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net/sched: sch_fq_codel: annotate data-races from fq_codel_dump_class_stats()

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fq_codel_dump_class_stats() acquires qdisc spinlock only when requested
to follow flow->head chain.

As we did in sch_cake recently, add the missing READ_ONCE()/WRITE_ONCE()
annotations.

Fixes: edb09eb17e ("net: sched: do not acquire qdisc spinlock in qdisc/class stats dump")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Jamal Hadi Salim <jhs@mojatatu.com>
Link: https://patch.msgid.link/20260504163842.1162001-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet 2026-05-04 16:38:42 +00:00 committed by Jakub Kicinski
parent 40aa9fcea0
commit f83e07b292
1 changed files with 20 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

39
net/sched/sch_fq_codel.c
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@ -117,7 +117,7 @@ static inline struct sk_buff *dequeue_head(struct fq_codel_flow *flow)
{ {
struct sk_buff *skb = flow->head; struct sk_buff *skb = flow->head;
flow->head = skb->next; WRITE_ONCE(flow->head, skb->next);
skb_mark_not_on_list(skb); skb_mark_not_on_list(skb);
return skb; return skb;
} }
@ -127,7 +127,7 @@ static inline void flow_queue_add(struct fq_codel_flow *flow,
struct sk_buff *skb) struct sk_buff *skb)
{ {
if (flow->head == NULL) if (flow->head == NULL)
flow->head = skb; WRITE_ONCE(flow->head, skb);
else else
flow->tail->next = skb; flow->tail->next = skb;
flow->tail = skb; flow->tail = skb;
@ -173,8 +173,8 @@ static unsigned int fq_codel_drop(struct Qdisc *sch, unsigned int max_packets,
} while (++i < max_packets && len < threshold); } while (++i < max_packets && len < threshold);
/* Tell codel to increase its signal strength also */ /* Tell codel to increase its signal strength also */
flow->cvars.count += i; WRITE_ONCE(flow->cvars.count, flow->cvars.count + i);
q->backlogs[idx] -= len; WRITE_ONCE(q->backlogs[idx], q->backlogs[idx] - len);
q->memory_usage -= mem; q->memory_usage -= mem;
sch->qstats.drops += i; sch->qstats.drops += i;
sch->qstats.backlog -= len; sch->qstats.backlog -= len;
@ -204,13 +204,13 @@ static int fq_codel_enqueue(struct sk_buff *skb, struct Qdisc *sch,
codel_set_enqueue_time(skb); codel_set_enqueue_time(skb);
flow = &q->flows[idx]; flow = &q->flows[idx];
flow_queue_add(flow, skb); flow_queue_add(flow, skb);
q->backlogs[idx] += qdisc_pkt_len(skb); WRITE_ONCE(q->backlogs[idx], q->backlogs[idx] + qdisc_pkt_len(skb));
qdisc_qstats_backlog_inc(sch, skb); qdisc_qstats_backlog_inc(sch, skb);
if (list_empty(&flow->flowchain)) { if (list_empty(&flow->flowchain)) {
list_add_tail(&flow->flowchain, &q->new_flows); list_add_tail(&flow->flowchain, &q->new_flows);
q->new_flow_count++; q->new_flow_count++;
flow->deficit = q->quantum; WRITE_ONCE(flow->deficit, q->quantum);
} }
get_codel_cb(skb)->mem_usage = skb->truesize; get_codel_cb(skb)->mem_usage = skb->truesize;
q->memory_usage += get_codel_cb(skb)->mem_usage; q->memory_usage += get_codel_cb(skb)->mem_usage;
@ -263,7 +263,8 @@ static struct sk_buff *dequeue_func(struct codel_vars *vars, void *ctx)
flow = container_of(vars, struct fq_codel_flow, cvars); flow = container_of(vars, struct fq_codel_flow, cvars);
if (flow->head) { if (flow->head) {
skb = dequeue_head(flow); skb = dequeue_head(flow);
q->backlogs[flow - q->flows] -= qdisc_pkt_len(skb); WRITE_ONCE(q->backlogs[flow - q->flows],
q->backlogs[flow - q->flows] - qdisc_pkt_len(skb));
q->memory_usage -= get_codel_cb(skb)->mem_usage; q->memory_usage -= get_codel_cb(skb)->mem_usage;
sch->q.qlen--; sch->q.qlen--;
sch->qstats.backlog -= qdisc_pkt_len(skb); sch->qstats.backlog -= qdisc_pkt_len(skb);
@ -296,7 +297,7 @@ static struct sk_buff *fq_codel_dequeue(struct Qdisc *sch)
flow = list_first_entry(head, struct fq_codel_flow, flowchain); flow = list_first_entry(head, struct fq_codel_flow, flowchain);
if (flow->deficit <= 0) { if (flow->deficit <= 0) {
flow->deficit += q->quantum; WRITE_ONCE(flow->deficit, flow->deficit + q->quantum);
list_move_tail(&flow->flowchain, &q->old_flows); list_move_tail(&flow->flowchain, &q->old_flows);
goto begin; goto begin;
} }
@ -314,7 +315,7 @@ static struct sk_buff *fq_codel_dequeue(struct Qdisc *sch)
goto begin; goto begin;
} }
qdisc_bstats_update(sch, skb); qdisc_bstats_update(sch, skb);
flow->deficit -= qdisc_pkt_len(skb); WRITE_ONCE(flow->deficit, flow->deficit - qdisc_pkt_len(skb));
if (q->cstats.drop_count) { if (q->cstats.drop_count) {
qdisc_tree_reduce_backlog(sch, q->cstats.drop_count, qdisc_tree_reduce_backlog(sch, q->cstats.drop_count,
@ -328,7 +329,7 @@ static struct sk_buff *fq_codel_dequeue(struct Qdisc *sch)
static void fq_codel_flow_purge(struct fq_codel_flow *flow) static void fq_codel_flow_purge(struct fq_codel_flow *flow)
{ {
rtnl_kfree_skbs(flow->head, flow->tail); rtnl_kfree_skbs(flow->head, flow->tail);
flow->head = NULL; WRITE_ONCE(flow->head, NULL);
} }
static void fq_codel_reset(struct Qdisc *sch) static void fq_codel_reset(struct Qdisc *sch)
@ -656,21 +657,21 @@ static int fq_codel_dump_class_stats(struct Qdisc *sch, unsigned long cl,
memset(&xstats, 0, sizeof(xstats)); memset(&xstats, 0, sizeof(xstats));
xstats.type = TCA_FQ_CODEL_XSTATS_CLASS; xstats.type = TCA_FQ_CODEL_XSTATS_CLASS;
xstats.class_stats.deficit = flow->deficit; xstats.class_stats.deficit = READ_ONCE(flow->deficit);
xstats.class_stats.ldelay = xstats.class_stats.ldelay =
codel_time_to_us(flow->cvars.ldelay); codel_time_to_us(READ_ONCE(flow->cvars.ldelay));
xstats.class_stats.count = flow->cvars.count; xstats.class_stats.count = READ_ONCE(flow->cvars.count);
xstats.class_stats.lastcount = flow->cvars.lastcount; xstats.class_stats.lastcount = READ_ONCE(flow->cvars.lastcount);
xstats.class_stats.dropping = flow->cvars.dropping; xstats.class_stats.dropping = READ_ONCE(flow->cvars.dropping);
if (flow->cvars.dropping) { if (xstats.class_stats.dropping) {
codel_tdiff_t delta = flow->cvars.drop_next - codel_tdiff_t delta = READ_ONCE(flow->cvars.drop_next) -
codel_get_time(); codel_get_time();
xstats.class_stats.drop_next = (delta >= 0) ? xstats.class_stats.drop_next = (delta >= 0) ?
codel_time_to_us(delta) : codel_time_to_us(delta) :
-codel_time_to_us(-delta); -codel_time_to_us(-delta);
} }
if (flow->head) { if (READ_ONCE(flow->head)) {
sch_tree_lock(sch); sch_tree_lock(sch);
skb = flow->head; skb = flow->head;
while (skb) { while (skb) {
@ -679,7 +680,7 @@ static int fq_codel_dump_class_stats(struct Qdisc *sch, unsigned long cl,
} }
sch_tree_unlock(sch); sch_tree_unlock(sch);
} }
qs.backlog = q->backlogs[idx]; qs.backlog = READ_ONCE(q->backlogs[idx]);
qs.drops = 0; qs.drops = 0;
} }
if (gnet_stats_copy_queue(d, NULL, &qs, qs.qlen) < 0) if (gnet_stats_copy_queue(d, NULL, &qs, qs.qlen) < 0)