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Merge branch 'rps-misc-changes'

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Eric Dumazet says:

====================
rps: misc changes

Minor changes in rps:

skb_flow_limit() is probably unused these days,
and data-races are quite theoretical.
====================

Link: https://patch.msgid.link/20250407163602.170356-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Jakub Kicinski 2025-04-08 12:30:56 -07:00
commit 05b8f502f4
5 changed files with 21 additions and 15 deletions
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5
include/net/rps.h
View File

@ -57,9 +57,10 @@ struct rps_dev_flow_table {
* meaning we use 32-6=26 bits for the hash.
*/
struct rps_sock_flow_table {
u32 mask;
struct rcu_head rcu;
u32 mask;
u32 ents[] ____cacheline_aligned_in_smp;
u32 ents[] ____cacheline_aligned_in_smp;
};
#define RPS_SOCK_FLOW_TABLE_SIZE(_num) (offsetof(struct rps_sock_flow_table, ents[_num]))

11
net/core/dev.c
View File

@ -4953,7 +4953,8 @@ static void rps_trigger_softirq(void *data)
struct softnet_data *sd = data;
____napi_schedule(sd, &sd->backlog);
sd->received_rps++;
/* Pairs with READ_ONCE() in softnet_seq_show() */
WRITE_ONCE(sd->received_rps, sd->received_rps + 1);
}
#endif /* CONFIG_RPS */
@ -5038,7 +5039,7 @@ static bool skb_flow_limit(struct sk_buff *skb, unsigned int qlen)
rcu_read_lock();
fl = rcu_dereference(sd->flow_limit);
if (fl) {
new_flow = skb_get_hash(skb) & (fl->num_buckets - 1);
new_flow = hash_32(skb_get_hash(skb), fl->log_buckets);
old_flow = fl->history[fl->history_head];
fl->history[fl->history_head] = new_flow;
@ -5049,7 +5050,8 @@ static bool skb_flow_limit(struct sk_buff *skb, unsigned int qlen)
fl->buckets[old_flow]--;
if (++fl->buckets[new_flow] > (FLOW_LIMIT_HISTORY >> 1)) {
fl->count++;
/* Pairs with READ_ONCE() in softnet_seq_show() */
WRITE_ONCE(fl->count, fl->count + 1);
rcu_read_unlock();
return true;
}
@ -7522,7 +7524,8 @@ static __latent_entropy void net_rx_action(void)
*/
if (unlikely(budget <= 0 ||
time_after_eq(jiffies, time_limit))) {
sd->time_squeeze++;
/* Pairs with READ_ONCE() in softnet_seq_show() */
WRITE_ONCE(sd->time_squeeze, sd->time_squeeze + 1);
break;
}
}

5
net/core/dev.h
View File

@ -15,8 +15,9 @@ struct cpumask;
/* Random bits of netdevice that don't need to be exposed */
#define FLOW_LIMIT_HISTORY (1 << 7) /* must be ^2 and !overflow buckets */
struct sd_flow_limit {
u64 count;
unsigned int num_buckets;
struct rcu_head rcu;
unsigned int count;
u8 log_buckets;
unsigned int history_head;
u16 history[FLOW_LIMIT_HISTORY];
u8 buckets[];

9
net/core/net-procfs.c
View File

@ -132,8 +132,9 @@ static int softnet_seq_show(struct seq_file *seq, void *v)
rcu_read_lock();
fl = rcu_dereference(sd->flow_limit);
/* Pairs with WRITE_ONCE() in skb_flow_limit() */
if (fl)
flow_limit_count = fl->count;
flow_limit_count = READ_ONCE(fl->count);
rcu_read_unlock();
#endif
@ -144,11 +145,11 @@ static int softnet_seq_show(struct seq_file *seq, void *v)
seq_printf(seq,
"%08x %08x %08x %08x %08x %08x %08x %08x %08x %08x %08x %08x %08x "
"%08x %08x\n",
sd->processed, atomic_read(&sd->dropped),
sd->time_squeeze, 0,
READ_ONCE(sd->processed), atomic_read(&sd->dropped),
READ_ONCE(sd->time_squeeze), 0,
0, 0, 0, 0, /* was fastroute */
0, /* was cpu_collision */
sd->received_rps, flow_limit_count,
READ_ONCE(sd->received_rps), flow_limit_count,
input_qlen + process_qlen, (int)seq->index,
input_qlen, process_qlen);
return 0;

6
net/core/sysctl_net_core.c
View File

@ -201,7 +201,7 @@ static int rps_sock_flow_sysctl(const struct ctl_table *table, int write,
if (orig_sock_table) {
static_branch_dec(&rps_needed);
static_branch_dec(&rfs_needed);
kvfree_rcu_mightsleep(orig_sock_table);
kvfree_rcu(orig_sock_table, rcu);
}
}
}
@ -239,7 +239,7 @@ static int flow_limit_cpu_sysctl(const struct ctl_table *table, int write,
lockdep_is_held(&flow_limit_update_mutex));
if (cur && !cpumask_test_cpu(i, mask)) {
RCU_INIT_POINTER(sd->flow_limit, NULL);
kfree_rcu_mightsleep(cur);
kfree_rcu(cur, rcu);
} else if (!cur && cpumask_test_cpu(i, mask)) {
cur = kzalloc_node(len, GFP_KERNEL,
cpu_to_node(i));
@ -248,7 +248,7 @@ static int flow_limit_cpu_sysctl(const struct ctl_table *table, int write,
ret = -ENOMEM;
goto write_unlock;
}
cur->num_buckets = netdev_flow_limit_table_len;
cur->log_buckets = ilog2(netdev_flow_limit_table_len);
rcu_assign_pointer(sd->flow_limit, cur);
}
}