diff mbox series

[net-next,1/2] inet: remove icsk_ack.blocked

Message ID 20200930125457.1579469-2-eric.dumazet@gmail.com
State New
Headers show
Series tcp: exponential backoff in tcp_send_ack() | expand

Commit Message

Eric Dumazet Sept. 30, 2020, 12:54 p.m. UTC 
From: Eric Dumazet <edumazet@google.com>

TCP has been using it to work around the possibility of tcp_delack_timer()
finding the socket owned by user.

After commit 6f458dfb4092 ("tcp: improve latencies of timer triggered events")
we added TCP_DELACK_TIMER_DEFERRED atomic bit for more immediate recovery,
so we can get rid of icsk_ack.blocked

This frees space that following patch will reuse.

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 include/net/inet_connection_sock.h | 4 ++--
 net/dccp/timer.c                   | 1 -
 net/ipv4/inet_connection_sock.c    | 2 +-
 net/ipv4/tcp.c                     | 6 ++----
 net/ipv4/tcp_output.c              | 7 ++-----
 net/ipv4/tcp_timer.c               | 1 -
 6 files changed, 7 insertions(+), 14 deletions(-)

Comments

Soheil Hassas Yeganeh Sept. 30, 2020, 1:45 p.m. UTC | #1 
On Wed, Sep 30, 2020 at 8:55 AM Eric Dumazet <eric.dumazet@gmail.com> wrote:
>

> From: Eric Dumazet <edumazet@google.com>

>

> TCP has been using it to work around the possibility of tcp_delack_timer()

> finding the socket owned by user.

>

> After commit 6f458dfb4092 ("tcp: improve latencies of timer triggered events")

> we added TCP_DELACK_TIMER_DEFERRED atomic bit for more immediate recovery,

> so we can get rid of icsk_ack.blocked

>

> This frees space that following patch will reuse.

>

> Signed-off-by: Eric Dumazet <edumazet@google.com>


Acked-by: Soheil Hassas Yeganeh <soheil@google.com>


> ---

>  include/net/inet_connection_sock.h | 4 ++--

>  net/dccp/timer.c                   | 1 -

>  net/ipv4/inet_connection_sock.c    | 2 +-

>  net/ipv4/tcp.c                     | 6 ++----

>  net/ipv4/tcp_output.c              | 7 ++-----

>  net/ipv4/tcp_timer.c               | 1 -

>  6 files changed, 7 insertions(+), 14 deletions(-)

>

> diff --git a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h

> index dc763ca9413cc9c6279a59f9d1776cf2dbb1e853..79875f976190750819948425e63dd0309c699050 100644

> --- a/include/net/inet_connection_sock.h

> +++ b/include/net/inet_connection_sock.h

> @@ -110,7 +110,7 @@ struct inet_connection_sock {

>                 __u8              pending;       /* ACK is pending                         */

>                 __u8              quick;         /* Scheduled number of quick acks         */

>                 __u8              pingpong;      /* The session is interactive             */

> -               __u8              blocked;       /* Delayed ACK was blocked by socket lock */

> +               /* one byte hole. */

>                 __u32             ato;           /* Predicted tick of soft clock           */

>                 unsigned long     timeout;       /* Currently scheduled timeout            */

>                 __u32             lrcvtime;      /* timestamp of last received data packet */

> @@ -198,7 +198,7 @@ static inline void inet_csk_clear_xmit_timer(struct sock *sk, const int what)

>                 sk_stop_timer(sk, &icsk->icsk_retransmit_timer);

>  #endif

>         } else if (what == ICSK_TIME_DACK) {

> -               icsk->icsk_ack.blocked = icsk->icsk_ack.pending = 0;

> +               icsk->icsk_ack.pending = 0;

>  #ifdef INET_CSK_CLEAR_TIMERS

>                 sk_stop_timer(sk, &icsk->icsk_delack_timer);

>  #endif

> diff --git a/net/dccp/timer.c b/net/dccp/timer.c

> index 927c796d76825439a35c4deb3fb2e45e4313f9b3..a934d293237366aeca87bd3c32241880639291c5 100644

> --- a/net/dccp/timer.c

> +++ b/net/dccp/timer.c

> @@ -176,7 +176,6 @@ static void dccp_delack_timer(struct timer_list *t)

>         bh_lock_sock(sk);

>         if (sock_owned_by_user(sk)) {

>                 /* Try again later. */

> -               icsk->icsk_ack.blocked = 1;

>                 __NET_INC_STATS(sock_net(sk), LINUX_MIB_DELAYEDACKLOCKED);

>                 sk_reset_timer(sk, &icsk->icsk_delack_timer,

>                                jiffies + TCP_DELACK_MIN);

> diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c

> index b457dd2d6c75b2f63bc7849474ac909adb14d603..4148f5f78f313cde1e0596b9eb3696df16e3f990 100644

> --- a/net/ipv4/inet_connection_sock.c

> +++ b/net/ipv4/inet_connection_sock.c

> @@ -564,7 +564,7 @@ void inet_csk_clear_xmit_timers(struct sock *sk)

>  {

>         struct inet_connection_sock *icsk = inet_csk(sk);

>

> -       icsk->icsk_pending = icsk->icsk_ack.pending = icsk->icsk_ack.blocked = 0;

> +       icsk->icsk_pending = icsk->icsk_ack.pending = 0;

>

>         sk_stop_timer(sk, &icsk->icsk_retransmit_timer);

>         sk_stop_timer(sk, &icsk->icsk_delack_timer);

> diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c

> index 2a8bfa89a5159837e3687e4e0f8cddba7fe54899..ed2805564424a90f003eed867bbed7f5ac4ae833 100644

> --- a/net/ipv4/tcp.c

> +++ b/net/ipv4/tcp.c

> @@ -1538,10 +1538,8 @@ void tcp_cleanup_rbuf(struct sock *sk, int copied)

>

>         if (inet_csk_ack_scheduled(sk)) {

>                 const struct inet_connection_sock *icsk = inet_csk(sk);

> -                  /* Delayed ACKs frequently hit locked sockets during bulk

> -                   * receive. */

> -               if (icsk->icsk_ack.blocked ||

> -                   /* Once-per-two-segments ACK was not sent by tcp_input.c */

> +

> +               if (/* Once-per-two-segments ACK was not sent by tcp_input.c */

>                     tp->rcv_nxt - tp->rcv_wup > icsk->icsk_ack.rcv_mss ||

>                     /*

>                      * If this read emptied read buffer, we send ACK, if

> diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c

> index 386978dcd318d84af486d0d1a5bb1786f4a493cf..6bd4e383030ea20441332a30e98fbda8cd90f84a 100644

> --- a/net/ipv4/tcp_output.c

> +++ b/net/ipv4/tcp_output.c

> @@ -3911,11 +3911,8 @@ void tcp_send_delayed_ack(struct sock *sk)

>

>         /* Use new timeout only if there wasn't a older one earlier. */

>         if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) {

> -               /* If delack timer was blocked or is about to expire,

> -                * send ACK now.

> -                */

> -               if (icsk->icsk_ack.blocked ||

> -                   time_before_eq(icsk->icsk_ack.timeout, jiffies + (ato >> 2))) {

> +               /* If delack timer is about to expire, send ACK now. */

> +               if (time_before_eq(icsk->icsk_ack.timeout, jiffies + (ato >> 2))) {

>                         tcp_send_ack(sk);

>                         return;

>                 }

> diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c

> index 0c08c420fbc21a98dedf72148ea2a6f85bf3ff7a..6c62b9ea1320d9bbd26ed86b9f41de02fee6c491 100644

> --- a/net/ipv4/tcp_timer.c

> +++ b/net/ipv4/tcp_timer.c

> @@ -331,7 +331,6 @@ static void tcp_delack_timer(struct timer_list *t)

>         if (!sock_owned_by_user(sk)) {

>                 tcp_delack_timer_handler(sk);

>         } else {

> -               icsk->icsk_ack.blocked = 1;

>                 __NET_INC_STATS(sock_net(sk), LINUX_MIB_DELAYEDACKLOCKED);

>                 /* deleguate our work to tcp_release_cb() */

>                 if (!test_and_set_bit(TCP_DELACK_TIMER_DEFERRED, &sk->sk_tsq_flags))

> --

> 2.28.0.806.g8561365e88-goog

>
diff mbox series

Patch

diff --git a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h
index dc763ca9413cc9c6279a59f9d1776cf2dbb1e853..79875f976190750819948425e63dd0309c699050 100644
--- a/include/net/inet_connection_sock.h
+++ b/include/net/inet_connection_sock.h
@@ -110,7 +110,7 @@  struct inet_connection_sock {
 		__u8		  pending;	 /* ACK is pending			   */
 		__u8		  quick;	 /* Scheduled number of quick acks	   */
 		__u8		  pingpong;	 /* The session is interactive		   */
-		__u8		  blocked;	 /* Delayed ACK was blocked by socket lock */
+		/* one byte hole. */
 		__u32		  ato;		 /* Predicted tick of soft clock	   */
 		unsigned long	  timeout;	 /* Currently scheduled timeout		   */
 		__u32		  lrcvtime;	 /* timestamp of last received data packet */
@@ -198,7 +198,7 @@  static inline void inet_csk_clear_xmit_timer(struct sock *sk, const int what)
 		sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
 #endif
 	} else if (what == ICSK_TIME_DACK) {
-		icsk->icsk_ack.blocked = icsk->icsk_ack.pending = 0;
+		icsk->icsk_ack.pending = 0;
 #ifdef INET_CSK_CLEAR_TIMERS
 		sk_stop_timer(sk, &icsk->icsk_delack_timer);
 #endif
diff --git a/net/dccp/timer.c b/net/dccp/timer.c
index 927c796d76825439a35c4deb3fb2e45e4313f9b3..a934d293237366aeca87bd3c32241880639291c5 100644
--- a/net/dccp/timer.c
+++ b/net/dccp/timer.c
@@ -176,7 +176,6 @@  static void dccp_delack_timer(struct timer_list *t)
 	bh_lock_sock(sk);
 	if (sock_owned_by_user(sk)) {
 		/* Try again later. */
-		icsk->icsk_ack.blocked = 1;
 		__NET_INC_STATS(sock_net(sk), LINUX_MIB_DELAYEDACKLOCKED);
 		sk_reset_timer(sk, &icsk->icsk_delack_timer,
 			       jiffies + TCP_DELACK_MIN);
diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index b457dd2d6c75b2f63bc7849474ac909adb14d603..4148f5f78f313cde1e0596b9eb3696df16e3f990 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -564,7 +564,7 @@  void inet_csk_clear_xmit_timers(struct sock *sk)
 {
 	struct inet_connection_sock *icsk = inet_csk(sk);
 
-	icsk->icsk_pending = icsk->icsk_ack.pending = icsk->icsk_ack.blocked = 0;
+	icsk->icsk_pending = icsk->icsk_ack.pending = 0;
 
 	sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
 	sk_stop_timer(sk, &icsk->icsk_delack_timer);
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 2a8bfa89a5159837e3687e4e0f8cddba7fe54899..ed2805564424a90f003eed867bbed7f5ac4ae833 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1538,10 +1538,8 @@  void tcp_cleanup_rbuf(struct sock *sk, int copied)
 
 	if (inet_csk_ack_scheduled(sk)) {
 		const struct inet_connection_sock *icsk = inet_csk(sk);
-		   /* Delayed ACKs frequently hit locked sockets during bulk
-		    * receive. */
-		if (icsk->icsk_ack.blocked ||
-		    /* Once-per-two-segments ACK was not sent by tcp_input.c */
+
+		if (/* Once-per-two-segments ACK was not sent by tcp_input.c */
 		    tp->rcv_nxt - tp->rcv_wup > icsk->icsk_ack.rcv_mss ||
 		    /*
 		     * If this read emptied read buffer, we send ACK, if
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 386978dcd318d84af486d0d1a5bb1786f4a493cf..6bd4e383030ea20441332a30e98fbda8cd90f84a 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -3911,11 +3911,8 @@  void tcp_send_delayed_ack(struct sock *sk)
 
 	/* Use new timeout only if there wasn't a older one earlier. */
 	if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) {
-		/* If delack timer was blocked or is about to expire,
-		 * send ACK now.
-		 */
-		if (icsk->icsk_ack.blocked ||
-		    time_before_eq(icsk->icsk_ack.timeout, jiffies + (ato >> 2))) {
+		/* If delack timer is about to expire, send ACK now. */
+		if (time_before_eq(icsk->icsk_ack.timeout, jiffies + (ato >> 2))) {
 			tcp_send_ack(sk);
 			return;
 		}
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index 0c08c420fbc21a98dedf72148ea2a6f85bf3ff7a..6c62b9ea1320d9bbd26ed86b9f41de02fee6c491 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -331,7 +331,6 @@  static void tcp_delack_timer(struct timer_list *t)
 	if (!sock_owned_by_user(sk)) {
 		tcp_delack_timer_handler(sk);
 	} else {
-		icsk->icsk_ack.blocked = 1;
 		__NET_INC_STATS(sock_net(sk), LINUX_MIB_DELAYEDACKLOCKED);
 		/* deleguate our work to tcp_release_cb() */
 		if (!test_and_set_bit(TCP_DELACK_TIMER_DEFERRED, &sk->sk_tsq_flags))