net: Facility to report route quality of connected sockets

This patch add the SO_CNX_ADVICE socket option (setsockopt only). The
purpose is to allow an application to give feedback to the kernel about
the quality of the network path for a connected socket. The value
argument indicates the type of quality report. For this initial patch
the only supported advice is a value of 1 which indicates "bad path,
please reroute"-- the action taken by the kernel is to call
dst_negative_advice which will attempt to choose a different ECMP route,
reset the TX hash for flow label and UDP source port in encapsulation,
etc.

This facility should be useful for connected UDP sockets where only the
application can provide any feedback about path quality. It could also
be useful for TCP applications that have additional knowledge about the
path outside of the normal TCP control loop.

Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

14 files changed, 30 insertions, 0 deletions

diff --git a/arch/alpha/include/uapi/asm/socket.h b/arch/alpha/include/uapi/asm/socket.h
index c5fb9e6bc3a5..9e46d6e656d9 100644
--- a/arch/alpha/include/uapi/asm/socket.h
+++ b/arch/alpha/include/uapi/asm/socket.h
@@ -95,4 +95,6 @@
 #define SO_ATTACH_REUSEPORT_CBPF	51
 #define SO_ATTACH_REUSEPORT_EBPF	52
 
+#define SO_CNX_ADVICE		53
+
 #endif /* _UAPI_ASM_SOCKET_H */
diff --git a/arch/avr32/include/uapi/asm/socket.h b/arch/avr32/include/uapi/asm/socket.h
index 9de0796240a0..1fd147f09a38 100644
--- a/arch/avr32/include/uapi/asm/socket.h
+++ b/arch/avr32/include/uapi/asm/socket.h
@@ -88,4 +88,6 @@
 #define SO_ATTACH_REUSEPORT_CBPF	51
 #define SO_ATTACH_REUSEPORT_EBPF	52
 
+#define SO_CNX_ADVICE		53
+
 #endif /* _UAPI__ASM_AVR32_SOCKET_H */
diff --git a/arch/frv/include/uapi/asm/socket.h b/arch/frv/include/uapi/asm/socket.h
index f02e4849ae83..afbc98f02d27 100644
--- a/arch/frv/include/uapi/asm/socket.h
+++ b/arch/frv/include/uapi/asm/socket.h
@@ -88,5 +88,7 @@
 #define SO_ATTACH_REUSEPORT_CBPF	51
 #define SO_ATTACH_REUSEPORT_EBPF	52
 
+#define SO_CNX_ADVICE		53
+
 #endif /* _ASM_SOCKET_H */
 
diff --git a/arch/ia64/include/uapi/asm/socket.h b/arch/ia64/include/uapi/asm/socket.h
index bce29166de1b..0018fad9039f 100644
--- a/arch/ia64/include/uapi/asm/socket.h
+++ b/arch/ia64/include/uapi/asm/socket.h
@@ -97,4 +97,6 @@
 #define SO_ATTACH_REUSEPORT_CBPF	51
 #define SO_ATTACH_REUSEPORT_EBPF	52
 
+#define SO_CNX_ADVICE		53
+
 #endif /* _ASM_IA64_SOCKET_H */
diff --git a/arch/m32r/include/uapi/asm/socket.h b/arch/m32r/include/uapi/asm/socket.h
index 14aa4a6bccf1..5fe42fc7b6c5 100644
--- a/arch/m32r/include/uapi/asm/socket.h
+++ b/arch/m32r/include/uapi/asm/socket.h
@@ -88,4 +88,6 @@
 #define SO_ATTACH_REUSEPORT_CBPF	51
 #define SO_ATTACH_REUSEPORT_EBPF	52
 
+#define SO_CNX_ADVICE		53
+
 #endif /* _ASM_M32R_SOCKET_H */
diff --git a/arch/mips/include/uapi/asm/socket.h b/arch/mips/include/uapi/asm/socket.h
index 5910fe294e93..2027240aafbb 100644
--- a/arch/mips/include/uapi/asm/socket.h
+++ b/arch/mips/include/uapi/asm/socket.h
@@ -106,4 +106,6 @@
 #define SO_ATTACH_REUSEPORT_CBPF	51
 #define SO_ATTACH_REUSEPORT_EBPF	52
 
+#define SO_CNX_ADVICE		53
+
 #endif /* _UAPI_ASM_SOCKET_H */
diff --git a/arch/mn10300/include/uapi/asm/socket.h b/arch/mn10300/include/uapi/asm/socket.h
index 58b1aa01ab9f..5129f23a9ee1 100644
--- a/arch/mn10300/include/uapi/asm/socket.h
+++ b/arch/mn10300/include/uapi/asm/socket.h
@@ -88,4 +88,6 @@
 #define SO_ATTACH_REUSEPORT_CBPF	51
 #define SO_ATTACH_REUSEPORT_EBPF	52
 
+#define SO_CNX_ADVICE		53
+
 #endif /* _ASM_SOCKET_H */
diff --git a/arch/parisc/include/uapi/asm/socket.h b/arch/parisc/include/uapi/asm/socket.h
index f9cf1223422c..9c935d717df9 100644
--- a/arch/parisc/include/uapi/asm/socket.h
+++ b/arch/parisc/include/uapi/asm/socket.h
@@ -87,4 +87,6 @@
 #define SO_ATTACH_REUSEPORT_CBPF	0x402C
 #define SO_ATTACH_REUSEPORT_EBPF	0x402D
 
+#define SO_CNX_ADVICE		0x402E
+
 #endif /* _UAPI_ASM_SOCKET_H */
diff --git a/arch/powerpc/include/uapi/asm/socket.h b/arch/powerpc/include/uapi/asm/socket.h
index dd54f28ecdec..1672e3398270 100644
--- a/arch/powerpc/include/uapi/asm/socket.h
+++ b/arch/powerpc/include/uapi/asm/socket.h
@@ -95,4 +95,6 @@
 #define SO_ATTACH_REUSEPORT_CBPF	51
 #define SO_ATTACH_REUSEPORT_EBPF	52
 
+#define SO_CNX_ADVICE		53
+
 #endif	/* _ASM_POWERPC_SOCKET_H */
diff --git a/arch/s390/include/uapi/asm/socket.h b/arch/s390/include/uapi/asm/socket.h
index d02e89d14fef..41b51c2f4f1b 100644
--- a/arch/s390/include/uapi/asm/socket.h
+++ b/arch/s390/include/uapi/asm/socket.h
@@ -94,4 +94,6 @@
 #define SO_ATTACH_REUSEPORT_CBPF	51
 #define SO_ATTACH_REUSEPORT_EBPF	52
 
+#define SO_CNX_ADVICE		53
+
 #endif /* _ASM_SOCKET_H */
diff --git a/arch/sparc/include/uapi/asm/socket.h b/arch/sparc/include/uapi/asm/socket.h
index d270ee91968e..31aede3af088 100644
--- a/arch/sparc/include/uapi/asm/socket.h
+++ b/arch/sparc/include/uapi/asm/socket.h
@@ -84,6 +84,8 @@
 #define SO_ATTACH_REUSEPORT_CBPF	0x0035
 #define SO_ATTACH_REUSEPORT_EBPF	0x0036
 
+#define SO_CNX_ADVICE		0x0037
+
 /* Security levels - as per NRL IPv6 - don't actually do anything */
 #define SO_SECURITY_AUTHENTICATION		0x5001
 #define SO_SECURITY_ENCRYPTION_TRANSPORT	0x5002
diff --git a/arch/xtensa/include/uapi/asm/socket.h b/arch/xtensa/include/uapi/asm/socket.h
index fd3b96d1153f..81435d995e11 100644
--- a/arch/xtensa/include/uapi/asm/socket.h
+++ b/arch/xtensa/include/uapi/asm/socket.h
@@ -99,4 +99,6 @@
 #define SO_ATTACH_REUSEPORT_CBPF	51
 #define SO_ATTACH_REUSEPORT_EBPF	52
 
+#define SO_CNX_ADVICE		53
+
 #endif	/* _XTENSA_SOCKET_H */
diff --git a/include/uapi/asm-generic/socket.h b/include/uapi/asm-generic/socket.h
index fb8a41668382..67d632f1743d 100644
--- a/include/uapi/asm-generic/socket.h
+++ b/include/uapi/asm-generic/socket.h
@@ -90,4 +90,6 @@
 #define SO_ATTACH_REUSEPORT_CBPF	51
 #define SO_ATTACH_REUSEPORT_EBPF	52
 
+#define SO_CNX_ADVICE		53
+
 #endif /* __ASM_GENERIC_SOCKET_H */
diff --git a/net/core/sock.c b/net/core/sock.c
index 46dc8ad7d050..4493ff820c2c 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -987,6 +987,10 @@ set_rcvbuf:
 		sk->sk_incoming_cpu = val;
 		break;
 
+	case SO_CNX_ADVICE:
+		if (val == 1)
+			dst_negative_advice(sk);
+		break;
 	default:
 		ret = -ENOPROTOOPT;
 		break;