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net: Introduce recvmmsg socket syscall

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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>
This commit is contained in:
Arnaldo Carvalho de Melo
2009-10-12 23:40:10 -07:00
committed by David S. Miller
parent c05e85a06e
commit a2e2725541
25 changed files with 261 additions and 50 deletions
Download Patch File Download Diff File Expand all files Collapse all files

33
net/compat.c
View File

@@ -727,10 +727,10 @@ EXPORT_SYMBOL(compat_mc_getsockopt);
/* Argument list sizes for compat_sys_socketcall */
#define AL(x) ((x) * sizeof(u32))
static unsigned char nas[19]={AL(0),AL(3),AL(3),AL(3),AL(2),AL(3),
static unsigned char nas[20]={AL(0),AL(3),AL(3),AL(3),AL(2),AL(3),
AL(3),AL(3),AL(4),AL(4),AL(4),AL(6),
AL(6),AL(2),AL(5),AL(5),AL(3),AL(3),
AL(4)};
AL(4),AL(5)};
#undef AL
asmlinkage long compat_sys_sendmsg(int fd, struct compat_msghdr __user *msg, unsigned flags)
@@ -755,13 +755,36 @@ asmlinkage long compat_sys_recvfrom(int fd, void __user *buf, size_t len,
return sys_recvfrom(fd, buf, len, flags | MSG_CMSG_COMPAT, addr, addrlen);
}
asmlinkage long compat_sys_recvmmsg(int fd, struct compat_mmsghdr __user *mmsg,
unsigned vlen, unsigned int flags,
struct timespec __user *timeout)
{
int datagrams;
struct timespec ktspec;
struct compat_timespec __user *utspec =
(struct compat_timespec __user *)timeout;
if (get_user(ktspec.tv_sec, &utspec->tv_sec) ||
get_user(ktspec.tv_nsec, &utspec->tv_nsec))
return -EFAULT;
datagrams = __sys_recvmmsg(fd, (struct mmsghdr __user *)mmsg, vlen,
flags | MSG_CMSG_COMPAT, &ktspec);
if (datagrams > 0 &&
(put_user(ktspec.tv_sec, &utspec->tv_sec) ||
put_user(ktspec.tv_nsec, &utspec->tv_nsec)))
datagrams = -EFAULT;
return datagrams;
}
asmlinkage long compat_sys_socketcall(int call, u32 __user *args)
{
int ret;
u32 a[6];
u32 a0, a1;
if (call < SYS_SOCKET || call > SYS_ACCEPT4)
if (call < SYS_SOCKET || call > SYS_RECVMMSG)
return -EINVAL;
if (copy_from_user(a, args, nas[call]))
return -EFAULT;
@@ -823,6 +846,10 @@ asmlinkage long compat_sys_socketcall(int call, u32 __user *args)
case SYS_RECVMSG:
ret = compat_sys_recvmsg(a0, compat_ptr(a1), a[2]);
break;
case SYS_RECVMMSG:
ret = compat_sys_recvmmsg(a0, compat_ptr(a1), a[2], a[3],
compat_ptr(a[4]));
break;
case SYS_ACCEPT4:
ret = sys_accept4(a0, compat_ptr(a1), compat_ptr(a[2]), a[3]);
break;