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Date: Fri, 9 Aug 2013 14:39:59 +0800
From: Ying Xue <ying.xue@...driver.com>
To: Ding Tianhong <dingtianhong@...wei.com>
CC: Jon Maloy <jon.maloy@...csson.com>,
Allan Stephens <allan.stephens@...driver.com>,
"David S. Miller" <davem@...emloft.net>,
Netdev <netdev@...r.kernel.org>,
<tipc-discussion@...ts.sourceforge.net>, <wangweidong1@...wei.com>
Subject: Re: [PATCH RESEND] tipc: avoid possible deadlock while enable and
disable bearer
On 08/09/2013 02:31 PM, Ding Tianhong wrote:
> We met lockdep warning when enable and disable the bearer for commands such as:
>
> tipc-config -netid=1234 -addr=1.1.3 -be=eth:eth0
> tipc-config -netid=1234 -addr=1.1.3 -bd=eth:eth0
>
> ---------------------------------------------------
>
> [ 327.693595] ======================================================
> [ 327.693994] [ INFO: possible circular locking dependency detected ]
> [ 327.694519] 3.11.0-rc3-wwd-default #4 Tainted: G O
> [ 327.694882] -------------------------------------------------------
> [ 327.695385] tipc-config/5825 is trying to acquire lock:
> [ 327.695754] (((timer))#2){+.-...}, at: [<ffffffff8105be80>] del_timer_sync+0x0/0xd0
> [ 327.696018]
> [ 327.696018] but task is already holding lock:
> [ 327.696018] (&(&b_ptr->lock)->rlock){+.-...}, at: [<ffffffffa02be58d>] bearer_disable+ 0xdd/0x120 [tipc]
> [ 327.696018]
> [ 327.696018] which lock already depends on the new lock.
> [ 327.696018]
> [ 327.696018]
> [ 327.696018] the existing dependency chain (in reverse order) is:
> [ 327.696018]
> [ 327.696018] -> #1 (&(&b_ptr->lock)->rlock){+.-...}:
> [ 327.696018] [<ffffffff810b3b4d>] validate_chain+0x6dd/0x870
> [ 327.696018] [<ffffffff810b40bb>] __lock_acquire+0x3db/0x670
> [ 327.696018] [<ffffffff810b4453>] lock_acquire+0x103/0x130
> [ 327.696018] [<ffffffff814d65b1>] _raw_spin_lock_bh+0x41/0x80
> [ 327.696018] [<ffffffffa02c5d48>] disc_timeout+0x18/0xd0 [tipc]
> [ 327.696018] [<ffffffff8105b92a>] call_timer_fn+0xda/0x1e0
> [ 327.696018] [<ffffffff8105bcd7>] run_timer_softirq+0x2a7/0x2d0
> [ 327.696018] [<ffffffff8105379a>] __do_softirq+0x16a/0x2e0
> [ 327.696018] [<ffffffff81053a35>] irq_exit+0xd5/0xe0
> [ 327.696018] [<ffffffff81033005>] smp_apic_timer_interrupt+0x45/0x60
> [ 327.696018] [<ffffffff814df4af>] apic_timer_interrupt+0x6f/0x80
> [ 327.696018] [<ffffffff8100b70e>] arch_cpu_idle+0x1e/0x30
> [ 327.696018] [<ffffffff810a039d>] cpu_idle_loop+0x1fd/0x280
> [ 327.696018] [<ffffffff810a043e>] cpu_startup_entry+0x1e/0x20
> [ 327.696018] [<ffffffff81031589>] start_secondary+0x89/0x90
> [ 327.696018]
> [ 327.696018] -> #0 (((timer))#2){+.-...}:
> [ 327.696018] [<ffffffff810b33fe>] check_prev_add+0x43e/0x4b0
> [ 327.696018] [<ffffffff810b3b4d>] validate_chain+0x6dd/0x870
> [ 327.696018] [<ffffffff810b40bb>] __lock_acquire+0x3db/0x670
> [ 327.696018] [<ffffffff810b4453>] lock_acquire+0x103/0x130
> [ 327.696018] [<ffffffff8105bebd>] del_timer_sync+0x3d/0xd0
> [ 327.696018] [<ffffffffa02c5855>] tipc_disc_delete+0x15/0x30 [tipc]
> [ 327.696018] [<ffffffffa02be59f>] bearer_disable+0xef/0x120 [tipc]
> [ 327.696018] [<ffffffffa02be74f>] tipc_disable_bearer+0x2f/0x60 [tipc]
> [ 327.696018] [<ffffffffa02bfb32>] tipc_cfg_do_cmd+0x2e2/0x550 [tipc]
> [ 327.696018] [<ffffffffa02c8c79>] handle_cmd+0x49/0xe0 [tipc]
> [ 327.696018] [<ffffffff8143e898>] genl_family_rcv_msg+0x268/0x340
> [ 327.696018] [<ffffffff8143ed30>] genl_rcv_msg+0x70/0xd0
> [ 327.696018] [<ffffffff8143d4c9>] netlink_rcv_skb+0x89/0xb0
> [ 327.696018] [<ffffffff8143e617>] genl_rcv+0x27/0x40
> [ 327.696018] [<ffffffff8143d21e>] netlink_unicast+0x15e/0x1b0
> [ 327.696018] [<ffffffff8143ddcf>] netlink_sendmsg+0x22f/0x400
> [ 327.696018] [<ffffffff813f7836>] __sock_sendmsg+0x66/0x80
> [ 327.696018] [<ffffffff813f7957>] sock_aio_write+0x107/0x120
> [ 327.696018] [<ffffffff8117f76d>] do_sync_write+0x7d/0xc0
> [ 327.696018] [<ffffffff8117fc56>] vfs_write+0x186/0x190
> [ 327.696018] [<ffffffff811803e0>] SyS_write+0x60/0xb0
> [ 327.696018] [<ffffffff814de852>] system_call_fastpath+0x16/0x1b
> [ 327.696018]
> [ 327.696018] other info that might help us debug this:
> [ 327.696018]
> [ 327.696018] Possible unsafe locking scenario:
> [ 327.696018]
> [ 327.696018] CPU0 CPU1
> [ 327.696018] ---- ----
> [ 327.696018] lock(&(&b_ptr->lock)->rlock);
> [ 327.696018] lock(((timer))#2);
> [ 327.696018] lock(&(&b_ptr->lock)->rlock);
> [ 327.696018] lock(((timer))#2);
> [ 327.696018]
> [ 327.696018] *** DEADLOCK ***
> [ 327.696018]
> [ 327.696018] 5 locks held by tipc-config/5825:
> [ 327.696018] #0: (cb_lock){++++++}, at: [<ffffffff8143e608>] genl_rcv+0x18/0x40
> [ 327.696018] #1: (genl_mutex){+.+.+.}, at: [<ffffffff8143ed66>] genl_rcv_msg+0xa6/0xd0
> [ 327.696018] #2: (config_mutex){+.+.+.}, at: [<ffffffffa02bf889>] tipc_cfg_do_cmd+0x39/ 0x550 [tipc]
> [ 327.696018] #3: (tipc_net_lock){++.-..}, at: [<ffffffffa02be738>] tipc_disable_bearer+ 0x18/0x60 [tipc]
> [ 327.696018] #4: (&(&b_ptr->lock)->rlock){+.-...}, at: [<ffffffffa02be58d>] bearer_disable+0xdd/0x120 [tipc]
> [ 327.696018]
> [ 327.696018] stack backtrace:
> [ 327.696018] CPU: 2 PID: 5825 Comm: tipc-config Tainted: G O 3.11.0-rc3-wwd- default #4
> [ 327.696018] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2007
> [ 327.696018] 00000000ffffffff ffff880037fa77a8 ffffffff814d03dd 0000000000000000
> [ 327.696018] ffff880037fa7808 ffff880037fa77e8 ffffffff810b1c4f 0000000037fa77e8
> [ 327.696018] ffff880037fa7808 ffff880037e4db40 0000000000000000 ffff880037e4e318
> [ 327.696018] Call Trace:
> [ 327.696018] [<ffffffff814d03dd>] dump_stack+0x4d/0xa0
> [ 327.696018] [<ffffffff810b1c4f>] print_circular_bug+0x10f/0x120
> [ 327.696018] [<ffffffff810b33fe>] check_prev_add+0x43e/0x4b0
> [ 327.696018] [<ffffffff810b3b4d>] validate_chain+0x6dd/0x870
> [ 327.696018] [<ffffffff81087a28>] ? sched_clock_cpu+0xd8/0x110
> [ 327.696018] [<ffffffff810b40bb>] __lock_acquire+0x3db/0x670
> [ 327.696018] [<ffffffff810b4453>] lock_acquire+0x103/0x130
> [ 327.696018] [<ffffffff8105be80>] ? try_to_del_timer_sync+0x70/0x70
> [ 327.696018] [<ffffffff8105bebd>] del_timer_sync+0x3d/0xd0
> [ 327.696018] [<ffffffff8105be80>] ? try_to_del_timer_sync+0x70/0x70
> [ 327.696018] [<ffffffffa02c5855>] tipc_disc_delete+0x15/0x30 [tipc]
> [ 327.696018] [<ffffffffa02be59f>] bearer_disable+0xef/0x120 [tipc]
> [ 327.696018] [<ffffffffa02be74f>] tipc_disable_bearer+0x2f/0x60 [tipc]
> [ 327.696018] [<ffffffffa02bfb32>] tipc_cfg_do_cmd+0x2e2/0x550 [tipc]
> [ 327.696018] [<ffffffff81218783>] ? security_capable+0x13/0x20
> [ 327.696018] [<ffffffffa02c8c79>] handle_cmd+0x49/0xe0 [tipc]
> [ 327.696018] [<ffffffff8143e898>] genl_family_rcv_msg+0x268/0x340
> [ 327.696018] [<ffffffff8143ed30>] genl_rcv_msg+0x70/0xd0
> [ 327.696018] [<ffffffff8143ecc0>] ? genl_lock+0x20/0x20
> [ 327.696018] [<ffffffff8143d4c9>] netlink_rcv_skb+0x89/0xb0
> [ 327.696018] [<ffffffff8143e608>] ? genl_rcv+0x18/0x40
> [ 327.696018] [<ffffffff8143e617>] genl_rcv+0x27/0x40
> [ 327.696018] [<ffffffff8143d21e>] netlink_unicast+0x15e/0x1b0
> [ 327.696018] [<ffffffff81289d7c>] ? memcpy_fromiovec+0x6c/0x90
> [ 327.696018] [<ffffffff8143ddcf>] netlink_sendmsg+0x22f/0x400
> [ 327.696018] [<ffffffff813f7836>] __sock_sendmsg+0x66/0x80
> [ 327.696018] [<ffffffff813f7957>] sock_aio_write+0x107/0x120
> [ 327.696018] [<ffffffff813fe29c>] ? release_sock+0x8c/0xa0
> [ 327.696018] [<ffffffff8117f76d>] do_sync_write+0x7d/0xc0
> [ 327.696018] [<ffffffff8117fa24>] ? rw_verify_area+0x54/0x100
> [ 327.696018] [<ffffffff8117fc56>] vfs_write+0x186/0x190
> [ 327.696018] [<ffffffff811803e0>] SyS_write+0x60/0xb0
> [ 327.696018] [<ffffffff814de852>] system_call_fastpath+0x16/0x1b
>
> -----------------------------------------------------------------------
>
> The problem is that the tipc_link_delete() will cancel the timer disc_timeout() when
> the b_ptr->lock is hold, but the disc_timeout() still call b_ptr->lock to finish the
> work, so the dead lock occurs.
>
> We should unlock the b_ptr->lock when del the disc_timeout().
>
> Remove link_timeout() still met the same problem, the patch:
>
> http://article.gmane.org/gmane.network.tipc.general/4380
>
> fix the problem, so no need to send patch for fix link_timeout() deadlock warming.
>
> Signed-off-by: Wang Weidong <wangweidong1@...wei.com>
> Signed-off-by: Ding Tianhong <dingtianhong@...wei.com>
> ---
> net/tipc/bearer.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/net/tipc/bearer.c b/net/tipc/bearer.c
> index cb29ef7..41cad5f 100644
> --- a/net/tipc/bearer.c
> +++ b/net/tipc/bearer.c
> @@ -460,6 +460,7 @@ static void bearer_disable(struct tipc_bearer *b_ptr)
> {
> struct tipc_link *l_ptr;
> struct tipc_link *temp_l_ptr;
> + struct tipc_link_req *temp_req;
>
> pr_info("Disabling bearer <%s>\n", b_ptr->name);
> spin_lock_bh(&b_ptr->lock);
> @@ -468,9 +469,12 @@ static void bearer_disable(struct tipc_bearer *b_ptr)
> list_for_each_entry_safe(l_ptr, temp_l_ptr, &b_ptr->links, link_list) {
> tipc_link_delete(l_ptr);
> }
> - if (b_ptr->link_req)
> - tipc_disc_delete(b_ptr->link_req);
> + temp_req = b_ptr->link_req;
No, here is unsafe for us. Below line should be added:
b_ptr->link_req = NULL;
Otherwise, another oops will be involved!
Regards,
Ying
> spin_unlock_bh(&b_ptr->lock);
> +
> + if (temp_req)
> + tipc_disc_delete(temp_req);
> +
> memset(b_ptr, 0, sizeof(struct tipc_bearer));
> }
>
>
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