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Code Issues Releases Activity

Remove two simultaneous acquisitions of multiple unpcb locks from

Browse Source 
uipc_send in cases where only a global read lock is held by breaking
them out and avoiding the unpcb lock acquire in the common case.  This
avoids deadlocks which manifested with X11, and should also marginally
further improve performance.

Reported by:	sepotvin, brooks
This commit is contained in:
Robert Watson 2007-03-01 09:00:42 +00:00
parent 6fccc5ecd4
commit ede6e136f8
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=167133
1 changed files with 19 additions and 22 deletions
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41
sys/kern/uipc_usrreq.c
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@ -774,21 +774,18 @@ uipc_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *nam,
unp2 = unp->unp_conn;
if (nam != NULL) {
UNP_GLOBAL_WLOCK_ASSERT();
if (unp2 != NULL) {
error = EISCONN;
UNP_PCB_LOCK(unp);
break;
}
error = unp_connect(so, nam, td);
UNP_PCB_LOCK(unp);
if (error)
break;
unp2 = unp->unp_conn;
} else {
UNP_PCB_LOCK(unp);
if (unp2 == NULL) {
error = ENOTCONN;
UNP_PCB_LOCK(unp);
break;
}
}
@ -799,19 +796,19 @@ uipc_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *nam,
* return the slightly counter-intuitive but otherwise
* correct error that the socket is not connected.
*/
UNP_PCB_LOCK_ASSERT(unp);
if (unp2 == NULL) {
error = ENOTCONN;
break;
}
UNP_PCB_LOCK(unp2);
so2 = unp2->unp_socket;
/* Lockless read. */
if (unp2->unp_flags & UNP_WANTCRED)
control = unp_addsockcred(td, control);
UNP_PCB_LOCK(unp);
if (unp->unp_addr != NULL)
from = (struct sockaddr *)unp->unp_addr;
else
from = &sun_noname;
if (unp2->unp_flags & UNP_WANTCRED)
control = unp_addsockcred(td, control);
so2 = unp2->unp_socket;
SOCKBUF_LOCK(&so2->so_rcv);
if (sbappendaddr_locked(&so2->so_rcv, from, m, control)) {
sorwakeup_locked(so2);
@ -821,9 +818,13 @@ uipc_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *nam,
SOCKBUF_UNLOCK(&so2->so_rcv);
error = ENOBUFS;
}
if (nam != NULL)
if (nam != NULL) {
UNP_GLOBAL_WLOCK_ASSERT();
UNP_PCB_LOCK(unp2);
unp_disconnect(unp, unp2);
UNP_PCB_UNLOCK(unp2);
UNP_PCB_UNLOCK(unp2);
}
UNP_PCB_UNLOCK(unp);
break;
}
@ -836,18 +837,15 @@ uipc_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *nam,
*/
if ((so->so_state & SS_ISCONNECTED) == 0) {
if (nam != NULL) {
UNP_GLOBAL_WLOCK_ASSERT();
error = unp_connect(so, nam, td);
UNP_PCB_LOCK(unp);
if (error)
break; /* XXX */
} else {
error = ENOTCONN;
UNP_PCB_LOCK(unp);
break;
}
} else
UNP_PCB_LOCK(unp);
UNP_PCB_LOCK_ASSERT(unp);
}
/* Lockless read. */
if (so->so_snd.sb_state & SBS_CANTSENDMORE) {
@ -874,13 +872,12 @@ uipc_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *nam,
error = ENOTCONN;
break;
}
UNP_PCB_LOCK(unp2);
so2 = unp2->unp_socket;
UNP_PCB_LOCK(unp2);
SOCKBUF_LOCK(&so2->so_rcv);
if (unp2->unp_flags & UNP_WANTCRED) {
/*
* Credentials are passed only once on
* SOCK_STREAM.
* Credentials are passed only once on SOCK_STREAM.
*/
unp2->unp_flags &= ~UNP_WANTCRED;
control = unp_addsockcred(td, control);
@ -915,14 +912,14 @@ uipc_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *nam,
}
/*
* SEND_EOF is equivalent to a SEND followed by
* a SHUTDOWN.
* SEND_EOF is equivalent to a SEND followed by a SHUTDOWN.
*/
if (flags & PRUS_EOF) {
UNP_PCB_LOCK(unp);
socantsendmore(so);
unp_shutdown(unp);
UNP_PCB_UNLOCK(unp);
}
UNP_PCB_UNLOCK(unp);
if ((nam != NULL) || (flags & PRUS_EOF))
UNP_GLOBAL_WUNLOCK();