From 9263650102bb8e4e6806587de395aae02ef76deb Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 18 Apr 2024 07:32:36 +0000 Subject: [PATCH] net_sched: cake: implement lockless cake_dump() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Instead of relying on RTNL, cake_dump() can use READ_ONCE() annotations, paired with WRITE_ONCE() ones in cake_change(). v2: addressed Simon feedback in V1: https://lore.kernel.org/netdev/20240417083549.GA3846178@kernel.org/ Signed-off-by: Eric Dumazet Cc: Toke Høiland-Jørgensen Reviewed-by: Simon Horman Acked-by: Toke Høiland-Jørgensen Signed-off-by: David S. Miller --- net/sched/sch_cake.c | 110 +++++++++++++++++++++++++------------------ 1 file changed, 63 insertions(+), 47 deletions(-) diff --git a/net/sched/sch_cake.c b/net/sched/sch_cake.c index 2eabc4dc5b79..9602dafe32e6 100644 --- a/net/sched/sch_cake.c +++ b/net/sched/sch_cake.c @@ -2572,6 +2572,8 @@ static int cake_change(struct Qdisc *sch, struct nlattr *opt, { struct cake_sched_data *q = qdisc_priv(sch); struct nlattr *tb[TCA_CAKE_MAX + 1]; + u16 rate_flags; + u8 flow_mode; int err; err = nla_parse_nested_deprecated(tb, TCA_CAKE_MAX, opt, cake_policy, @@ -2579,10 +2581,11 @@ static int cake_change(struct Qdisc *sch, struct nlattr *opt, if (err < 0) return err; + flow_mode = q->flow_mode; if (tb[TCA_CAKE_NAT]) { #if IS_ENABLED(CONFIG_NF_CONNTRACK) - q->flow_mode &= ~CAKE_FLOW_NAT_FLAG; - q->flow_mode |= CAKE_FLOW_NAT_FLAG * + flow_mode &= ~CAKE_FLOW_NAT_FLAG; + flow_mode |= CAKE_FLOW_NAT_FLAG * !!nla_get_u32(tb[TCA_CAKE_NAT]); #else NL_SET_ERR_MSG_ATTR(extack, tb[TCA_CAKE_NAT], @@ -2592,29 +2595,34 @@ static int cake_change(struct Qdisc *sch, struct nlattr *opt, } if (tb[TCA_CAKE_BASE_RATE64]) - q->rate_bps = nla_get_u64(tb[TCA_CAKE_BASE_RATE64]); + WRITE_ONCE(q->rate_bps, + nla_get_u64(tb[TCA_CAKE_BASE_RATE64])); if (tb[TCA_CAKE_DIFFSERV_MODE]) - q->tin_mode = nla_get_u32(tb[TCA_CAKE_DIFFSERV_MODE]); + WRITE_ONCE(q->tin_mode, + nla_get_u32(tb[TCA_CAKE_DIFFSERV_MODE])); + rate_flags = q->rate_flags; if (tb[TCA_CAKE_WASH]) { if (!!nla_get_u32(tb[TCA_CAKE_WASH])) - q->rate_flags |= CAKE_FLAG_WASH; + rate_flags |= CAKE_FLAG_WASH; else - q->rate_flags &= ~CAKE_FLAG_WASH; + rate_flags &= ~CAKE_FLAG_WASH; } if (tb[TCA_CAKE_FLOW_MODE]) - q->flow_mode = ((q->flow_mode & CAKE_FLOW_NAT_FLAG) | + flow_mode = ((flow_mode & CAKE_FLOW_NAT_FLAG) | (nla_get_u32(tb[TCA_CAKE_FLOW_MODE]) & CAKE_FLOW_MASK)); if (tb[TCA_CAKE_ATM]) - q->atm_mode = nla_get_u32(tb[TCA_CAKE_ATM]); + WRITE_ONCE(q->atm_mode, + nla_get_u32(tb[TCA_CAKE_ATM])); if (tb[TCA_CAKE_OVERHEAD]) { - q->rate_overhead = nla_get_s32(tb[TCA_CAKE_OVERHEAD]); - q->rate_flags |= CAKE_FLAG_OVERHEAD; + WRITE_ONCE(q->rate_overhead, + nla_get_s32(tb[TCA_CAKE_OVERHEAD])); + rate_flags |= CAKE_FLAG_OVERHEAD; q->max_netlen = 0; q->max_adjlen = 0; @@ -2623,7 +2631,7 @@ static int cake_change(struct Qdisc *sch, struct nlattr *opt, } if (tb[TCA_CAKE_RAW]) { - q->rate_flags &= ~CAKE_FLAG_OVERHEAD; + rate_flags &= ~CAKE_FLAG_OVERHEAD; q->max_netlen = 0; q->max_adjlen = 0; @@ -2632,54 +2640,58 @@ static int cake_change(struct Qdisc *sch, struct nlattr *opt, } if (tb[TCA_CAKE_MPU]) - q->rate_mpu = nla_get_u32(tb[TCA_CAKE_MPU]); + WRITE_ONCE(q->rate_mpu, + nla_get_u32(tb[TCA_CAKE_MPU])); if (tb[TCA_CAKE_RTT]) { - q->interval = nla_get_u32(tb[TCA_CAKE_RTT]); + u32 interval = nla_get_u32(tb[TCA_CAKE_RTT]); - if (!q->interval) - q->interval = 1; + WRITE_ONCE(q->interval, max(interval, 1U)); } if (tb[TCA_CAKE_TARGET]) { - q->target = nla_get_u32(tb[TCA_CAKE_TARGET]); + u32 target = nla_get_u32(tb[TCA_CAKE_TARGET]); - if (!q->target) - q->target = 1; + WRITE_ONCE(q->target, max(target, 1U)); } if (tb[TCA_CAKE_AUTORATE]) { if (!!nla_get_u32(tb[TCA_CAKE_AUTORATE])) - q->rate_flags |= CAKE_FLAG_AUTORATE_INGRESS; + rate_flags |= CAKE_FLAG_AUTORATE_INGRESS; else - q->rate_flags &= ~CAKE_FLAG_AUTORATE_INGRESS; + rate_flags &= ~CAKE_FLAG_AUTORATE_INGRESS; } if (tb[TCA_CAKE_INGRESS]) { if (!!nla_get_u32(tb[TCA_CAKE_INGRESS])) - q->rate_flags |= CAKE_FLAG_INGRESS; + rate_flags |= CAKE_FLAG_INGRESS; else - q->rate_flags &= ~CAKE_FLAG_INGRESS; + rate_flags &= ~CAKE_FLAG_INGRESS; } if (tb[TCA_CAKE_ACK_FILTER]) - q->ack_filter = nla_get_u32(tb[TCA_CAKE_ACK_FILTER]); + WRITE_ONCE(q->ack_filter, + nla_get_u32(tb[TCA_CAKE_ACK_FILTER])); if (tb[TCA_CAKE_MEMORY]) - q->buffer_config_limit = nla_get_u32(tb[TCA_CAKE_MEMORY]); + WRITE_ONCE(q->buffer_config_limit, + nla_get_u32(tb[TCA_CAKE_MEMORY])); if (tb[TCA_CAKE_SPLIT_GSO]) { if (!!nla_get_u32(tb[TCA_CAKE_SPLIT_GSO])) - q->rate_flags |= CAKE_FLAG_SPLIT_GSO; + rate_flags |= CAKE_FLAG_SPLIT_GSO; else - q->rate_flags &= ~CAKE_FLAG_SPLIT_GSO; + rate_flags &= ~CAKE_FLAG_SPLIT_GSO; } if (tb[TCA_CAKE_FWMARK]) { - q->fwmark_mask = nla_get_u32(tb[TCA_CAKE_FWMARK]); - q->fwmark_shft = q->fwmark_mask ? __ffs(q->fwmark_mask) : 0; + WRITE_ONCE(q->fwmark_mask, nla_get_u32(tb[TCA_CAKE_FWMARK])); + WRITE_ONCE(q->fwmark_shft, + q->fwmark_mask ? __ffs(q->fwmark_mask) : 0); } + WRITE_ONCE(q->rate_flags, rate_flags); + WRITE_ONCE(q->flow_mode, flow_mode); if (q->tins) { sch_tree_lock(sch); cake_reconfigure(sch); @@ -2774,68 +2786,72 @@ static int cake_dump(struct Qdisc *sch, struct sk_buff *skb) { struct cake_sched_data *q = qdisc_priv(sch); struct nlattr *opts; + u16 rate_flags; + u8 flow_mode; opts = nla_nest_start_noflag(skb, TCA_OPTIONS); if (!opts) goto nla_put_failure; - if (nla_put_u64_64bit(skb, TCA_CAKE_BASE_RATE64, q->rate_bps, - TCA_CAKE_PAD)) + if (nla_put_u64_64bit(skb, TCA_CAKE_BASE_RATE64, + READ_ONCE(q->rate_bps), TCA_CAKE_PAD)) goto nla_put_failure; - if (nla_put_u32(skb, TCA_CAKE_FLOW_MODE, - q->flow_mode & CAKE_FLOW_MASK)) + flow_mode = READ_ONCE(q->flow_mode); + if (nla_put_u32(skb, TCA_CAKE_FLOW_MODE, flow_mode & CAKE_FLOW_MASK)) goto nla_put_failure; - if (nla_put_u32(skb, TCA_CAKE_RTT, q->interval)) + if (nla_put_u32(skb, TCA_CAKE_RTT, READ_ONCE(q->interval))) goto nla_put_failure; - if (nla_put_u32(skb, TCA_CAKE_TARGET, q->target)) + if (nla_put_u32(skb, TCA_CAKE_TARGET, READ_ONCE(q->target))) goto nla_put_failure; - if (nla_put_u32(skb, TCA_CAKE_MEMORY, q->buffer_config_limit)) + if (nla_put_u32(skb, TCA_CAKE_MEMORY, + READ_ONCE(q->buffer_config_limit))) goto nla_put_failure; + rate_flags = READ_ONCE(q->rate_flags); if (nla_put_u32(skb, TCA_CAKE_AUTORATE, - !!(q->rate_flags & CAKE_FLAG_AUTORATE_INGRESS))) + !!(rate_flags & CAKE_FLAG_AUTORATE_INGRESS))) goto nla_put_failure; if (nla_put_u32(skb, TCA_CAKE_INGRESS, - !!(q->rate_flags & CAKE_FLAG_INGRESS))) + !!(rate_flags & CAKE_FLAG_INGRESS))) goto nla_put_failure; - if (nla_put_u32(skb, TCA_CAKE_ACK_FILTER, q->ack_filter)) + if (nla_put_u32(skb, TCA_CAKE_ACK_FILTER, READ_ONCE(q->ack_filter))) goto nla_put_failure; if (nla_put_u32(skb, TCA_CAKE_NAT, - !!(q->flow_mode & CAKE_FLOW_NAT_FLAG))) + !!(flow_mode & CAKE_FLOW_NAT_FLAG))) goto nla_put_failure; - if (nla_put_u32(skb, TCA_CAKE_DIFFSERV_MODE, q->tin_mode)) + if (nla_put_u32(skb, TCA_CAKE_DIFFSERV_MODE, READ_ONCE(q->tin_mode))) goto nla_put_failure; if (nla_put_u32(skb, TCA_CAKE_WASH, - !!(q->rate_flags & CAKE_FLAG_WASH))) + !!(rate_flags & CAKE_FLAG_WASH))) goto nla_put_failure; - if (nla_put_u32(skb, TCA_CAKE_OVERHEAD, q->rate_overhead)) + if (nla_put_u32(skb, TCA_CAKE_OVERHEAD, READ_ONCE(q->rate_overhead))) goto nla_put_failure; - if (!(q->rate_flags & CAKE_FLAG_OVERHEAD)) + if (!(rate_flags & CAKE_FLAG_OVERHEAD)) if (nla_put_u32(skb, TCA_CAKE_RAW, 0)) goto nla_put_failure; - if (nla_put_u32(skb, TCA_CAKE_ATM, q->atm_mode)) + if (nla_put_u32(skb, TCA_CAKE_ATM, READ_ONCE(q->atm_mode))) goto nla_put_failure; - if (nla_put_u32(skb, TCA_CAKE_MPU, q->rate_mpu)) + if (nla_put_u32(skb, TCA_CAKE_MPU, READ_ONCE(q->rate_mpu))) goto nla_put_failure; if (nla_put_u32(skb, TCA_CAKE_SPLIT_GSO, - !!(q->rate_flags & CAKE_FLAG_SPLIT_GSO))) + !!(rate_flags & CAKE_FLAG_SPLIT_GSO))) goto nla_put_failure; - if (nla_put_u32(skb, TCA_CAKE_FWMARK, q->fwmark_mask)) + if (nla_put_u32(skb, TCA_CAKE_FWMARK, READ_ONCE(q->fwmark_mask))) goto nla_put_failure; return nla_nest_end(skb, opts);