rcu(bond, slave, iter) {
> ops = slave->dev->netdev_ops;
> if (!bond_slave_is_up(slave) || !ops->ndo_poll_controller)
> @@ -1000,7 +999,6 @@ static void bond_poll_controller(struct net_device
> *bond_dev)
> ops->ndo_poll_controller(slave->dev);
> up(&ni->dev_lock);
> }
> - rcu_read_unlock_bh();
> }
>
> static void bond_netpoll_cleanup(struct net_device *bond_dev)
> --
> 2.4.3
>
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