From f04b514c0ce2f20aad757ebfb04e07b1a12d2b58 Mon Sep 17 00:00:00 2001 From: Vladimir Oltean Date: Fri, 30 Aug 2019 04:07:22 +0300 Subject: taprio: Set default link speed to 10 Mbps in taprio_set_picos_per_byte The taprio budget needs to be adapted at runtime according to interface link speed. But that handling is problematic. For one thing, installing a qdisc on an interface that doesn't have carrier is not illegal. But taprio prints the following stack trace: [ 31.851373] ------------[ cut here ]------------ [ 31.856024] WARNING: CPU: 1 PID: 207 at net/sched/sch_taprio.c:481 taprio_dequeue+0x1a8/0x2d4 [ 31.864566] taprio: dequeue() called with unknown picos per byte. [ 31.864570] Modules linked in: [ 31.873701] CPU: 1 PID: 207 Comm: tc Not tainted 5.3.0-rc5-01199-g8838fe023cd6 #1689 [ 31.881398] Hardware name: Freescale LS1021A [ 31.885661] [] (unwind_backtrace) from [] (show_stack+0x10/0x14) [ 31.893368] [] (show_stack) from [] (dump_stack+0xb4/0xc8) [ 31.900555] [] (dump_stack) from [] (__warn+0xe0/0xf8) [ 31.907395] [] (__warn) from [] (warn_slowpath_fmt+0x48/0x6c) [ 31.914841] [] (warn_slowpath_fmt) from [] (taprio_dequeue+0x1a8/0x2d4) [ 31.923150] [] (taprio_dequeue) from [] (__qdisc_run+0x90/0x61c) [ 31.930856] [] (__qdisc_run) from [] (net_tx_action+0x12c/0x2bc) [ 31.938560] [] (net_tx_action) from [] (__do_softirq+0x130/0x3c8) [ 31.946350] [] (__do_softirq) from [] (irq_exit+0xbc/0xd8) [ 31.953536] [] (irq_exit) from [] (__handle_domain_irq+0x60/0xb4) [ 31.961328] [] (__handle_domain_irq) from [] (gic_handle_irq+0x58/0x9c) [ 31.969638] [] (gic_handle_irq) from [] (__irq_svc+0x6c/0x90) [ 31.977076] Exception stack(0xe8167b20 to 0xe8167b68) [ 31.982100] 7b20: e9d4bd80 00000cc0 000000cf 00000000 e9d4bd80 c1f38958 00000cc0 c1f38960 [ 31.990234] 7b40: 00000001 000000cf 00000004 e9dc0800 00000000 e8167b70 c0f478ec c0f46d94 [ 31.998363] 7b60: 60070013 ffffffff [ 32.001833] [] (__irq_svc) from [] (netlink_trim+0x18/0xd8) [ 32.009104] [] (netlink_trim) from [] (netlink_broadcast_filtered+0x34/0x414) [ 32.017930] [] (netlink_broadcast_filtered) from [] (netlink_broadcast+0x20/0x28) [ 32.027102] [] (netlink_broadcast) from [] (rtnetlink_send+0x34/0x88) [ 32.035238] [] (rtnetlink_send) from [] (notify_and_destroy+0x2c/0x44) [ 32.043461] [] (notify_and_destroy) from [] (qdisc_graft+0x398/0x470) [ 32.051595] [] (qdisc_graft) from [] (tc_modify_qdisc+0x3a4/0x724) [ 32.059470] [] (tc_modify_qdisc) from [] (rtnetlink_rcv_msg+0x260/0x2ec) [ 32.067864] [] (rtnetlink_rcv_msg) from [] (netlink_rcv_skb+0xb8/0x110) [ 32.076172] [] (netlink_rcv_skb) from [] (netlink_unicast+0x1b4/0x22c) [ 32.084392] [] (netlink_unicast) from [] (netlink_sendmsg+0x33c/0x380) [ 32.092614] [] (netlink_sendmsg) from [] (sock_sendmsg+0x14/0x24) [ 32.100403] [] (sock_sendmsg) from [] (___sys_sendmsg+0x214/0x228) [ 32.108279] [] (___sys_sendmsg) from [] (__sys_sendmsg+0x50/0x8c) [ 32.116068] [] (__sys_sendmsg) from [] (ret_fast_syscall+0x0/0x54) [ 32.123938] Exception stack(0xe8167fa8 to 0xe8167ff0) [ 32.128960] 7fa0: b6fa68c8 000000f8 00000003 bea142d0 00000000 00000000 [ 32.137093] 7fc0: b6fa68c8 000000f8 0052154c 00000128 5d6468a2 00000000 00000028 00558c9c [ 32.145224] 7fe0: 00000070 bea14278 00530d64 b6e17e64 [ 32.150659] ---[ end trace 2139c9827c3e5177 ]--- This happens because the qdisc ->dequeue callback gets called. Which again is not illegal, the qdisc will dequeue even when the interface is up but doesn't have carrier (and hence SPEED_UNKNOWN), and the frames will be dropped further down the stack in dev_direct_xmit(). And, at the end of the day, for what? For calculating the initial budget of an interface which is non-operational at the moment and where frames will get dropped anyway. So if we can't figure out the link speed, default to SPEED_10 and move along. We can also remove the runtime check now. Cc: Leandro Dorileo Fixes: 7b9eba7ba0c1 ("net/sched: taprio: fix picos_per_byte miscalculation") Acked-by: Vinicius Costa Gomes Signed-off-by: Vladimir Oltean Signed-off-by: David S. Miller --- net/sched/sch_taprio.c | 23 +++++++++++++---------- 1 file changed, 13 insertions(+), 10 deletions(-) (limited to 'net') diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c index 8c85f61e98dd..8d8bc2ec5cd6 100644 --- a/net/sched/sch_taprio.c +++ b/net/sched/sch_taprio.c @@ -477,11 +477,6 @@ static struct sk_buff *taprio_dequeue(struct Qdisc *sch) u32 gate_mask; int i; - if (atomic64_read(&q->picos_per_byte) == -1) { - WARN_ONCE(1, "taprio: dequeue() called with unknown picos per byte."); - return NULL; - } - rcu_read_lock(); entry = rcu_dereference(q->current_entry); /* if there's no entry, it means that the schedule didn't @@ -958,12 +953,20 @@ static void taprio_set_picos_per_byte(struct net_device *dev, struct taprio_sched *q) { struct ethtool_link_ksettings ecmd; - int picos_per_byte = -1; + int speed = SPEED_10; + int picos_per_byte; + int err; + + err = __ethtool_get_link_ksettings(dev, &ecmd); + if (err < 0) + goto skip; + + if (ecmd.base.speed != SPEED_UNKNOWN) + speed = ecmd.base.speed; - if (!__ethtool_get_link_ksettings(dev, &ecmd) && - ecmd.base.speed != SPEED_UNKNOWN) - picos_per_byte = div64_s64(NSEC_PER_SEC * 1000LL * 8, - ecmd.base.speed * 1000 * 1000); +skip: + picos_per_byte = div64_s64(NSEC_PER_SEC * 1000LL * 8, + speed * 1000 * 1000); atomic64_set(&q->picos_per_byte, picos_per_byte); netdev_dbg(dev, "taprio: set %s's picos_per_byte to: %lld, linkspeed: %d\n", -- cgit v1.2.3-58-ga151