net: sched: act_ife: disable bh when taking ife_mod_lock

Lockdep reports deadlock for following locking scenario in ife action:

Task one:
1) Executes ife action update.
2) Takes tcfa_lock.
3) Waits on ife_mod_lock which is already taken by task two.

Task two:

1) Executes any path that obtains ife_mod_lock without disabling bh (any
path that takes ife_mod_lock while holding tcfa_lock has bh disabled) like
loading a meta module, or creating new action.
2) Takes ife_mod_lock.
3) Task is preempted by rate estimator timer.
4) Timer callback waits on tcfa_lock which is taken by task one.

In described case tasks deadlock because they take same two locks in
different order. To prevent potential deadlock reported by lockdep, always
disable bh when obtaining ife_mod_lock.

Lockdep warning:

[  508.101192] =====================================================
[  508.107708] WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected
[  508.114728] 4.18.0-rc8+ #646 Not tainted
[  508.119050] -----------------------------------------------------
[  508.125559] tc/5460 [HC0[0]:SC0[2]:HE1:SE0] is trying to acquire:
[  508.132025] 000000005a938c68 (ife_mod_lock){++++}, at: find_ife_oplist+0x1e/0xc0 [act_ife]
[  508.140996]
               and this task is already holding:
[  508.147548] 00000000d46f6c56 (&(&p->tcfa_lock)->rlock){+.-.}, at: tcf_ife_init+0x6ae/0xf40 [act_ife]
[  508.157371] which would create a new lock dependency:
[  508.162828]  (&(&p->tcfa_lock)->rlock){+.-.} -> (ife_mod_lock){++++}
[  508.169572]
               but this new dependency connects a SOFTIRQ-irq-safe lock:
[  508.178197]  (&(&p->tcfa_lock)->rlock){+.-.}
[  508.178201]
               ... which became SOFTIRQ-irq-safe at:
[  508.189771]   _raw_spin_lock+0x2c/0x40
[  508.193906]   est_fetch_counters+0x41/0xb0
[  508.198391]   est_timer+0x83/0x3c0
[  508.202180]   call_timer_fn+0x16a/0x5d0
[  508.206400]   run_timer_softirq+0x399/0x920
[  508.210967]   __do_softirq+0x157/0x97d
[  508.215102]   irq_exit+0x152/0x1c0
[  508.218888]   smp_apic_timer_interrupt+0xc0/0x4e0
[  508.223976]   apic_timer_interrupt+0xf/0x20
[  508.228540]   cpuidle_enter_state+0xf8/0x5d0
[  508.233198]   do_idle+0x28a/0x350
[  508.236881]   cpu_startup_entry+0xc7/0xe0
[  508.241296]   start_secondary+0x2e8/0x3f0
[  508.245678]   secondary_startup_64+0xa5/0xb0
[  508.250347]
               to a SOFTIRQ-irq-unsafe lock:  (ife_mod_lock){++++}
[  508.256531]
               ... which became SOFTIRQ-irq-unsafe at:
[  508.267279] ...
[  508.267283]   _raw_write_lock+0x2c/0x40
[  508.273653]   register_ife_op+0x118/0x2c0 [act_ife]
[  508.278926]   do_one_initcall+0xf7/0x4d9
[  508.283214]   do_init_module+0x18b/0x44e
[  508.287521]   load_module+0x4167/0x5730
[  508.291739]   __do_sys_finit_module+0x16d/0x1a0
[  508.296654]   do_syscall_64+0x7a/0x3f0
[  508.300788]   entry_SYSCALL_64_after_hwframe+0x49/0xbe
[  508.306302]
               other info that might help us debug this:

[  508.315286]  Possible interrupt unsafe locking scenario:

[  508.322771]        CPU0                    CPU1
[  508.327681]        ----                    ----
[  508.332604]   lock(ife_mod_lock);
[  508.336300]                                local_irq_disable();
[  508.342608]                                lock(&(&p->tcfa_lock)->rlock);
[  508.349793]                                lock(ife_mod_lock);
[  508.355990]   <Interrupt>
[  508.358974]     lock(&(&p->tcfa_lock)->rlock);
[  508.363803]
                *** DEADLOCK ***

[  508.370715] 2 locks held by tc/5460:
[  508.374680]  #0: 00000000e27e4fa4 (rtnl_mutex){+.+.}, at: rtnetlink_rcv_msg+0x583/0x7b0
[  508.383366]  #1: 00000000d46f6c56 (&(&p->tcfa_lock)->rlock){+.-.}, at: tcf_ife_init+0x6ae/0xf40 [act_ife]
[  508.393648]
               the dependencies between SOFTIRQ-irq-safe lock and the holding lock:
[  508.403505] -> (&(&p->tcfa_lock)->rlock){+.-.} ops: 1001553 {
[  508.409646]    HARDIRQ-ON-W at:
[  508.413136]                     _raw_spin_lock_bh+0x34/0x40
[  508.419059]                     gnet_stats_start_copy_compat+0xa2/0x230
[  508.426021]                     gnet_stats_start_copy+0x16/0x20
[  508.432333]                     tcf_action_copy_stats+0x95/0x1d0
[  508.438735]                     tcf_action_dump_1+0xb0/0x4e0
[  508.444795]                     tcf_action_dump+0xca/0x200
[  508.450673]                     tcf_exts_dump+0xd9/0x320
[  508.456392]                     fl_dump+0x1b7/0x4a0 [cls_flower]
[  508.462798]                     tcf_fill_node+0x380/0x530
[  508.468601]                     tfilter_notify+0xdf/0x1c0
[  508.474404]                     tc_new_tfilter+0x84a/0xc90
[  508.480270]                     rtnetlink_rcv_msg+0x5bd/0x7b0
[  508.486419]                     netlink_rcv_skb+0x184/0x220
[  508.492394]                     netlink_unicast+0x31b/0x460
[  508.507411]                     netlink_sendmsg+0x3fb/0x840
[  508.513390]                     sock_sendmsg+0x7b/0xd0
[  508.518907]                     ___sys_sendmsg+0x4c6/0x610
[  508.524797]                     __sys_sendmsg+0xd7/0x150
[  508.530510]                     do_syscall_64+0x7a/0x3f0
[  508.536201]                     entry_SYSCALL_64_after_hwframe+0x49/0xbe
[  508.543301]    IN-SOFTIRQ-W at:
[  508.546834]                     _raw_spin_lock+0x2c/0x40
[  508.552522]                     est_fetch_counters+0x41/0xb0
[  508.558571]                     est_timer+0x83/0x3c0
[  508.563912]                     call_timer_fn+0x16a/0x5d0
[  508.569699]                     run_timer_softirq+0x399/0x920
[  508.575840]                     __do_softirq+0x157/0x97d
[  508.581538]                     irq_exit+0x152/0x1c0
[  508.586882]                     smp_apic_timer_interrupt+0xc0/0x4e0
[  508.593533]                     apic_timer_interrupt+0xf/0x20
[  508.599686]                     cpuidle_enter_state+0xf8/0x5d0
[  508.605895]                     do_idle+0x28a/0x350
[  508.611147]                     cpu_startup_entry+0xc7/0xe0
[  508.617097]                     start_secondary+0x2e8/0x3f0
[  508.623029]                     secondary_startup_64+0xa5/0xb0
[  508.629245]    INITIAL USE at:
[  508.632686]                    _raw_spin_lock_bh+0x34/0x40
[  508.638557]                    gnet_stats_start_copy_compat+0xa2/0x230
[  508.645491]                    gnet_stats_start_copy+0x16/0x20
[  508.651719]                    tcf_action_copy_stats+0x95/0x1d0
[  508.657992]                    tcf_action_dump_1+0xb0/0x4e0
[  508.663937]                    tcf_action_dump+0xca/0x200
[  508.669716]                    tcf_exts_dump+0xd9/0x320
[  508.675337]                    fl_dump+0x1b7/0x4a0 [cls_flower]
[  508.681650]                    tcf_fill_node+0x380/0x530
[  508.687366]                    tfilter_notify+0xdf/0x1c0
[  508.693031]                    tc_new_tfilter+0x84a/0xc90
[  508.698820]                    rtnetlink_rcv_msg+0x5bd/0x7b0
[  508.704869]                    netlink_rcv_skb+0x184/0x220
[  508.710758]                    netlink_unicast+0x31b/0x460
[  508.716627]                    netlink_sendmsg+0x3fb/0x840
[  508.722510]                    sock_sendmsg+0x7b/0xd0
[  508.727931]                    ___sys_sendmsg+0x4c6/0x610
[  508.733729]                    __sys_sendmsg+0xd7/0x150
[  508.739346]                    do_syscall_64	+0x7a/0x3f0
[  508.744943]                    entry_SYSCALL_64_after_hwframe+0x49/0xbe
[  508.751930]  }
[  508.753964]  ... key      at: [<ffffffff916b3e20>] __key.61145+0x0/0x40
[  508.760946]  ... acquired at:
[  508.764294]    _raw_read_lock+0x2f/0x40
[  508.768513]    find_ife_oplist+0x1e/0xc0 [act_ife]
[  508.773692]    tcf_ife_init+0x82f/0xf40 [act_ife]
[  508.778785]    tcf_action_init_1+0x510/0x750
[  508.783468]    tcf_action_init+0x1e8/0x340
[  508.787938]    tcf_action_add+0xc5/0x240
[  508.792241]    tc_ctl_action+0x203/0x2a0
[  508.796550]    rtnetlink_rcv_msg+0x5bd/0x7b0
[  508.801200]    netlink_rcv_skb+0x184/0x220
[  508.805674]    netlink_unicast+0x31b/0x460
[  508.810129]    netlink_sendmsg+0x3fb/0x840
[  508.814611]    sock_sendmsg+0x7b/0xd0
[  508.818665]    ___sys_sendmsg+0x4c6/0x610
[  508.823029]    __sys_sendmsg+0xd7/0x150
[  508.827246]    do_syscall_64+0x7a/0x3f0
[  508.831483]    entry_SYSCALL_64_after_hwframe+0x49/0xbe

               the dependencies between the lock to be acquired
[  508.838945]  and SOFTIRQ-irq-unsafe lock:
[  508.851177] -> (ife_mod_lock){++++} ops: 95 {
[  508.855920]    HARDIRQ-ON-W at:
[  508.859478]                     _raw_write_lock+0x2c/0x40
[  508.865264]                     register_ife_op+0x118/0x2c0 [act_ife]
[  508.872071]                     do_one_initcall+0xf7/0x4d9
[  508.877947]                     do_init_module+0x18b/0x44e
[  508.883819]                     load_module+0x4167/0x5730
[  508.889595]                     __do_sys_finit_module+0x16d/0x1a0
[  508.896043]                     do_syscall_64+0x7a/0x3f0
[  508.901734]                     entry_SYSCALL_64_after_hwframe+0x49/0xbe
[  508.908827]    HARDIRQ-ON-R at:
[  508.912359]                     _raw_read_lock+0x2f/0x40
[  508.918043]                     find_ife_oplist+0x1e/0xc0 [act_ife]
[  508.924692]                     tcf_ife_init+0x82f/0xf40 [act_ife]
[  508.931252]                     tcf_action_init_1+0x510/0x750
[  508.937393]                     tcf_action_init+0x1e8/0x340
[  508.943366]                     tcf_action_add+0xc5/0x240
[  508.949130]                     tc_ctl_action+0x203/0x2a0
[  508.954922]                     rtnetlink_rcv_msg+0x5bd/0x7b0
[  508.961024]                     netlink_rcv_skb+0x184/0x220
[  508.966970]                     netlink_unicast+0x31b/0x460
[  508.972915]                     netlink_sendmsg+0x3fb/0x840
[  508.978859]                     sock_sendmsg+0x7b/0xd0
[  508.984400]                     ___sys_sendmsg+0x4c6/0x610
[  508.990264]                     __sys_sendmsg+0xd7/0x150
[  508.995952]                     do_syscall_64+0x7a/0x3f0
[  509.001643]                     entry_SYSCALL_64_after_hwframe+0x49/0xbe
[  509.008722]    SOFTIRQ-ON-W at:\
[  509.012242]                     _raw_write_lock+0x2c/0x40
[  509.018013]                     register_ife_op+0x118/0x2c0 [act_ife]
[  509.024841]                     do_one_initcall+0xf7/0x4d9
[  509.030720]                     do_init_module+0x18b/0x44e
[  509.036604]                     load_module+0x4167/0x5730
[  509.042397]                     __do_sys_finit_module+0x16d/0x1a0
[  509.048865]                     do_syscall_64+0x7a/0x3f0
[  509.054551]                     entry_SYSCALL_64_after_hwframe+0x49/0xbe
[  509.061636]    SOFTIRQ-ON-R at:
[  509.065145]                     _raw_read_lock+0x2f/0x40
[  509.070854]                     find_ife_oplist+0x1e/0xc0 [act_ife]
[  509.077515]                     tcf_ife_init+0x82f/0xf40 [act_ife]
[  509.084051]                     tcf_action_init_1+0x510/0x750
[  509.090172]                     tcf_action_init+0x1e8/0x340
[  509.096124]                     tcf_action_add+0xc5/0x240
[  509.101891]                     tc_ctl_action+0x203/0x2a0
[  509.107671]                     rtnetlink_rcv_msg+0x5bd/0x7b0
[  509.113811]                     netlink_rcv_skb+0x184/0x220
[  509.119768]                     netlink_unicast+0x31b/0x460
[  509.125716]                     netlink_sendmsg+0x3fb/0x840
[  509.131668]                     sock_sendmsg+0x7b/0xd0
[  509.137167]                     ___sys_sendmsg+0x4c6/0x610
[  509.143010]                     __sys_sendmsg+0xd7/0x150
[  509.148718]                     do_syscall_64+0x7a/0x3f0
[  509.154443]                     entry_SYSCALL_64_after_hwframe+0x49/0xbe
[  509.161533]    INITIAL USE at:
[  509.164956]                    _raw_read_lock+0x2f/0x40
[  509.170574]                    find_ife_oplist+0x1e/0xc0 [act_ife]
[  509.177134]                    tcf_ife_init+0x82f/0xf40 [act_ife]
[  509.183619]                    tcf_action_init_1+0x510/0x750
[  509.189674]                    tcf_action_init+0x1e8/0x340
[  509.195534]                    tcf_action_add+0xc5/0x240
[  509.201229]                    tc_ctl_action+0x203/0x2a0
[  509.206920]                    rtnetlink_rcv_msg+0x5bd/0x7b0
[  509.212936]                    netlink_rcv_skb+0x184/0x220
[  509.218818]                    netlink_unicast+0x31b/0x460
[  509.224699]                    netlink_sendmsg+0x3fb/0x840
[  509.230581]                    sock_sendmsg+0x7b/0xd0
[  509.235984]                    ___sys_sendmsg+0x4c6/0x610
[  509.241791]                    __sys_sendmsg+0xd7/0x150
[  509.247425]                    do_syscall_64+0x7a/0x3f0
[  509.253007]                    entry_SYSCALL_64_after_hwframe+0x49/0xbe
[  509.259975]  }
[  509.261998]  ... key      at: [<ffffffffc1554258>] ife_mod_lock+0x18/0xffffffffffff8dc0 [act_ife]
[  509.271569]  ... acquired at:
[  509.274912]    _raw_read_lock+0x2f/0x40
[  509.279134]    find_ife_oplist+0x1e/0xc0 [act_ife]
[  509.284324]    tcf_ife_init+0x82f/0xf40 [act_ife]
[  509.289425]    tcf_action_init_1+0x510/0x750
[  509.294068]    tcf_action_init+0x1e8/0x340
[  509.298553]    tcf_action_add+0xc5/0x240
[  509.302854]    tc_ctl_action+0x203/0x2a0
[  509.307153]    rtnetlink_rcv_msg+0x5bd/0x7b0
[  509.311805]    netlink_rcv_skb+0x184/0x220
[  509.316282]    netlink_unicast+0x31b/0x460
[  509.320769]    netlink_sendmsg+0x3fb/0x840
[  509.325248]    sock_sendmsg+0x7b/0xd0
[  509.329290]    ___sys_sendmsg+0x4c6/0x610
[  509.333687]    __sys_sendmsg+0xd7/0x150
[  509.337902]    do_syscall_64+0x7a/0x3f0
[  509.342116]    entry_SYSCALL_64_after_hwframe+0x49/0xbe
[  509.349601]
               stack backtrace:
[  509.354663] CPU: 6 PID: 5460 Comm: tc Not tainted 4.18.0-rc8+ #646
[  509.361216] Hardware name: Supermicro SYS-2028TP-DECR/X10DRT-P, BIOS 2.0b 03/30/2017

Fixes: ef6980b6 ("introduce IFE action")
Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/act_ife.c

@@ -167,16 +167,16 @@ static struct tcf_meta_ops *find_ife_oplist(u16 metaid)
 {
 	struct tcf_meta_ops *o;
 
-	read_lock(&ife_mod_lock);
+	read_lock_bh(&ife_mod_lock);
 	list_for_each_entry(o, &ifeoplist, list) {
 		if (o->metaid == metaid) {
 			if (!try_module_get(o->owner))
 				o = NULL;
-			read_unlock(&ife_mod_lock);
+			read_unlock_bh(&ife_mod_lock);
 			return o;
 		}
 	}
-	read_unlock(&ife_mod_lock);
+	read_unlock_bh(&ife_mod_lock);
 
 	return NULL;
 }
@@ -190,12 +190,12 @@ int register_ife_op(struct tcf_meta_ops *mops)
 	    !mops->get || !mops->alloc)
 		return -EINVAL;
 
-	write_lock(&ife_mod_lock);
+	write_lock_bh(&ife_mod_lock);
 
 	list_for_each_entry(m, &ifeoplist, list) {
 		if (m->metaid == mops->metaid ||
 		    (strcmp(mops->name, m->name) == 0)) {
-			write_unlock(&ife_mod_lock);
+			write_unlock_bh(&ife_mod_lock);
 			return -EEXIST;
 		}
 	}
@@ -204,7 +204,7 @@ int register_ife_op(struct tcf_meta_ops *mops)
 		mops->release = ife_release_meta_gen;
 
 	list_add_tail(&mops->list, &ifeoplist);
-	write_unlock(&ife_mod_lock);
+	write_unlock_bh(&ife_mod_lock);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(unregister_ife_op);
@@ -214,7 +214,7 @@ int unregister_ife_op(struct tcf_meta_ops *mops)
 	struct tcf_meta_ops *m;
 	int err = -ENOENT;
 
-	write_lock(&ife_mod_lock);
+	write_lock_bh(&ife_mod_lock);
 	list_for_each_entry(m, &ifeoplist, list) {
 		if (m->metaid == mops->metaid) {
 			list_del(&mops->list);
@@ -222,7 +222,7 @@ int unregister_ife_op(struct tcf_meta_ops *mops)
 			break;
 		}
 	}
-	write_unlock(&ife_mod_lock);
+	write_unlock_bh(&ife_mod_lock);
 
 	return err;
 }
@@ -343,13 +343,13 @@ static int use_all_metadata(struct tcf_ife_info *ife)
 	int rc = 0;
 	int installed = 0;
 
-	read_lock(&ife_mod_lock);
+	read_lock_bh(&ife_mod_lock);
 	list_for_each_entry(o, &ifeoplist, list) {
 		rc = add_metainfo(ife, o->metaid, NULL, 0, true);
 		if (rc == 0)
 			installed += 1;
 	}
-	read_unlock(&ife_mod_lock);
+	read_unlock_bh(&ife_mod_lock);
 
 	if (installed)
 		return 0;