tcp: introduce tcp_under_memory_pressure()

Introduce an optimized version of sk_under_memory_pressure()
for TCP. Our intent is to use it in fast paths.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 15 insertions, 7 deletions

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 841691a296dc..0d85223efa4c 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -286,6 +286,14 @@ extern atomic_long_t tcp_memory_allocated;
 extern struct percpu_counter tcp_sockets_allocated;
 extern int tcp_memory_pressure;
 
+/* optimized version of sk_under_memory_pressure() for TCP sockets */
+static inline bool tcp_under_memory_pressure(const struct sock *sk)
+{
+        if (mem_cgroup_sockets_enabled && sk->sk_cgrp)
+                return !!sk->sk_cgrp->memory_pressure;
+
+        return tcp_memory_pressure;
+}
 /*
  * The next routines deal with comparing 32 bit unsigned ints
  * and worry about wraparound (automatic with unsigned arithmetic).
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index cf8b20ff6658..093779f7e893 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -359,7 +359,7 @@ static void tcp_grow_window(struct sock *sk, const struct sk_buff *skb)
         /* Check #1 */
         if (tp->rcv_ssthresh < tp->window_clamp &&
             (int)tp->rcv_ssthresh < tcp_space(sk) &&
-            !sk_under_memory_pressure(sk)) {
+            !tcp_under_memory_pressure(sk)) {
                 int incr;
 
                 /* Check #2. Increase window, if skb with such overhead
@@ -446,7 +446,7 @@ static void tcp_clamp_window(struct sock *sk)
 
         if (sk->sk_rcvbuf < sysctl_tcp_rmem[2] &&
             !(sk->sk_userlocks & SOCK_RCVBUF_LOCK) &&
-            !sk_under_memory_pressure(sk) &&
+            !tcp_under_memory_pressure(sk) &&
             sk_memory_allocated(sk) < sk_prot_mem_limits(sk, 0)) {
                 sk->sk_rcvbuf = min(atomic_read(&sk->sk_rmem_alloc),
                                     sysctl_tcp_rmem[2]);
@@ -4781,7 +4781,7 @@ static int tcp_prune_queue(struct sock *sk)
 
         if (atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf)
                 tcp_clamp_window(sk);
-        else if (sk_under_memory_pressure(sk))
+        else if (tcp_under_memory_pressure(sk))
                 tp->rcv_ssthresh = min(tp->rcv_ssthresh, 4U * tp->advmss);
 
         tcp_collapse_ofo_queue(sk);
@@ -4825,7 +4825,7 @@ static bool tcp_should_expand_sndbuf(const struct sock *sk)
                 return false;
 
         /* If we are under global TCP memory pressure, do not expand.  */
-        if (sk_under_memory_pressure(sk))
+        if (tcp_under_memory_pressure(sk))
                 return false;
 
         /* If we are under soft global TCP memory pressure, do not expand.  */
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index bac1a950d087..08c2cc40b26d 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2392,7 +2392,7 @@ u32 __tcp_select_window(struct sock *sk)
         if (free_space < (full_space >> 1)) {
                 icsk->icsk_ack.quick = 0;
 
-                if (sk_under_memory_pressure(sk))
+                if (tcp_under_memory_pressure(sk))
                         tp->rcv_ssthresh = min(tp->rcv_ssthresh,
                                                4U * tp->advmss);
 
@@ -2843,7 +2843,7 @@ void tcp_send_fin(struct sock *sk)
          * Note: in the latter case, FIN packet will be sent after a timeout,
          * as TCP stack thinks it has already been transmitted.
          */
-        if (tskb && (tcp_send_head(sk) || sk_under_memory_pressure(sk))) {
+        if (tskb && (tcp_send_head(sk) || tcp_under_memory_pressure(sk))) {
 coalesce:
                 TCP_SKB_CB(tskb)->tcp_flags |= TCPHDR_FIN;
                 TCP_SKB_CB(tskb)->end_seq++;
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index 65bf670e8714..5b752f58a900 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -247,7 +247,7 @@ void tcp_delack_timer_handler(struct sock *sk)
         }
 
 out:
-        if (sk_under_memory_pressure(sk))
+        if (tcp_under_memory_pressure(sk))
                 sk_mem_reclaim(sk);
 }