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sockets: use positive flag for file descriptor socket reference

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Rename SS_NOFDREF to SS_FDREF and flip all bitwise operations.
Mark sockets created by socreate() with SS_FDREF.

This change is mostly illustrative. With it we see that SS_FDREF
is a debugging flag, since:
* socreate() takes a reference with soref().
* on accept path solisten_dequeue() takes a reference
  with soref() and then soaccept() sets SS_FDREF.
* soclose() checks SS_FDREF, removes it and does sorele().

Reviewed by:		tuexen
Differential revision:	https://reviews.freebsd.org/D35678
This commit is contained in:
Gleb Smirnoff 2022-07-04 12:40:51 -07:00
parent 74703901d8
commit bc7605647c
3 changed files with 20 additions and 17 deletions
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4
sys/kern/uipc_debug.c
View File

@ -158,8 +158,8 @@ db_print_sostate(short so_state)
int comma;
comma = 0;
if (so_state & SS_NOFDREF) {
db_printf("%sSS_NOFDREF", comma ? ", " : "");
if (so_state & SS_FDREF) {
db_printf("%sSS_FDREF", comma ? ", " : "");
comma = 1;
}
if (so_state & SS_ISCONNECTED) {

31
sys/kern/uipc_socket.c
View File

@ -498,8 +498,8 @@ sodealloc(struct socket *so)
}
/*
* socreate returns a socket with a ref count of 1. The socket should be
* closed with soclose().
* socreate returns a socket with a ref count of 1 and a file descriptor
* reference. The socket should be closed with soclose().
*/
int
socreate(int dom, struct socket **aso, int type, int proto,
@ -540,6 +540,7 @@ socreate(int dom, struct socket **aso, int type, int proto,
return (ENOBUFS);
so->so_type = type;
so->so_state = SS_FDREF;
so->so_cred = crhold(cred);
if ((prp->pr_domain->dom_family == PF_INET) ||
(prp->pr_domain->dom_family == PF_INET6) ||
@ -740,7 +741,7 @@ sonewconn(struct socket *head, int connstatus)
so->so_type = head->so_type;
so->so_options = head->so_options & ~SO_ACCEPTCONN;
so->so_linger = head->so_linger;
so->so_state = head->so_state | SS_NOFDREF;
so->so_state = head->so_state & ~SS_FDREF;
so->so_fibnum = head->so_fibnum;
so->so_proto = head->so_proto;
so->so_cred = crhold(head->so_cred);
@ -1126,7 +1127,7 @@ solisten_dequeue(struct socket *head, struct socket **ret, int flags)
* - There are no outstanding file descriptor references or related consumers
* (so_count == 0).
*
* - The socket has been closed by user space, if ever open (SS_NOFDREF).
* - The socket has been closed by user space, if ever open (no SS_FDREF).
*
* - The protocol does not have an outstanding strong reference on the socket
* (SS_PROTOREF).
@ -1143,7 +1144,7 @@ sofree(struct socket *so)
SOCK_LOCK_ASSERT(so);
if ((so->so_state & (SS_NOFDREF | SS_PROTOREF)) != SS_NOFDREF ||
if ((so->so_state & (SS_FDREF | SS_PROTOREF)) != 0 ||
refcount_load(&so->so_count) != 0 || so->so_qstate == SQ_COMP) {
SOCK_UNLOCK(so);
return;
@ -1159,7 +1160,7 @@ sofree(struct socket *so)
* To solve race between close of a listening socket and
* a socket on its incomplete queue, we need to lock both.
* The order is first listening socket, then regular.
* Since we don't have SS_NOFDREF neither SS_PROTOREF, this
* Since we don't have SS_FDREF neither SS_PROTOREF, this
* function and the listening socket are the only pointers
* to so. To preserve so and sol, we reference both and then
* relock.
@ -1254,7 +1255,8 @@ soclose(struct socket *so)
int error = 0;
bool listening, last __diagused;
KASSERT(!(so->so_state & SS_NOFDREF), ("soclose: SS_NOFDREF on enter"));
KASSERT(so->so_state & SS_FDREF,
("%s: %p no SS_FDREF on enter", __func__, so));
CURVNET_SET(so->so_vnet);
funsetown(&so->so_sigio);
@ -1306,8 +1308,9 @@ soclose(struct socket *so)
__func__, so));
}
}
KASSERT((so->so_state & SS_NOFDREF) == 0, ("soclose: NOFDREF"));
so->so_state |= SS_NOFDREF;
KASSERT(so->so_state & SS_FDREF,
("%s: %p no SS_FDREF upon lock", __func__, so));
so->so_state &= ~SS_FDREF;
sorele_locked(so);
if (listening) {
struct socket *sp, *tsp;
@ -1352,9 +1355,8 @@ soabort(struct socket *so)
* current thread is responsible for arranging for no references, but
* is as close as we can get for now.
*/
KASSERT(so->so_count == 0, ("soabort: so_count"));
KASSERT((so->so_state & SS_PROTOREF) == 0, ("soabort: SS_PROTOREF"));
KASSERT(so->so_state & SS_NOFDREF, ("soabort: !SS_NOFDREF"));
KASSERT((so->so_state & (SS_FDREF | SS_PROTOREF)) == 0 &&
so->so_count == 0, ("%s: so %p has references", __func__, so));
VNET_SO_ASSERT(so);
if (so->so_proto->pr_usrreqs->pru_abort != NULL)
@ -1369,8 +1371,9 @@ soaccept(struct socket *so, struct sockaddr **nam)
int error;
SOCK_LOCK(so);
KASSERT((so->so_state & SS_NOFDREF) != 0, ("soaccept: !NOFDREF"));
so->so_state &= ~SS_NOFDREF;
KASSERT((so->so_state & SS_FDREF) == 0,
("%s: %p has SS_FDREF", __func__, so));
so->so_state |= SS_FDREF;
SOCK_UNLOCK(so);
CURVNET_SET(so->so_vnet);

2
sys/sys/socketvar.h
View File

@ -210,7 +210,7 @@ struct socket {
* Many fields will be read without locks to improve performance and avoid
* lock order issues. However, this approach must be used with caution.
*/
#define SS_NOFDREF 0x0001 /* no file table ref any more */
#define SS_FDREF 0x0001 /* strong file descriptor reference */
#define SS_ISCONNECTED 0x0002 /* socket connected to a peer */
#define SS_ISCONNECTING 0x0004 /* in process of connecting to peer */
#define SS_ISDISCONNECTING 0x0008 /* in process of disconnecting */