diff mbox series

[net-next,1/2] tcp: record last received ipv6 flowlabel

Message ID 20230927182747.2005960-1-morleyd.kernel@gmail.com (mailing list archive)
State Changes Requested
Delegated to: Netdev Maintainers
Headers show
Series [net-next,1/2] tcp: record last received ipv6 flowlabel | expand

Checks

Context Check Description
netdev/series_format success Single patches do not need cover letters
netdev/tree_selection success Clearly marked for net-next, async
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit fail Errors and warnings before: 3379 this patch: 3381
netdev/cc_maintainers warning 2 maintainers not CCed: pabeni@redhat.com dsahern@kernel.org
netdev/build_clang fail Errors and warnings before: 1560 this patch: 1562
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn fail Errors and warnings before: 3629 this patch: 3631
netdev/checkpatch warning CHECK: spaces preferred around that '<<' (ctx:VxV) WARNING: line length of 84 exceeds 80 columns WARNING: line length of 93 exceeds 80 columns WARNING: line length of 97 exceeds 80 columns
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

David Morley Sept. 27, 2023, 6:27 p.m. UTC 
From: David Morley <morleyd@google.com>

In order to better estimate whether a data packet has been
retransmitted or is the result of a TLP, we save the last received
ipv6 flowlabel.

To make space for this field we resize the "ato" field in
inet_connection_sock as the current value of TCP_DELACK_MAX can be
fully contained in 8 bits and add a compile_time_assert ensuring this
field is the required size.

Signed-off-by: David Morley <morleyd@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Tested-by: David Morley <morleyd@google.com>
---
 include/net/inet_connection_sock.h |  5 ++++-
 include/net/tcp.h                  |  2 ++
 net/ipv4/tcp_input.c               | 15 +++++++++++++++
 net/ipv4/tcp_timer.c               |  2 +-
 4 files changed, 22 insertions(+), 2 deletions(-)

Comments

Eric Dumazet Sept. 29, 2023, 12:52 a.m. UTC | #1 
On Wed, Sep 27, 2023 at 8:28 PM David Morley <morleyd.kernel@gmail.com> wrote:
>
> From: David Morley <morleyd@google.com>
>
> In order to better estimate whether a data packet has been
> retransmitted or is the result of a TLP, we save the last received
> ipv6 flowlabel.
>
> To make space for this field we resize the "ato" field in
> inet_connection_sock as the current value of TCP_DELACK_MAX can be
> fully contained in 8 bits and add a compile_time_assert ensuring this
> field is the required size.
>
> Signed-off-by: David Morley <morleyd@google.com>
> Signed-off-by: Neal Cardwell <ncardwell@google.com>
> Signed-off-by: Yuchung Cheng <ycheng@google.com>
> Tested-by: David Morley <morleyd@google.com>

Reviewed-by: Eric Dumazet <edumazet@google.com>
kernel test robot Sept. 29, 2023, 5:57 a.m. UTC | #2 
Hi David,

kernel test robot noticed the following build warnings:

[auto build test WARNING on net-next/main]

url:    https://github.com/intel-lab-lkp/linux/commits/David-Morley/tcp-change-data-receiver-flowlabel-after-one-dup/20230928-022955
base:   net-next/main
patch link:    https://lore.kernel.org/r/20230927182747.2005960-1-morleyd.kernel%40gmail.com
patch subject: [PATCH net-next 1/2] tcp: record last received ipv6 flowlabel
config: x86_64-rhel-8.3-rust (https://download.01.org/0day-ci/archive/20230929/202309291312.vJyV8G9L-lkp@intel.com/config)
compiler: clang version 16.0.4 (https://github.com/llvm/llvm-project.git ae42196bc493ffe877a7e3dff8be32035dea4d07)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20230929/202309291312.vJyV8G9L-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202309291312.vJyV8G9L-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> net/dccp/timer.c:199:25: warning: comparison of distinct pointer types ('typeof (icsk->icsk_ack.ato << 1) *' (aka 'int *') and 'typeof (icsk->icsk_rto) *' (aka 'unsigned int *')) [-Wcompare-distinct-pointer-types]
                           icsk->icsk_ack.ato = min(icsk->icsk_ack.ato << 1,
                                                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/minmax.h:68:19: note: expanded from macro 'min'
   #define min(x, y)       __careful_cmp(x, y, <)
                           ^~~~~~~~~~~~~~~~~~~~~~
   include/linux/minmax.h:37:24: note: expanded from macro '__careful_cmp'
           __builtin_choose_expr(__safe_cmp(x, y), \
                                 ^~~~~~~~~~~~~~~~
   include/linux/minmax.h:27:4: note: expanded from macro '__safe_cmp'
                   (__typecheck(x, y) && __no_side_effects(x, y))
                    ^~~~~~~~~~~~~~~~~
   include/linux/minmax.h:21:28: note: expanded from macro '__typecheck'
           (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1)))
                      ~~~~~~~~~~~~~~ ^  ~~~~~~~~~~~~~~
   1 warning generated.


vim +199 net/dccp/timer.c

4ed800d02cfb63 Gerrit Renker 2006-11-13  168  
4ed800d02cfb63 Gerrit Renker 2006-11-13  169  /* This is the same as tcp_delack_timer, sans prequeue & mem_reclaim stuff */
59f379f9046a9e Kees Cook     2017-10-16  170  static void dccp_delack_timer(struct timer_list *t)
4ed800d02cfb63 Gerrit Renker 2006-11-13  171  {
59f379f9046a9e Kees Cook     2017-10-16  172  	struct inet_connection_sock *icsk =
59f379f9046a9e Kees Cook     2017-10-16  173  			from_timer(icsk, t, icsk_delack_timer);
59f379f9046a9e Kees Cook     2017-10-16  174  	struct sock *sk = &icsk->icsk_inet.sk;
4ed800d02cfb63 Gerrit Renker 2006-11-13  175  
4ed800d02cfb63 Gerrit Renker 2006-11-13  176  	bh_lock_sock(sk);
4ed800d02cfb63 Gerrit Renker 2006-11-13  177  	if (sock_owned_by_user(sk)) {
4ed800d02cfb63 Gerrit Renker 2006-11-13  178  		/* Try again later. */
02a1d6e7a6bb02 Eric Dumazet  2016-04-27  179  		__NET_INC_STATS(sock_net(sk), LINUX_MIB_DELAYEDACKLOCKED);
4ed800d02cfb63 Gerrit Renker 2006-11-13  180  		sk_reset_timer(sk, &icsk->icsk_delack_timer,
4ed800d02cfb63 Gerrit Renker 2006-11-13  181  			       jiffies + TCP_DELACK_MIN);
4ed800d02cfb63 Gerrit Renker 2006-11-13  182  		goto out;
4ed800d02cfb63 Gerrit Renker 2006-11-13  183  	}
4ed800d02cfb63 Gerrit Renker 2006-11-13  184  
4ed800d02cfb63 Gerrit Renker 2006-11-13  185  	if (sk->sk_state == DCCP_CLOSED ||
4ed800d02cfb63 Gerrit Renker 2006-11-13  186  	    !(icsk->icsk_ack.pending & ICSK_ACK_TIMER))
4ed800d02cfb63 Gerrit Renker 2006-11-13  187  		goto out;
4ed800d02cfb63 Gerrit Renker 2006-11-13  188  	if (time_after(icsk->icsk_ack.timeout, jiffies)) {
4ed800d02cfb63 Gerrit Renker 2006-11-13  189  		sk_reset_timer(sk, &icsk->icsk_delack_timer,
4ed800d02cfb63 Gerrit Renker 2006-11-13  190  			       icsk->icsk_ack.timeout);
4ed800d02cfb63 Gerrit Renker 2006-11-13  191  		goto out;
4ed800d02cfb63 Gerrit Renker 2006-11-13  192  	}
4ed800d02cfb63 Gerrit Renker 2006-11-13  193  
4ed800d02cfb63 Gerrit Renker 2006-11-13  194  	icsk->icsk_ack.pending &= ~ICSK_ACK_TIMER;
4ed800d02cfb63 Gerrit Renker 2006-11-13  195  
4ed800d02cfb63 Gerrit Renker 2006-11-13  196  	if (inet_csk_ack_scheduled(sk)) {
31954cd8bb6670 Wei Wang      2019-01-25  197  		if (!inet_csk_in_pingpong_mode(sk)) {
4ed800d02cfb63 Gerrit Renker 2006-11-13  198  			/* Delayed ACK missed: inflate ATO. */
4ed800d02cfb63 Gerrit Renker 2006-11-13 @199  			icsk->icsk_ack.ato = min(icsk->icsk_ack.ato << 1,
4ed800d02cfb63 Gerrit Renker 2006-11-13  200  						 icsk->icsk_rto);
4ed800d02cfb63 Gerrit Renker 2006-11-13  201  		} else {
4ed800d02cfb63 Gerrit Renker 2006-11-13  202  			/* Delayed ACK missed: leave pingpong mode and
4ed800d02cfb63 Gerrit Renker 2006-11-13  203  			 * deflate ATO.
4ed800d02cfb63 Gerrit Renker 2006-11-13  204  			 */
31954cd8bb6670 Wei Wang      2019-01-25  205  			inet_csk_exit_pingpong_mode(sk);
4ed800d02cfb63 Gerrit Renker 2006-11-13  206  			icsk->icsk_ack.ato = TCP_ATO_MIN;
4ed800d02cfb63 Gerrit Renker 2006-11-13  207  		}
4ed800d02cfb63 Gerrit Renker 2006-11-13  208  		dccp_send_ack(sk);
02a1d6e7a6bb02 Eric Dumazet  2016-04-27  209  		__NET_INC_STATS(sock_net(sk), LINUX_MIB_DELAYEDACKS);
4ed800d02cfb63 Gerrit Renker 2006-11-13  210  	}
4ed800d02cfb63 Gerrit Renker 2006-11-13  211  out:
4ed800d02cfb63 Gerrit Renker 2006-11-13  212  	bh_unlock_sock(sk);
4ed800d02cfb63 Gerrit Renker 2006-11-13  213  	sock_put(sk);
4ed800d02cfb63 Gerrit Renker 2006-11-13  214  }
4ed800d02cfb63 Gerrit Renker 2006-11-13  215
diff mbox series

Patch

diff --git a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h
index 5d2fcc137b88..d6d9d1c1985a 100644
--- a/include/net/inet_connection_sock.h
+++ b/include/net/inet_connection_sock.h
@@ -114,7 +114,10 @@  struct inet_connection_sock {
 		__u8		  quick;	 /* Scheduled number of quick acks	   */
 		__u8		  pingpong;	 /* The session is interactive		   */
 		__u8		  retry;	 /* Number of attempts			   */
-		__u32		  ato;		 /* Predicted tick of soft clock	   */
+		#define ATO_BITS 8
+		__u32		  ato:ATO_BITS,	 /* Predicted tick of soft clock	   */
+				  lrcv_flowlabel:20, /* last received ipv6 flowlabel	   */
+				  unused:4;
 		unsigned long	  timeout;	 /* Currently scheduled timeout		   */
 		__u32		  lrcvtime;	 /* timestamp of last received data packet */
 		__u16		  last_seg_size; /* Size of last incoming segment	   */
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 91688d0dadcd..8a3720c7d082 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -131,6 +131,8 @@  void tcp_time_wait(struct sock *sk, int state, int timeo);
 #define TCP_FIN_TIMEOUT_MAX (120 * HZ) /* max TCP_LINGER2 value (two minutes) */
 
 #define TCP_DELACK_MAX	((unsigned)(HZ/5))	/* maximal time to delay before sending an ACK */
+static_assert(1<<ATO_BITS > TCP_DELACK_MAX);
+
 #if HZ >= 100
 #define TCP_DELACK_MIN	((unsigned)(HZ/25))	/* minimal time to delay before sending an ACK */
 #define TCP_ATO_MIN	((unsigned)(HZ/25))
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 584825ddd0a0..abe7494361c0 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -765,6 +765,16 @@  void tcp_rcv_space_adjust(struct sock *sk)
 	tp->rcvq_space.time = tp->tcp_mstamp;
 }
 
+static void tcp_save_lrcv_flowlabel(struct sock *sk, const struct sk_buff *skb)
+{
+#if IS_ENABLED(CONFIG_IPV6)
+	struct inet_connection_sock *icsk = inet_csk(sk);
+
+	if (skb->protocol == htons(ETH_P_IPV6))
+		icsk->icsk_ack.lrcv_flowlabel = ntohl(ip6_flowlabel(ipv6_hdr(skb)));
+#endif
+}
+
 /* There is something which you must keep in mind when you analyze the
  * behavior of the tp->ato delayed ack timeout interval.  When a
  * connection starts up, we want to ack as quickly as possible.  The
@@ -813,6 +823,7 @@  static void tcp_event_data_recv(struct sock *sk, struct sk_buff *skb)
 		}
 	}
 	icsk->icsk_ack.lrcvtime = now;
+	tcp_save_lrcv_flowlabel(sk, skb);
 
 	tcp_ecn_check_ce(sk, skb);
 
@@ -4506,6 +4517,9 @@  static void tcp_rcv_spurious_retrans(struct sock *sk, const struct sk_buff *skb)
 	if (TCP_SKB_CB(skb)->seq == tcp_sk(sk)->duplicate_sack[0].start_seq &&
 	    sk_rethink_txhash(sk))
 		NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPDUPLICATEDATAREHASH);
+
+	/* Save last flowlabel after a spurious retrans. */
+	tcp_save_lrcv_flowlabel(sk, skb);
 }
 
 static void tcp_send_dupack(struct sock *sk, const struct sk_buff *skb)
@@ -4822,6 +4836,7 @@  static void tcp_data_queue_ofo(struct sock *sk, struct sk_buff *skb)
 	u32 seq, end_seq;
 	bool fragstolen;
 
+	tcp_save_lrcv_flowlabel(sk, skb);
 	tcp_ecn_check_ce(sk, skb);
 
 	if (unlikely(tcp_try_rmem_schedule(sk, skb, skb->truesize))) {
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index 3f61c6a70a1f..0862b73dd3b5 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -322,7 +322,7 @@  void tcp_delack_timer_handler(struct sock *sk)
 	if (inet_csk_ack_scheduled(sk)) {
 		if (!inet_csk_in_pingpong_mode(sk)) {
 			/* Delayed ACK missed: inflate ATO. */
-			icsk->icsk_ack.ato = min(icsk->icsk_ack.ato << 1, icsk->icsk_rto);
+			icsk->icsk_ack.ato = min_t(u32, icsk->icsk_ack.ato << 1, icsk->icsk_rto);
 		} else {
 			/* Delayed ACK missed: leave pingpong mode and
 			 * deflate ATO.