linux/include/net/scm.h
Benjamin LaHaise 1d541ddd74 [AF_UNIX]: scm: better initialization
Instead of doing a memset then initialization of the fields of the scm
structure, just initialize all the members explicitly.  Prevent reloading
of current on x86 and x86-64 by storing the value in a local variable for
subsequent dereferences.  This is worth a ~7KB/s increase in af_unix
bandwidth.  Note that we avoid the issues surrounding potentially
uninitialized members of the ucred structure by constructing a struct
ucred instead of assigning the members individually, which forces the
compiler to zero any padding.

[ I modified the patch not to use the aggregate assignment since
  gcc-3.4.x and earlier cannot optimize that properly at all even
  though gcc-4.0.x and later can -DaveM ]

Signed-off-by: Benjamin LaHaise <benjamin.c.lahaise@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-03-20 21:31:51 -08:00

74 lines
1.7 KiB
C

#ifndef __LINUX_NET_SCM_H
#define __LINUX_NET_SCM_H
#include <linux/limits.h>
#include <linux/net.h>
/* Well, we should have at least one descriptor open
* to accept passed FDs 8)
*/
#define SCM_MAX_FD (OPEN_MAX-1)
struct scm_fp_list
{
int count;
struct file *fp[SCM_MAX_FD];
};
struct scm_cookie
{
struct ucred creds; /* Skb credentials */
struct scm_fp_list *fp; /* Passed files */
unsigned long seq; /* Connection seqno */
};
extern void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm);
extern void scm_detach_fds_compat(struct msghdr *msg, struct scm_cookie *scm);
extern int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm);
extern void __scm_destroy(struct scm_cookie *scm);
extern struct scm_fp_list * scm_fp_dup(struct scm_fp_list *fpl);
static __inline__ void scm_destroy(struct scm_cookie *scm)
{
if (scm && scm->fp)
__scm_destroy(scm);
}
static __inline__ int scm_send(struct socket *sock, struct msghdr *msg,
struct scm_cookie *scm)
{
struct task_struct *p = current;
scm->creds.uid = p->uid;
scm->creds.gid = p->gid;
scm->creds.pid = p->tgid;
scm->fp = NULL;
scm->seq = 0;
if (msg->msg_controllen <= 0)
return 0;
return __scm_send(sock, msg, scm);
}
static __inline__ void scm_recv(struct socket *sock, struct msghdr *msg,
struct scm_cookie *scm, int flags)
{
if (!msg->msg_control)
{
if (test_bit(SOCK_PASSCRED, &sock->flags) || scm->fp)
msg->msg_flags |= MSG_CTRUNC;
scm_destroy(scm);
return;
}
if (test_bit(SOCK_PASSCRED, &sock->flags))
put_cmsg(msg, SOL_SOCKET, SCM_CREDENTIALS, sizeof(scm->creds), &scm->creds);
if (!scm->fp)
return;
scm_detach_fds(msg, scm);
}
#endif /* __LINUX_NET_SCM_H */