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-rw-r--r--include/net/rps.h125
1 files changed, 125 insertions, 0 deletions
diff --git a/include/net/rps.h b/include/net/rps.h
new file mode 100644
index 0000000000..7660243e90
--- /dev/null
+++ b/include/net/rps.h
@@ -0,0 +1,125 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef _NET_RPS_H
+#define _NET_RPS_H
+
+#include <linux/types.h>
+#include <linux/static_key.h>
+#include <net/sock.h>
+#include <net/hotdata.h>
+
+#ifdef CONFIG_RPS
+
+extern struct static_key_false rps_needed;
+extern struct static_key_false rfs_needed;
+
+/*
+ * This structure holds an RPS map which can be of variable length. The
+ * map is an array of CPUs.
+ */
+struct rps_map {
+ unsigned int len;
+ struct rcu_head rcu;
+ u16 cpus[];
+};
+#define RPS_MAP_SIZE(_num) (sizeof(struct rps_map) + ((_num) * sizeof(u16)))
+
+/*
+ * The rps_dev_flow structure contains the mapping of a flow to a CPU, the
+ * tail pointer for that CPU's input queue at the time of last enqueue, and
+ * a hardware filter index.
+ */
+struct rps_dev_flow {
+ u16 cpu;
+ u16 filter;
+ unsigned int last_qtail;
+};
+#define RPS_NO_FILTER 0xffff
+
+/*
+ * The rps_dev_flow_table structure contains a table of flow mappings.
+ */
+struct rps_dev_flow_table {
+ unsigned int mask;
+ struct rcu_head rcu;
+ struct rps_dev_flow flows[];
+};
+#define RPS_DEV_FLOW_TABLE_SIZE(_num) (sizeof(struct rps_dev_flow_table) + \
+ ((_num) * sizeof(struct rps_dev_flow)))
+
+/*
+ * The rps_sock_flow_table contains mappings of flows to the last CPU
+ * on which they were processed by the application (set in recvmsg).
+ * Each entry is a 32bit value. Upper part is the high-order bits
+ * of flow hash, lower part is CPU number.
+ * rps_cpu_mask is used to partition the space, depending on number of
+ * possible CPUs : rps_cpu_mask = roundup_pow_of_two(nr_cpu_ids) - 1
+ * For example, if 64 CPUs are possible, rps_cpu_mask = 0x3f,
+ * meaning we use 32-6=26 bits for the hash.
+ */
+struct rps_sock_flow_table {
+ u32 mask;
+
+ u32 ents[] ____cacheline_aligned_in_smp;
+};
+#define RPS_SOCK_FLOW_TABLE_SIZE(_num) (offsetof(struct rps_sock_flow_table, ents[_num]))
+
+#define RPS_NO_CPU 0xffff
+
+static inline void rps_record_sock_flow(struct rps_sock_flow_table *table,
+ u32 hash)
+{
+ unsigned int index = hash & table->mask;
+ u32 val = hash & ~net_hotdata.rps_cpu_mask;
+
+ /* We only give a hint, preemption can change CPU under us */
+ val |= raw_smp_processor_id();
+
+ /* The following WRITE_ONCE() is paired with the READ_ONCE()
+ * here, and another one in get_rps_cpu().
+ */
+ if (READ_ONCE(table->ents[index]) != val)
+ WRITE_ONCE(table->ents[index], val);
+}
+
+#endif /* CONFIG_RPS */
+
+static inline void sock_rps_record_flow_hash(__u32 hash)
+{
+#ifdef CONFIG_RPS
+ struct rps_sock_flow_table *sock_flow_table;
+
+ if (!hash)
+ return;
+ rcu_read_lock();
+ sock_flow_table = rcu_dereference(net_hotdata.rps_sock_flow_table);
+ if (sock_flow_table)
+ rps_record_sock_flow(sock_flow_table, hash);
+ rcu_read_unlock();
+#endif
+}
+
+static inline void sock_rps_record_flow(const struct sock *sk)
+{
+#ifdef CONFIG_RPS
+ if (static_branch_unlikely(&rfs_needed)) {
+ /* Reading sk->sk_rxhash might incur an expensive cache line
+ * miss.
+ *
+ * TCP_ESTABLISHED does cover almost all states where RFS
+ * might be useful, and is cheaper [1] than testing :
+ * IPv4: inet_sk(sk)->inet_daddr
+ * IPv6: ipv6_addr_any(&sk->sk_v6_daddr)
+ * OR an additional socket flag
+ * [1] : sk_state and sk_prot are in the same cache line.
+ */
+ if (sk->sk_state == TCP_ESTABLISHED) {
+ /* This READ_ONCE() is paired with the WRITE_ONCE()
+ * from sock_rps_save_rxhash() and sock_rps_reset_rxhash().
+ */
+ sock_rps_record_flow_hash(READ_ONCE(sk->sk_rxhash));
+ }
+ }
+#endif
+}
+
+#endif /* _NET_RPS_H */