5.4-stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet edumazet@google.com
[ 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 5.4.y, conflicts resolved due to missing commit: d636fc5dd692 ("net: sched: add rcu annotations around qdisc->qdisc_sleeping")in 5.4.y ] Signed-off-by: Harshit Mogalapalli harshit.m.mogalapalli@oracle.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/sched/sch_sfq.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-)
--- a/net/sched/sch_sfq.c +++ b/net/sched/sch_sfq.c @@ -611,6 +611,7 @@ static void sfq_perturbation(struct time 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 time 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, 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 *sc 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);