net: Introduce recvmmsg socket syscall

Meaning receive multiple messages, reducing the number of syscalls and
net stack entry/exit operations.

Next patches will introduce mechanisms where protocols that want to
optimize this operation will provide an unlocked_recvmsg operation.

This takes into account comments made by:

. Paul Moore: sock_recvmsg is called only for the first datagram,
  sock_recvmsg_nosec is used for the rest.

. Caitlin Bestler: recvmmsg now has a struct timespec timeout, that
  works in the same fashion as the ppoll one.

  If the underlying protocol returns a datagram with MSG_OOB set, this
  will make recvmmsg return right away with as many datagrams (+ the OOB
  one) it has received so far.

. Rémi Denis-Courmont & Steven Whitehouse: If we receive N < vlen
  datagrams and then recvmsg returns an error, recvmmsg will return
  the successfully received datagrams, store the error and return it
  in the next call.

This paves the way for a subsequent optimization, sk_prot->unlocked_recvmsg,
where we will be able to acquire the lock only at batch start and end, not at
every underlying recvmsg call.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/alpha/kernel/systbls.S

@@ -497,6 +497,7 @@ sys_call_table:
 	.quad sys_signalfd
 	.quad sys_ni_syscall
 	.quad sys_eventfd
+	.quad sys_recvmmsg
 
 	.size sys_call_table, . - sys_call_table
 	.type sys_call_table, @object

arch/arm/kernel/calls.S

@@ -374,6 +374,7 @@
 		CALL(sys_pwritev)
 		CALL(sys_rt_tgsigqueueinfo)
 		CALL(sys_perf_event_open)
+/* 365 */	CALL(sys_recvmmsg)
 #ifndef syscalls_counted
 .equ syscalls_padding, ((NR_syscalls + 3) & ~3) - NR_syscalls
 #define syscalls_counted

arch/avr32/kernel/syscall_table.S

@@ -295,4 +295,5 @@ sys_call_table:
 	.long	sys_signalfd
 	.long	sys_ni_syscall		/* 280, was sys_timerfd */
 	.long	sys_eventfd
+	.long	sys_recvmmsg
 	.long	sys_ni_syscall		/* r8 is saturated at nr_syscalls */

arch/blackfin/mach-common/entry.S

@@ -1621,6 +1621,7 @@ ENTRY(_sys_call_table)
 	.long _sys_pwritev
 	.long _sys_rt_tgsigqueueinfo
 	.long _sys_perf_event_open
+	.long _sys_recvmmsg		/* 370 */
 
 	.rept NR_syscalls-(.-_sys_call_table)/4
 	.long _sys_ni_syscall

arch/ia64/kernel/entry.S

@@ -1806,6 +1806,7 @@ sys_call_table:
 	data8 sys_preadv
 	data8 sys_pwritev			// 1320
 	data8 sys_rt_tgsigqueueinfo
+	data8 sys_recvmmsg
 
 	.org sys_call_table + 8*NR_syscalls	// guard against failures to increase NR_syscalls
 #endif /* __IA64_ASM_PARAVIRTUALIZED_NATIVE */

arch/microblaze/kernel/syscall_table.S

@@ -371,3 +371,4 @@ ENTRY(sys_call_table)
 	.long sys_ni_syscall
 	.long sys_rt_tgsigqueueinfo	/* 365 */
 	.long sys_perf_event_open
+	.long sys_recvmmsg

arch/mips/kernel/scall32-o32.S

@@ -583,6 +583,7 @@ einval:	li	v0, -ENOSYS
 	sys	sys_rt_tgsigqueueinfo	4
 	sys	sys_perf_event_open	5
 	sys	sys_accept4		4
+	sys     sys_recvmmsg            5
 	.endm
 
 	/* We pre-compute the number of _instruction_ bytes needed to

arch/mips/kernel/scall64-64.S

@@ -420,4 +420,5 @@ sys_call_table:
 	PTR	sys_rt_tgsigqueueinfo
 	PTR	sys_perf_event_open
 	PTR	sys_accept4
+	PTR     sys_recvmmsg
 	.size	sys_call_table,.-sys_call_table

arch/mips/kernel/scall64-n32.S

@@ -418,4 +418,5 @@ EXPORT(sysn32_call_table)
 	PTR	compat_sys_rt_tgsigqueueinfo	/* 5295 */
 	PTR	sys_perf_event_open
 	PTR	sys_accept4
+	PTR     compat_sys_recvmmsg
 	.size	sysn32_call_table,.-sysn32_call_table

arch/mips/kernel/scall64-o32.S

@@ -538,4 +538,5 @@ sys_call_table:
 	PTR	compat_sys_rt_tgsigqueueinfo
 	PTR	sys_perf_event_open
 	PTR	sys_accept4
+	PTR     compat_sys_recvmmsg
 	.size	sys_call_table,.-sys_call_table

arch/sh/kernel/syscalls_64.S

@@ -391,3 +391,4 @@ sys_call_table:
 	.long sys_pwritev
 	.long sys_rt_tgsigqueueinfo
 	.long sys_perf_event_open
+	.long sys_recvmmsg		/* 365 */

arch/sparc/kernel/systbls_32.S

@@ -82,5 +82,5 @@ sys_call_table:
 /*310*/	.long sys_utimensat, sys_signalfd, sys_timerfd_create, sys_eventfd, sys_fallocate
 /*315*/	.long sys_timerfd_settime, sys_timerfd_gettime, sys_signalfd4, sys_eventfd2, sys_epoll_create1
 /*320*/	.long sys_dup3, sys_pipe2, sys_inotify_init1, sys_accept4, sys_preadv
-/*325*/	.long sys_pwritev, sys_rt_tgsigqueueinfo, sys_perf_event_open
+/*325*/	.long sys_pwritev, sys_rt_tgsigqueueinfo, sys_perf_event_open, sys_recvmmsg
 

arch/sparc/kernel/systbls_64.S

@@ -83,7 +83,7 @@ sys_call_table32:
 /*310*/	.word compat_sys_utimensat, compat_sys_signalfd, sys_timerfd_create, sys_eventfd, compat_sys_fallocate
 	.word compat_sys_timerfd_settime, compat_sys_timerfd_gettime, compat_sys_signalfd4, sys_eventfd2, sys_epoll_create1
 /*320*/	.word sys_dup3, sys_pipe2, sys_inotify_init1, sys_accept4, compat_sys_preadv
-	.word compat_sys_pwritev, compat_sys_rt_tgsigqueueinfo, sys_perf_event_open
+	.word compat_sys_pwritev, compat_sys_rt_tgsigqueueinfo, sys_perf_event_open, compat_sys_recvmmsg
 
 #endif /* CONFIG_COMPAT */
 
@@ -158,4 +158,4 @@ sys_call_table:
 /*310*/	.word sys_utimensat, sys_signalfd, sys_timerfd_create, sys_eventfd, sys_fallocate
 	.word sys_timerfd_settime, sys_timerfd_gettime, sys_signalfd4, sys_eventfd2, sys_epoll_create1
 /*320*/	.word sys_dup3, sys_pipe2, sys_inotify_init1, sys_accept4, sys_preadv
-	.word sys_pwritev, sys_rt_tgsigqueueinfo, sys_perf_event_open
+	.word sys_pwritev, sys_rt_tgsigqueueinfo, sys_perf_event_open, sys_recvmmsg

arch/x86/ia32/ia32entry.S

@@ -832,4 +832,5 @@ ia32_sys_call_table:
 	.quad compat_sys_pwritev
 	.quad compat_sys_rt_tgsigqueueinfo	/* 335 */
 	.quad sys_perf_event_open
+	.quad compat_sys_recvmmsg
 ia32_syscall_end:

arch/x86/include/asm/unistd_32.h

@@ -342,10 +342,11 @@
 #define __NR_pwritev		334
 #define __NR_rt_tgsigqueueinfo	335
 #define __NR_perf_event_open	336
+#define __NR_recvmmsg		337
 
 #ifdef __KERNEL__
 
-#define NR_syscalls 337
+#define NR_syscalls 338
 
 #define __ARCH_WANT_IPC_PARSE_VERSION
 #define __ARCH_WANT_OLD_READDIR

arch/x86/include/asm/unistd_64.h

@@ -661,6 +661,8 @@ __SYSCALL(__NR_pwritev, sys_pwritev)
 __SYSCALL(__NR_rt_tgsigqueueinfo, sys_rt_tgsigqueueinfo)
 #define __NR_perf_event_open			298
 __SYSCALL(__NR_perf_event_open, sys_perf_event_open)
+#define __NR_recvmmsg				299
+__SYSCALL(__NR_recvmmsg, sys_recvmmsg)
 
 #ifndef __NO_STUBS
 #define __ARCH_WANT_OLD_READDIR

arch/x86/kernel/syscall_table_32.S

@@ -336,3 +336,4 @@ ENTRY(sys_call_table)
 	.long sys_pwritev
 	.long sys_rt_tgsigqueueinfo	/* 335 */
 	.long sys_perf_event_open
+	.long sys_recvmmsg

arch/xtensa/include/asm/unistd.h

@@ -681,8 +681,10 @@ __SYSCALL(304, sys_signalfd, 3)
 __SYSCALL(305, sys_ni_syscall, 0)
 #define __NR_eventfd				306
 __SYSCALL(306, sys_eventfd, 1)
+#define __NR_recvmmsg				307
+__SYSCALL(307, sys_recvmmsg, 5)
 
-#define __NR_syscall_count			307
+#define __NR_syscall_count			308
 
 /*
  * sysxtensa syscall handler

include/linux/net.h

@@ -41,6 +41,7 @@
 #define SYS_SENDMSG	16		/* sys_sendmsg(2)		*/
 #define SYS_RECVMSG	17		/* sys_recvmsg(2)		*/
 #define SYS_ACCEPT4	18		/* sys_accept4(2)		*/
+#define SYS_RECVMMSG	19		/* sys_recvmmsg(2)		*/
 
 typedef enum {
 	SS_FREE = 0,			/* not allocated		*/

include/linux/socket.h

@@ -65,6 +65,12 @@ struct msghdr {
 	unsigned	msg_flags;
 };
 
+/* For recvmmsg/sendmmsg */
+struct mmsghdr {
+	struct msghdr   msg_hdr;
+	unsigned        msg_len;
+};
+
 /*
  *	POSIX 1003.1g - ancillary data object information
  *	Ancillary data consits of a sequence of pairs of
@@ -312,6 +318,10 @@ extern int move_addr_to_user(struct sockaddr *kaddr, int klen, void __user *uadd
 extern int move_addr_to_kernel(void __user *uaddr, int ulen, struct sockaddr *kaddr);
 extern int put_cmsg(struct msghdr*, int level, int type, int len, void *data);
 
+struct timespec;
+
+extern int __sys_recvmmsg(int fd, struct mmsghdr __user *mmsg, unsigned int vlen,
+			  unsigned int flags, struct timespec *timeout);
 #endif
 #endif /* not kernel and not glibc */
 #endif /* _LINUX_SOCKET_H */