linux/net/sched/act_gact.c
Vlad Buslov 653cd284a8 net: sched: always disable bh when taking tcf_lock
Recently, ops->init() and ops->dump() of all actions were modified to
always obtain tcf_lock when accessing private action state. Actions that
don't depend on tcf_lock for synchronization with their data path use
non-bh locking API. However, tcf_lock is also used to protect rate
estimator stats in softirq context by timer callback.

Change ops->init() and ops->dump() of all actions to disable bh when using
tcf_lock to prevent deadlock reported by following lockdep warning:

[  105.470398] ================================
[  105.475014] WARNING: inconsistent lock state
[  105.479628] 4.18.0-rc8+ #664 Not tainted
[  105.483897] --------------------------------
[  105.488511] inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
[  105.494871] swapper/16/0 [HC0[0]:SC1[1]:HE1:SE0] takes:
[  105.500449] 00000000f86c012e (&(&p->tcfa_lock)->rlock){+.?.}, at: est_fetch_counters+0x3c/0xa0
[  105.509696] {SOFTIRQ-ON-W} state was registered at:
[  105.514925]   _raw_spin_lock+0x2c/0x40
[  105.519022]   tcf_bpf_init+0x579/0x820 [act_bpf]
[  105.523990]   tcf_action_init_1+0x4e4/0x660
[  105.528518]   tcf_action_init+0x1ce/0x2d0
[  105.532880]   tcf_exts_validate+0x1d8/0x200
[  105.537416]   fl_change+0x55a/0x268b [cls_flower]
[  105.542469]   tc_new_tfilter+0x748/0xa20
[  105.546738]   rtnetlink_rcv_msg+0x56a/0x6d0
[  105.551268]   netlink_rcv_skb+0x18d/0x200
[  105.555628]   netlink_unicast+0x2d0/0x370
[  105.559990]   netlink_sendmsg+0x3b9/0x6a0
[  105.564349]   sock_sendmsg+0x6b/0x80
[  105.568271]   ___sys_sendmsg+0x4a1/0x520
[  105.572547]   __sys_sendmsg+0xd7/0x150
[  105.576655]   do_syscall_64+0x72/0x2c0
[  105.580757]   entry_SYSCALL_64_after_hwframe+0x49/0xbe
[  105.586243] irq event stamp: 489296
[  105.590084] hardirqs last  enabled at (489296): [<ffffffffb507e639>] _raw_spin_unlock_irq+0x29/0x40
[  105.599765] hardirqs last disabled at (489295): [<ffffffffb507e745>] _raw_spin_lock_irq+0x15/0x50
[  105.609277] softirqs last  enabled at (489292): [<ffffffffb413a6a3>] irq_enter+0x83/0xa0
[  105.618001] softirqs last disabled at (489293): [<ffffffffb413a800>] irq_exit+0x140/0x190
[  105.626813]
               other info that might help us debug this:
[  105.633976]  Possible unsafe locking scenario:

[  105.640526]        CPU0
[  105.643325]        ----
[  105.646125]   lock(&(&p->tcfa_lock)->rlock);
[  105.650747]   <Interrupt>
[  105.653717]     lock(&(&p->tcfa_lock)->rlock);
[  105.658514]
                *** DEADLOCK ***

[  105.665349] 1 lock held by swapper/16/0:
[  105.669629]  #0: 00000000a640ad99 ((&est->timer)){+.-.}, at: call_timer_fn+0x10b/0x550
[  105.678200]
               stack backtrace:
[  105.683194] CPU: 16 PID: 0 Comm: swapper/16 Not tainted 4.18.0-rc8+ #664
[  105.690249] Hardware name: Supermicro SYS-2028TP-DECR/X10DRT-P, BIOS 2.0b 03/30/2017
[  105.698626] Call Trace:
[  105.701421]  <IRQ>
[  105.703791]  dump_stack+0x92/0xeb
[  105.707461]  print_usage_bug+0x336/0x34c
[  105.711744]  mark_lock+0x7c9/0x980
[  105.715500]  ? print_shortest_lock_dependencies+0x2e0/0x2e0
[  105.721424]  ? check_usage_forwards+0x230/0x230
[  105.726315]  __lock_acquire+0x923/0x26f0
[  105.730597]  ? debug_show_all_locks+0x240/0x240
[  105.735478]  ? mark_lock+0x493/0x980
[  105.739412]  ? check_chain_key+0x140/0x1f0
[  105.743861]  ? __lock_acquire+0x836/0x26f0
[  105.748323]  ? lock_acquire+0x12e/0x290
[  105.752516]  lock_acquire+0x12e/0x290
[  105.756539]  ? est_fetch_counters+0x3c/0xa0
[  105.761084]  _raw_spin_lock+0x2c/0x40
[  105.765099]  ? est_fetch_counters+0x3c/0xa0
[  105.769633]  est_fetch_counters+0x3c/0xa0
[  105.773995]  est_timer+0x87/0x390
[  105.777670]  ? est_fetch_counters+0xa0/0xa0
[  105.782210]  ? lock_acquire+0x12e/0x290
[  105.786410]  call_timer_fn+0x161/0x550
[  105.790512]  ? est_fetch_counters+0xa0/0xa0
[  105.795055]  ? del_timer_sync+0xd0/0xd0
[  105.799249]  ? __lock_is_held+0x93/0x110
[  105.803531]  ? mark_held_locks+0x20/0xe0
[  105.807813]  ? _raw_spin_unlock_irq+0x29/0x40
[  105.812525]  ? est_fetch_counters+0xa0/0xa0
[  105.817069]  ? est_fetch_counters+0xa0/0xa0
[  105.821610]  run_timer_softirq+0x3c4/0x9f0
[  105.826064]  ? lock_acquire+0x12e/0x290
[  105.830257]  ? __bpf_trace_timer_class+0x10/0x10
[  105.835237]  ? __lock_is_held+0x25/0x110
[  105.839517]  __do_softirq+0x11d/0x7bf
[  105.843542]  irq_exit+0x140/0x190
[  105.847208]  smp_apic_timer_interrupt+0xac/0x3b0
[  105.852182]  apic_timer_interrupt+0xf/0x20
[  105.856628]  </IRQ>
[  105.859081] RIP: 0010:cpuidle_enter_state+0xd8/0x4d0
[  105.864395] Code: 46 ff 48 89 44 24 08 0f 1f 44 00 00 31 ff e8 cf ec 46 ff 80 7c 24 07 00 0f 85 1d 02 00 00 e8 9f 90 4b ff fb 66 0f 1f 44 00 00 <4c> 8b 6c 24 08 4d 29 fd 0f 80 36 03 00 00 4c 89 e8 48 ba cf f7 53
[  105.884288] RSP: 0018:ffff8803ad94fd20 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
[  105.892494] RAX: 0000000000000000 RBX: ffffe8fb300829c0 RCX: ffffffffb41e19e1
[  105.899988] RDX: 0000000000000007 RSI: dffffc0000000000 RDI: ffff8803ad9358ac
[  105.907503] RBP: ffffffffb6636300 R08: 0000000000000004 R09: 0000000000000000
[  105.914997] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000004
[  105.922487] R13: ffffffffb6636140 R14: ffffffffb66362d8 R15: 000000188d36091b
[  105.929988]  ? trace_hardirqs_on_caller+0x141/0x2d0
[  105.935232]  do_idle+0x28e/0x320
[  105.938817]  ? arch_cpu_idle_exit+0x40/0x40
[  105.943361]  ? mark_lock+0x8c1/0x980
[  105.947295]  ? _raw_spin_unlock_irqrestore+0x32/0x60
[  105.952619]  cpu_startup_entry+0xc2/0xd0
[  105.956900]  ? cpu_in_idle+0x20/0x20
[  105.960830]  ? _raw_spin_unlock_irqrestore+0x32/0x60
[  105.966146]  ? trace_hardirqs_on_caller+0x141/0x2d0
[  105.971391]  start_secondary+0x2b5/0x360
[  105.975669]  ? set_cpu_sibling_map+0x1330/0x1330
[  105.980654]  secondary_startup_64+0xa5/0xb0

Taking tcf_lock in sample action with bh disabled causes lockdep to issue a
warning regarding possible irq lock inversion dependency between tcf_lock,
and psample_groups_lock that is taken when holding tcf_lock in sample init:

[  162.108959]  Possible interrupt unsafe locking scenario:

[  162.116386]        CPU0                    CPU1
[  162.121277]        ----                    ----
[  162.126162]   lock(psample_groups_lock);
[  162.130447]                                local_irq_disable();
[  162.136772]                                lock(&(&p->tcfa_lock)->rlock);
[  162.143957]                                lock(psample_groups_lock);
[  162.150813]   <Interrupt>
[  162.153808]     lock(&(&p->tcfa_lock)->rlock);
[  162.158608]
                *** DEADLOCK ***

In order to prevent potential lock inversion dependency between tcf_lock
and psample_groups_lock, extract call to psample_group_get() from tcf_lock
protected section in sample action init function.

Fixes: 4e232818bd ("net: sched: act_mirred: remove dependency on rtnl lock")
Fixes: 764e9a2448 ("net: sched: act_vlan: remove dependency on rtnl lock")
Fixes: 729e012609 ("net: sched: act_tunnel_key: remove dependency on rtnl lock")
Fixes: d772849566 ("net: sched: act_sample: remove dependency on rtnl lock")
Fixes: e8917f4370 ("net: sched: act_gact: remove dependency on rtnl lock")
Fixes: b6a2b971c0 ("net: sched: act_csum: remove dependency on rtnl lock")
Fixes: 2142236b45 ("net: sched: act_bpf: remove dependency on rtnl lock")
Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-08-19 10:46:21 -07:00

309 lines
7.5 KiB
C

/*
* net/sched/act_gact.c Generic actions
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* copyright Jamal Hadi Salim (2002-4)
*
*/
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/skbuff.h>
#include <linux/rtnetlink.h>
#include <linux/module.h>
#include <linux/init.h>
#include <net/netlink.h>
#include <net/pkt_sched.h>
#include <linux/tc_act/tc_gact.h>
#include <net/tc_act/tc_gact.h>
static unsigned int gact_net_id;
static struct tc_action_ops act_gact_ops;
#ifdef CONFIG_GACT_PROB
static int gact_net_rand(struct tcf_gact *gact)
{
smp_rmb(); /* coupled with smp_wmb() in tcf_gact_init() */
if (prandom_u32() % gact->tcfg_pval)
return gact->tcf_action;
return gact->tcfg_paction;
}
static int gact_determ(struct tcf_gact *gact)
{
u32 pack = atomic_inc_return(&gact->packets);
smp_rmb(); /* coupled with smp_wmb() in tcf_gact_init() */
if (pack % gact->tcfg_pval)
return gact->tcf_action;
return gact->tcfg_paction;
}
typedef int (*g_rand)(struct tcf_gact *gact);
static g_rand gact_rand[MAX_RAND] = { NULL, gact_net_rand, gact_determ };
#endif /* CONFIG_GACT_PROB */
static const struct nla_policy gact_policy[TCA_GACT_MAX + 1] = {
[TCA_GACT_PARMS] = { .len = sizeof(struct tc_gact) },
[TCA_GACT_PROB] = { .len = sizeof(struct tc_gact_p) },
};
static int tcf_gact_init(struct net *net, struct nlattr *nla,
struct nlattr *est, struct tc_action **a,
int ovr, int bind, bool rtnl_held,
struct netlink_ext_ack *extack)
{
struct tc_action_net *tn = net_generic(net, gact_net_id);
struct nlattr *tb[TCA_GACT_MAX + 1];
struct tc_gact *parm;
struct tcf_gact *gact;
int ret = 0;
int err;
#ifdef CONFIG_GACT_PROB
struct tc_gact_p *p_parm = NULL;
#endif
if (nla == NULL)
return -EINVAL;
err = nla_parse_nested(tb, TCA_GACT_MAX, nla, gact_policy, NULL);
if (err < 0)
return err;
if (tb[TCA_GACT_PARMS] == NULL)
return -EINVAL;
parm = nla_data(tb[TCA_GACT_PARMS]);
#ifndef CONFIG_GACT_PROB
if (tb[TCA_GACT_PROB] != NULL)
return -EOPNOTSUPP;
#else
if (tb[TCA_GACT_PROB]) {
p_parm = nla_data(tb[TCA_GACT_PROB]);
if (p_parm->ptype >= MAX_RAND)
return -EINVAL;
}
#endif
err = tcf_idr_check_alloc(tn, &parm->index, a, bind);
if (!err) {
ret = tcf_idr_create(tn, parm->index, est, a,
&act_gact_ops, bind, true);
if (ret) {
tcf_idr_cleanup(tn, parm->index);
return ret;
}
ret = ACT_P_CREATED;
} else if (err > 0) {
if (bind)/* dont override defaults */
return 0;
if (!ovr) {
tcf_idr_release(*a, bind);
return -EEXIST;
}
} else {
return err;
}
gact = to_gact(*a);
spin_lock_bh(&gact->tcf_lock);
gact->tcf_action = parm->action;
#ifdef CONFIG_GACT_PROB
if (p_parm) {
gact->tcfg_paction = p_parm->paction;
gact->tcfg_pval = max_t(u16, 1, p_parm->pval);
/* Make sure tcfg_pval is written before tcfg_ptype
* coupled with smp_rmb() in gact_net_rand() & gact_determ()
*/
smp_wmb();
gact->tcfg_ptype = p_parm->ptype;
}
#endif
spin_unlock_bh(&gact->tcf_lock);
if (ret == ACT_P_CREATED)
tcf_idr_insert(tn, *a);
return ret;
}
static int tcf_gact_act(struct sk_buff *skb, const struct tc_action *a,
struct tcf_result *res)
{
struct tcf_gact *gact = to_gact(a);
int action = READ_ONCE(gact->tcf_action);
#ifdef CONFIG_GACT_PROB
{
u32 ptype = READ_ONCE(gact->tcfg_ptype);
if (ptype)
action = gact_rand[ptype](gact);
}
#endif
bstats_cpu_update(this_cpu_ptr(gact->common.cpu_bstats), skb);
if (action == TC_ACT_SHOT)
qstats_drop_inc(this_cpu_ptr(gact->common.cpu_qstats));
tcf_lastuse_update(&gact->tcf_tm);
return action;
}
static void tcf_gact_stats_update(struct tc_action *a, u64 bytes, u32 packets,
u64 lastuse)
{
struct tcf_gact *gact = to_gact(a);
int action = READ_ONCE(gact->tcf_action);
struct tcf_t *tm = &gact->tcf_tm;
_bstats_cpu_update(this_cpu_ptr(gact->common.cpu_bstats), bytes,
packets);
if (action == TC_ACT_SHOT)
this_cpu_ptr(gact->common.cpu_qstats)->drops += packets;
tm->lastuse = max_t(u64, tm->lastuse, lastuse);
}
static int tcf_gact_dump(struct sk_buff *skb, struct tc_action *a,
int bind, int ref)
{
unsigned char *b = skb_tail_pointer(skb);
struct tcf_gact *gact = to_gact(a);
struct tc_gact opt = {
.index = gact->tcf_index,
.refcnt = refcount_read(&gact->tcf_refcnt) - ref,
.bindcnt = atomic_read(&gact->tcf_bindcnt) - bind,
};
struct tcf_t t;
spin_lock_bh(&gact->tcf_lock);
opt.action = gact->tcf_action;
if (nla_put(skb, TCA_GACT_PARMS, sizeof(opt), &opt))
goto nla_put_failure;
#ifdef CONFIG_GACT_PROB
if (gact->tcfg_ptype) {
struct tc_gact_p p_opt = {
.paction = gact->tcfg_paction,
.pval = gact->tcfg_pval,
.ptype = gact->tcfg_ptype,
};
if (nla_put(skb, TCA_GACT_PROB, sizeof(p_opt), &p_opt))
goto nla_put_failure;
}
#endif
tcf_tm_dump(&t, &gact->tcf_tm);
if (nla_put_64bit(skb, TCA_GACT_TM, sizeof(t), &t, TCA_GACT_PAD))
goto nla_put_failure;
spin_unlock_bh(&gact->tcf_lock);
return skb->len;
nla_put_failure:
spin_unlock_bh(&gact->tcf_lock);
nlmsg_trim(skb, b);
return -1;
}
static int tcf_gact_walker(struct net *net, struct sk_buff *skb,
struct netlink_callback *cb, int type,
const struct tc_action_ops *ops,
struct netlink_ext_ack *extack)
{
struct tc_action_net *tn = net_generic(net, gact_net_id);
return tcf_generic_walker(tn, skb, cb, type, ops, extack);
}
static int tcf_gact_search(struct net *net, struct tc_action **a, u32 index,
struct netlink_ext_ack *extack)
{
struct tc_action_net *tn = net_generic(net, gact_net_id);
return tcf_idr_search(tn, a, index);
}
static size_t tcf_gact_get_fill_size(const struct tc_action *act)
{
size_t sz = nla_total_size(sizeof(struct tc_gact)); /* TCA_GACT_PARMS */
#ifdef CONFIG_GACT_PROB
if (to_gact(act)->tcfg_ptype)
/* TCA_GACT_PROB */
sz += nla_total_size(sizeof(struct tc_gact_p));
#endif
return sz;
}
static int tcf_gact_delete(struct net *net, u32 index)
{
struct tc_action_net *tn = net_generic(net, gact_net_id);
return tcf_idr_delete_index(tn, index);
}
static struct tc_action_ops act_gact_ops = {
.kind = "gact",
.type = TCA_ACT_GACT,
.owner = THIS_MODULE,
.act = tcf_gact_act,
.stats_update = tcf_gact_stats_update,
.dump = tcf_gact_dump,
.init = tcf_gact_init,
.walk = tcf_gact_walker,
.lookup = tcf_gact_search,
.get_fill_size = tcf_gact_get_fill_size,
.delete = tcf_gact_delete,
.size = sizeof(struct tcf_gact),
};
static __net_init int gact_init_net(struct net *net)
{
struct tc_action_net *tn = net_generic(net, gact_net_id);
return tc_action_net_init(tn, &act_gact_ops);
}
static void __net_exit gact_exit_net(struct list_head *net_list)
{
tc_action_net_exit(net_list, gact_net_id);
}
static struct pernet_operations gact_net_ops = {
.init = gact_init_net,
.exit_batch = gact_exit_net,
.id = &gact_net_id,
.size = sizeof(struct tc_action_net),
};
MODULE_AUTHOR("Jamal Hadi Salim(2002-4)");
MODULE_DESCRIPTION("Generic Classifier actions");
MODULE_LICENSE("GPL");
static int __init gact_init_module(void)
{
#ifdef CONFIG_GACT_PROB
pr_info("GACT probability on\n");
#else
pr_info("GACT probability NOT on\n");
#endif
return tcf_register_action(&act_gact_ops, &gact_net_ops);
}
static void __exit gact_cleanup_module(void)
{
tcf_unregister_action(&act_gact_ops, &gact_net_ops);
}
module_init(gact_init_module);
module_exit(gact_cleanup_module);