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w1ldptr
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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+ kernel-patches#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] kernel-patches#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+ kernel-patches#646 [ 509.361216] Hardware name: Supermicro SYS-2028TP-DECR/X10DRT-P, BIOS 2.0b 03/30/2017 Fixes: ef6980b ("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>
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‎net/sched/act_ife.c‎

Lines changed: 10 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -167,16 +167,16 @@ static struct tcf_meta_ops *find_ife_oplist(u16 metaid)
167167
{
168168
struct tcf_meta_ops *o;
169169

170-
read_lock(&ife_mod_lock);
170+
read_lock_bh(&ife_mod_lock);
171171
list_for_each_entry(o, &ifeoplist, list) {
172172
if (o->metaid == metaid) {
173173
if (!try_module_get(o->owner))
174174
o = NULL;
175-
read_unlock(&ife_mod_lock);
175+
read_unlock_bh(&ife_mod_lock);
176176
return o;
177177
}
178178
}
179-
read_unlock(&ife_mod_lock);
179+
read_unlock_bh(&ife_mod_lock);
180180

181181
return NULL;
182182
}
@@ -190,12 +190,12 @@ int register_ife_op(struct tcf_meta_ops *mops)
190190
!mops->get || !mops->alloc)
191191
return -EINVAL;
192192

193-
write_lock(&ife_mod_lock);
193+
write_lock_bh(&ife_mod_lock);
194194

195195
list_for_each_entry(m, &ifeoplist, list) {
196196
if (m->metaid == mops->metaid ||
197197
(strcmp(mops->name, m->name) == 0)) {
198-
write_unlock(&ife_mod_lock);
198+
write_unlock_bh(&ife_mod_lock);
199199
return -EEXIST;
200200
}
201201
}
@@ -204,7 +204,7 @@ int register_ife_op(struct tcf_meta_ops *mops)
204204
mops->release = ife_release_meta_gen;
205205

206206
list_add_tail(&mops->list, &ifeoplist);
207-
write_unlock(&ife_mod_lock);
207+
write_unlock_bh(&ife_mod_lock);
208208
return 0;
209209
}
210210
EXPORT_SYMBOL_GPL(unregister_ife_op);
@@ -214,15 +214,15 @@ int unregister_ife_op(struct tcf_meta_ops *mops)
214214
struct tcf_meta_ops *m;
215215
int err = -ENOENT;
216216

217-
write_lock(&ife_mod_lock);
217+
write_lock_bh(&ife_mod_lock);
218218
list_for_each_entry(m, &ifeoplist, list) {
219219
if (m->metaid == mops->metaid) {
220220
list_del(&mops->list);
221221
err = 0;
222222
break;
223223
}
224224
}
225-
write_unlock(&ife_mod_lock);
225+
write_unlock_bh(&ife_mod_lock);
226226

227227
return err;
228228
}
@@ -343,13 +343,13 @@ static int use_all_metadata(struct tcf_ife_info *ife)
343343
int rc = 0;
344344
int installed = 0;
345345

346-
read_lock(&ife_mod_lock);
346+
read_lock_bh(&ife_mod_lock);
347347
list_for_each_entry(o, &ifeoplist, list) {
348348
rc = add_metainfo(ife, o->metaid, NULL, 0, true);
349349
if (rc == 0)
350350
installed += 1;
351351
}
352-
read_unlock(&ife_mod_lock);
352+
read_unlock_bh(&ife_mod_lock);
353353

354354
if (installed)
355355
return 0;

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