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net_sched: sch_sfq: annotate data-races around q->perturb_period

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[ Upstream commit a17ef9e6c2c1cf0fc6cd6ca6a9ce525c67d1da7f ]

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

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/20240430180015.3111398-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
[ Harshit: Backport to 5.10.y, conflicts resolved due to missing commit:
  d636fc5dd692 ("net: sched: add rcu annotations around qdisc->qdisc_sleeping")
  in 5.10.y ]
Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Eric Dumazet
2025-06-15 10:51:49 -07:00
committed by Greg Kroah-Hartman
parent 458b8e2d6a
commit b010c36371
1 changed files with 9 additions and 4 deletions
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13
net/sched/sch_sfq.c
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@@ -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);