commit a17ef9e6c2c1cf0fc6cd6ca6a9ce525c67d1da7f upstream.
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 --- net/sched/sch_sfq.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/net/sched/sch_sfq.c b/net/sched/sch_sfq.c index f8e569f79f1367563bf92793dbd2a9c0a4ce957b..d6299eb12a8164bcaa0594d3ac2829531bfac588 100644 --- a/net/sched/sch_sfq.c +++ b/net/sched/sch_sfq.c @@ -608,6 +608,7 @@ 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); @@ -616,8 +617,12 @@ 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) @@ -659,7 +664,7 @@ 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) { @@ -721,7 +726,7 @@ 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);