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Commit 74d5d257 authored by Eric Dumazet's avatar Eric Dumazet Committed by Greg Kroah-Hartman
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net_sched: sch_sfq: annotate data-races around q->perturb_period 



[ Upstream commit a17ef9e6c2c1cf0fc6cd6ca6a9ce525c67d1da7f ]

sfq_perturbation() reads q->perturb_period locklessly.
Add annotations to fix potential issues.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reviewed-by: default avatarSimon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/20240430180015.3111398-1-edumazet@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
[ Harshit: Backport to 5.4.y, conflicts resolved due to missing commit:
  d636fc5dd692 ("net: sched: add rcu annotations around
  qdisc->qdisc_sleeping")in 5.4.y ]
Signed-off-by: default avatarHarshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 4a1b82ee

net/sched/sch_sfq.c

+9 −4
Original line number Diff line number Diff line
@@ -611,6 +611,7 @@ static void sfq_perturbation(struct timer_list *t) 
	struct Qdisc *sch = q->sch;

	spinlock_t *root_lock = qdisc_lock(qdisc_root_sleeping(sch));

	siphash_key_t nkey;

	int period;



	get_random_bytes(&nkey, sizeof(nkey));

	spin_lock(root_lock);
@@ -619,8 +620,12 @@ static void sfq_perturbation(struct timer_list *t) 
		sfq_rehash(sch);

	spin_unlock(root_lock);



	if (q->perturb_period)

		mod_timer(&q->perturb_timer, jiffies + q->perturb_period);

	/* q->perturb_period can change under us from

	 * sfq_change() and sfq_destroy().

	 */

	period = READ_ONCE(q->perturb_period);

	if (period)

		mod_timer(&q->perturb_timer, jiffies + period);

}



static int sfq_change(struct Qdisc *sch, struct nlattr *opt)
@@ -662,7 +667,7 @@ static int sfq_change(struct Qdisc *sch, struct nlattr *opt) 
		q->quantum = ctl->quantum;

		q->scaled_quantum = SFQ_ALLOT_SIZE(q->quantum);

	}

	q->perturb_period = ctl->perturb_period * HZ;

	WRITE_ONCE(q->perturb_period, ctl->perturb_period * HZ);

	if (ctl->flows)

		q->maxflows = min_t(u32, ctl->flows, SFQ_MAX_FLOWS);

	if (ctl->divisor) {
@@ -724,7 +729,7 @@ static void sfq_destroy(struct Qdisc *sch) 
	struct sfq_sched_data *q = qdisc_priv(sch);



	tcf_block_put(q->block);

	q->perturb_period = 0;

	WRITE_ONCE(q->perturb_period, 0);

	del_timer_sync(&q->perturb_timer);

	sfq_free(q->ht);

	sfq_free(q->slots);