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net: Fix data-races around weight_p and dev_weight_[rt]x_bias.

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While reading weight_p, it can be changed concurrently.  Thus, we need
to add READ_ONCE() to its reader.

Also, dev_[rt]x_weight can be read/written at the same time.  So, we
need to use READ_ONCE() and WRITE_ONCE() for its access.  Moreover, to
use the same weight_p while changing dev_[rt]x_weight, we add a mutex
in proc_do_dev_weight().

Fixes: 3d48b53fb2 ("net: dev_weight: TX/RX orthogonality")
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Kuniyuki Iwashima 2022-08-23 10:46:45 -07:00 • committed by David S. Miller
parent 1227c1771d
commit bf955b5ab8
3 changed files with 11 additions and 8 deletions
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2
net/core/dev.c
View file

@ -5918,7 +5918,7 @@ static int process_backlog(struct napi_struct *napi, int quota)
net_rps_action_and_irq_enable(sd);
}
napi->weight = dev_rx_weight;
napi->weight = READ_ONCE(dev_rx_weight);
while (again) {
struct sk_buff *skb;

15
net/core/sysctl_net_core.c
View file

@ -234,14 +234,17 @@ static int set_default_qdisc(struct ctl_table *table, int write,
static int proc_do_dev_weight(struct ctl_table *table, int write,
void *buffer, size_t *lenp, loff_t *ppos)
{
int ret;
static DEFINE_MUTEX(dev_weight_mutex);
int ret, weight;
mutex_lock(&dev_weight_mutex);
ret = proc_dointvec(table, write, buffer, lenp, ppos);
if (ret != 0)
return ret;
dev_rx_weight = weight_p * dev_weight_rx_bias;
dev_tx_weight = weight_p * dev_weight_tx_bias;
if (!ret && write) {
weight = READ_ONCE(weight_p);
WRITE_ONCE(dev_rx_weight, weight * dev_weight_rx_bias);
WRITE_ONCE(dev_tx_weight, weight * dev_weight_tx_bias);
}
mutex_unlock(&dev_weight_mutex);
return ret;
}

2
net/sched/sch_generic.c
View file

@ -409,7 +409,7 @@ static inline bool qdisc_restart(struct Qdisc *q, int *packets)
void __qdisc_run(struct Qdisc *q)
{
int quota = dev_tx_weight;
int quota = READ_ONCE(dev_tx_weight);
int packets;
while (qdisc_restart(q, &packets)) {