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Merge some additional leaf node socket buffer locking from

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rwatson_netperf:

Introduce conditional locking of the socket buffer in fifofs kqueue
filters; KNOTE() will be called holding the socket buffer locks in
fifofs, but sometimes the kqueue() system call will poll using the
same entry point without holding the socket buffer lock.

Introduce conditional locking of the socket buffer in the socket
kqueue filters; KNOTE() will be called holding the socket buffer
locks in the socket code, but sometimes the kqueue() system call
will poll using the same entry points without holding the socket
buffer lock.

Simplify the logic in sodisconnect() since we no longer need spls.

NOTE: To remove conditional locking in the kqueue filters, it would
make sense to use a separate kqueue API entry into the socket/fifo
code when calling from the kqueue() system call.
This commit is contained in:
Robert Watson 2004-06-18 02:57:55 +00:00
parent da181cc144
commit c012260726
2 changed files with 53 additions and 19 deletions
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33
sys/fs/fifofs/fifo_vnops.c
View File

@ -444,23 +444,33 @@ filt_fifordetach(struct knote *kn)
{
struct socket *so = (struct socket *)kn->kn_hook;
SOCKBUF_LOCK(&so->so_rcv);
SLIST_REMOVE(&so->so_rcv.sb_sel.si_note, kn, knote, kn_selnext);
if (SLIST_EMPTY(&so->so_rcv.sb_sel.si_note))
so->so_rcv.sb_flags &= ~SB_KNOTE;
SOCKBUF_UNLOCK(&so->so_rcv);
}
static int
filt_fiforead(struct knote *kn, long hint)
{
struct socket *so = (struct socket *)kn->kn_hook;
int need_lock, result;
need_lock = !SOCKBUF_OWNED(&so->so_rcv);
if (need_lock)
SOCKBUF_LOCK(&so->so_rcv);
kn->kn_data = so->so_rcv.sb_cc;
if (so->so_rcv.sb_state & SBS_CANTRCVMORE) {
kn->kn_flags |= EV_EOF;
return (1);
result = 1;
} else {
kn->kn_flags &= ~EV_EOF;
result = (kn->kn_data > 0);
}
kn->kn_flags &= ~EV_EOF;
return (kn->kn_data > 0);
if (need_lock)
SOCKBUF_UNLOCK(&so->so_rcv);
return (result);
}
static void
@ -468,23 +478,34 @@ filt_fifowdetach(struct knote *kn)
{
struct socket *so = (struct socket *)kn->kn_hook;
SOCKBUF_LOCK(&so->so_snd);
SLIST_REMOVE(&so->so_snd.sb_sel.si_note, kn, knote, kn_selnext);
if (SLIST_EMPTY(&so->so_snd.sb_sel.si_note))
so->so_snd.sb_flags &= ~SB_KNOTE;
SOCKBUF_UNLOCK(&so->so_snd);
}
static int
filt_fifowrite(struct knote *kn, long hint)
{
struct socket *so = (struct socket *)kn->kn_hook;
int need_lock, result;
need_lock = !SOCKBUF_OWNED(&so->so_snd);
if (need_lock)
SOCKBUF_LOCK(&so->so_snd);
kn->kn_data = sbspace(&so->so_snd);
/* Unlocked read. */
if (so->so_snd.sb_state & SBS_CANTSENDMORE) {
kn->kn_flags |= EV_EOF;
return (1);
result = 1;
} else {
kn->kn_flags &= ~EV_EOF;
result = (kn->kn_data >= so->so_snd.sb_lowat);
}
kn->kn_flags &= ~EV_EOF;
return (kn->kn_data >= so->so_snd.sb_lowat);
if (need_lock)
SOCKBUF_UNLOCK(&so->so_snd);
return (result);
}
/* ARGSUSED */

39
sys/kern/uipc_socket.c
View File

@ -506,20 +506,13 @@ int
sodisconnect(so)
struct socket *so;
{
int s = splnet();
int error;
if ((so->so_state & SS_ISCONNECTED) == 0) {
error = ENOTCONN;
goto bad;
}
if (so->so_state & SS_ISDISCONNECTING) {
error = EALREADY;
goto bad;
}
if ((so->so_state & SS_ISCONNECTED) == 0)
return (ENOTCONN);
if (so->so_state & SS_ISDISCONNECTING)
return (EALREADY);
error = (*so->so_proto->pr_usrreqs->pru_disconnect)(so);
bad:
splx(s);
return (error);
}
@ -1913,8 +1906,16 @@ static int
filt_soread(struct knote *kn, long hint)
{
struct socket *so = kn->kn_fp->f_data;
int result;
int need_lock, result;
/*
* XXXRW: Conditional locking because filt_soread() can be called
* either from KNOTE() in the socket context where the socket buffer
* lock is already held, or from kqueue() itself.
*/
need_lock = !SOCKBUF_OWNED(&so->so_rcv);
if (need_lock)
SOCKBUF_LOCK(&so->so_rcv);
kn->kn_data = so->so_rcv.sb_cc - so->so_rcv.sb_ctl;
if (so->so_rcv.sb_state & SBS_CANTRCVMORE) {
kn->kn_flags |= EV_EOF;
@ -1926,6 +1927,8 @@ filt_soread(struct knote *kn, long hint)
result = (kn->kn_data >= kn->kn_sdata);
else
result = (so->so_rcv.sb_cc >= so->so_rcv.sb_lowat);
if (need_lock)
SOCKBUF_UNLOCK(&so->so_rcv);
return (result);
}
@ -1946,8 +1949,16 @@ static int
filt_sowrite(struct knote *kn, long hint)
{
struct socket *so = kn->kn_fp->f_data;
int result;
int need_lock, result;
/*
* XXXRW: Conditional locking because filt_soread() can be called
* either from KNOTE() in the socket context where the socket buffer
* lock is already held, or from kqueue() itself.
*/
need_lock = !SOCKBUF_OWNED(&so->so_snd);
if (need_lock)
SOCKBUF_LOCK(&so->so_snd);
kn->kn_data = sbspace(&so->so_snd);
if (so->so_snd.sb_state & SBS_CANTSENDMORE) {
kn->kn_flags |= EV_EOF;
@ -1962,6 +1973,8 @@ filt_sowrite(struct knote *kn, long hint)
result = (kn->kn_data >= kn->kn_sdata);
else
result = (kn->kn_data >= so->so_snd.sb_lowat);
if (need_lock)
SOCKBUF_UNLOCK(&so->so_snd);
return (result);
}