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Date: Mon, 11 Nov 2013 22:01:45 +0800 From: Ding Tianhong <dthxman@...il.com> To: Veaceslav Falico <vfalico@...hat.com> CC: Ding Tianhong <dingtianhong@...wei.com>, Jay Vosburgh <fubar@...ibm.com>, Andy Gospodarek <andy@...yhouse.net>, "David S. Miller" <davem@...emloft.net>, Nikolay Aleksandrov <nikolay@...hat.com>, Netdev <netdev@...r.kernel.org> Subject: Re: [PATCH net-next v3 0/10] bonding: rebuild the lock use for bond monitor δΊ 2013/11/11 21:06, Veaceslav Falico ει: > On Mon, Nov 11, 2013 at 08:36:04PM +0800, Ding Tianhong wrote: >> Now the bond slave list is not protected by bond lock, only by RTNL, >> but the monitor still use the bond lock to protect the slave list, >> it is useless, according to the Veaceslav's opinion, there were >> three way to fix the protect problem: >> >> 1. add bond_master_upper_dev_link() and bond_upper_dev_unlink() >> in bond->lock, but it is unsafe to call call_netdevice_notifiers() >> in write lock. >> 2. remove unused bond->lock for monitor function, only use the exist >> rtnl lock(), it will take performance loss in fast path. >> 3. use RCU to protect the slave list, of course, performance is better, >> but in slow path, it is ignored. >> >> obviously the solution 1 is not fit here, I will consider the 2 and 3 >> solution. My principle is simple, if in fast path, RCU is better, >> otherwise in slow path, both is well, but according to the Jay >> Vosburgh's >> opinion, the monitor will loss performace if use RTNL to protect the all >> slave list, so remove the bond lock and replace with RCU. >> >> The second problem is the curr_slave_lock for bond, it is too old and >> unwanted in many place, because the curr_active_slave would only be >> changed in 3 place: >> >> 1. enslave slave. >> 2. release slave. >> 3. change active slave. >> >> all above were already holding bond lock, RTNL and curr_slave_lock >> together, it is tedious and no need to add so mach lock, when change >> the curr_active_slave, you have to hold the RTNL and curr_slave_lock >> together, and when you read the curr_active_slave, RTNL or >> curr_slave_lock, >> any one of them is no problem. > > Boot-test *with the same parameters as before* gave me the following > trace[1], which is inevitable in case of mode 1 bonding. So that you've > either ignored this warning or didn't actually test mode 1, even though > your last patchset was reverted because of a regression in the same mode. > > How was this tested? > yes, you are right, it is my fault. I miss a CONFIG SET for RCU, CONFIG_PROVE_RCU, althrough I test bond several times for every mode, but I still miss it. The bond_should_notify_peers in bond_select_active_slave did not in have rcu-read critical sector. > And btw - net-next is closed. > yes, I know, but I still need widely solicited opinions, it is really a big patchset for me. I am afraid of missing something. Regards. Ding > [1]: > [ 13.847032] bonding: bond0: link status definitely up for interface > eth2. > [ 13.848732] bonding: bond0: making interface eth2 the new active one. > [ 13.850429] device eth2 entered promiscuous mode > [ 13.852168] [ 13.853833] =============================== > [ 13.855410] [ INFO: suspicious RCU usage. ] > [ 13.857017] 3.12.0-bond+ #314 Tainted: G I [ 13.858690] > ------------------------------- > [ 13.860404] drivers/net/bonding/bond_main.c:818 suspicious > rcu_dereference_check() usage! > [ 13.862006] [ 13.862006] other info that might help us debug this: > [ 13.862006] [ 13.866334] [ 13.866334] rcu_scheduler_active = 1, > debug_locks = 0 > [ 13.869296] 4 locks held by kworker/u8:3/57: > [ 13.870841] #0: (%s#4){.+.+..}, at: [<ffffffff810cfec9>] > process_one_work+0x189/0x580 > [ 13.872353] #1: ((&(&bond->arp_work)->work)){+.+...}, at: > [<ffffffff810cfec9>] process_one_work+0x189/0x580 > [ 13.873967] #2: (rtnl_mutex){+.+.+.}, at: [<ffffffff8169e765>] > rtnl_trylock+0x15/0x20 > [ 13.875569] #3: (&bond->curr_slave_lock){++.+..}, at: > [<ffffffffa00b922e>] bond_ab_arp_commit+0x12e/0x200 [bonding] > [ 13.877167] [ 13.877167] stack backtrace: > [ 13.880287] CPU: 1 PID: 57 Comm: kworker/u8:3 Tainted: G I > 3.12.0-bond+ #314 > [ 13.882011] Hardware name: Hewlett-Packard HP xw4600 > Workstation/0AA0h, BIOS 786F3 v01.15 08/28/2008 > [ 13.883585] Workqueue: bond0 bond_activebackup_arp_mon [bonding] > [ 13.885011] 0000000000000001 ffff880079e89be8 ffffffff817a9df8 > 0000000000000002 > [ 13.886564] ffff880079e80000 ffff880079e89c18 ffffffff81128d23 > ffff8800790d4b40 > [ 13.888179] ffff88007980a400 ffff8800790d4bb8 ffff8800790d4b40 > ffff880079e89c38 > [ 13.889837] Call Trace: > [ 13.891417] [<ffffffff817a9df8>] dump_stack+0x59/0x81 > [ 13.892881] [<ffffffff81128d23>] lockdep_rcu_suspicious+0x103/0x140 > [ 13.894290] [<ffffffffa00b8b61>] bond_should_notify_peers+0xb1/0x110 > [bonding] > [ 13.895686] [<ffffffffa00b8e59>] bond_change_active_slave+0x299/0x370 > [bonding] > [ 13.897118] [<ffffffffa00b9027>] bond_select_active_slave+0xf7/0x1d0 > [bonding] > [ 13.898672] [<ffffffffa00b9236>] bond_ab_arp_commit+0x136/0x200 > [bonding] > [ 13.900165] [<ffffffffa00bb98d>] > bond_activebackup_arp_mon+0x10d/0x340 [bonding] > [ 13.901709] [<ffffffffa00bb8d3>] ? > bond_activebackup_arp_mon+0x53/0x340 [bonding] > [ 13.903125] [<ffffffff810cff3a>] process_one_work+0x1fa/0x580 > [ 13.904554] [<ffffffff810cfec9>] ? process_one_work+0x189/0x580 > [ 13.906023] [<ffffffff810d231f>] worker_thread+0x11f/0x3a0 > [ 13.907506] [<ffffffff810d2200>] ? manage_workers+0x170/0x170 > [ 13.908931] [<ffffffff810dbdfe>] kthread+0xee/0x100 > [ 13.910327] [<ffffffff8112d99b>] ? __lock_release+0x13b/0x1b0 > [ 13.911677] [<ffffffff810dbd10>] ? __init_kthread_worker+0x70/0x70 > [ 13.913082] [<ffffffff817ba16c>] ret_from_fork+0x7c/0xb0 > [ 13.914478] [<ffffffff810dbd10>] ? __init_kthread_worker+0x70/0x70 > [ 13.915860] bonding: bond0: first active interface up! > [ 13.917294] bridge0: port 1(bond0) entered forwarding state > [ 13.918632] bridge0: port 1(bond0) entered forwarding state > [ 14.017018] bonding: bond0: link status definitely up for interface > eth0. > >> >> for the stability, I did not change the logic for the monitor, >> all change is clear and simple, I have test the patch set for lockdep, >> it work well and stability. >> >> v2. accept the Jay Vosburgh's opinion, remove the RTNL and replace >> with RCU, >> also add some rcu function for bond use, so the patch set reach 10. >> >> v3. accept the Nikolay Aleksandrov's opinion, remove no needed >> bond_has_slave_rcu(), >> add protection for several 3ad mode handler functions and >> current_arp_slave. >> rebuild the bond_first_slave_rcu(), make it more clear. >> >> Best Regards >> Ding Tianhong >> >> Ding Tianhong (10): >> bonding: remove the no effect lock for bond_select_active_slave() >> bonding: rebuild the lock use for bond_mii_monitor() >> bonding: rebuild the lock use for bond_alb_monitor() >> bonding: rebuild the lock use for bond_loadbalance_arp_mon() >> bonding: create bond_first_slave_rcu() >> bonding: rebuild the lock use for bond_activebackup_arp_mon() >> bonding: rebuild the lock use for bond_3ad_state_machine_handler() >> bonding: remove unwanted lock for bond_option_active_slave_set() >> bonding: remove unwanted lock for bond enslave and release >> bonding: remove unwanted lock for bond_store_primaryxxx() >> >> drivers/net/bonding/bond_3ad.c | 53 +++++++------ >> drivers/net/bonding/bond_alb.c | 34 +++------ >> drivers/net/bonding/bond_main.c | 147 >> ++++++++++++++++--------------------- >> drivers/net/bonding/bond_options.c | 2 - >> drivers/net/bonding/bond_sysfs.c | 4 - >> drivers/net/bonding/bonding.h | 9 +++ >> include/linux/netdevice.h | 16 ++++ >> net/core/dev.c | 16 ---- >> 8 files changed, 132 insertions(+), 149 deletions(-) >> >> -- >> 1.8.2.1 >> >> >> > -- > To unsubscribe from this list: send the line "unsubscribe netdev" in > the body of a message to majordomo@...r.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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