On 05/12/17(Tue) 14:37, Alexander Bluhm wrote:
> On Mon, Dec 04, 2017 at 03:33:56PM +0100, Martin Pieuchot wrote:
> > Diff below change the usage of `sb_flags' and `sb_flagsintr'.  The
> > former will be protected by the socket lock while the latter will
> > be using atomic operations.
> 
> I like this plan.
> 
> > @@ -381,17 +381,18 @@ sbunlock(struct socket *so, struct sockb
> >  void
> >  sowakeup(struct socket *so, struct sockbuf *sb)
> >  {
> > -   KERNEL_ASSERT_LOCKED();
> >     soassertlocked(so);
> >  
> > -   selwakeup(&sb->sb_sel);
> > -   sb->sb_flagsintr &= ~SB_SEL;
> > -   if (sb->sb_flagsintr & SB_WAIT) {
> > -           sb->sb_flagsintr &= ~SB_WAIT;
> > +   sb->sb_flags &= ~SB_SEL;
> > +   if (sb->sb_flags & SB_WAIT) {
> > +           sb->sb_flags &= ~SB_WAIT;
> >             wakeup(&sb->sb_cc);
> >     }
> > +   KERNEL_LOCK();
> >     if (so->so_state & SS_ASYNC)
> >             csignal(so->so_pgid, SIGIO, so->so_siguid, so->so_sigeuid);
> > +   selwakeup(&sb->sb_sel);
> > +   KERNEL_UNLOCK();
> >  }
> 
> Why do you move the selwakeup() after the csignal() ?

To make it similar to sohasoutofband().

> 
> > @@ -340,6 +342,7 @@ fifo_poll(void *v)
> >                     wso->so_snd.sb_flagsintr |= SB_SEL;
> >             }
> >     }
> > +   sounlock(s);
> >     return (revents);
> >  }
> 
> Here you missed to convert sb_flagsintr |= SB_SEL to sb_flags.
> 
> And in filt_fifowdetach() is still a sb_flags &= ~SB_KNOTE.

Right, updated diff below.

Index: kern/uipc_socket.c
===================================================================
RCS file: /cvs/src/sys/kern/uipc_socket.c,v
retrieving revision 1.209
diff -u -p -r1.209 uipc_socket.c
--- kern/uipc_socket.c  23 Nov 2017 13:45:46 -0000      1.209
+++ kern/uipc_socket.c  4 Dec 2017 14:26:24 -0000
@@ -1054,9 +1054,9 @@ sorflush(struct socket *so)
        aso.so_rcv = *sb;
        memset(sb, 0, sizeof (*sb));
        /* XXX - the memset stomps all over so_rcv */
-       if (aso.so_rcv.sb_flags & SB_KNOTE) {
+       if (aso.so_rcv.sb_flagsintr & SB_KNOTE) {
                sb->sb_sel.si_note = aso.so_rcv.sb_sel.si_note;
-               sb->sb_flags = SB_KNOTE;
+               sb->sb_flagsintr = SB_KNOTE;
        }
        if (pr->pr_flags & PR_RIGHTS && pr->pr_domain->dom_dispose)
                (*pr->pr_domain->dom_dispose)(aso.so_rcv.sb_mb);
@@ -1178,8 +1178,8 @@ sosplice(struct socket *so, int fd, off_
         * we sleep, the socket buffers are not marked as spliced yet.
         */
        if (somove(so, M_WAIT)) {
-               so->so_rcv.sb_flagsintr |= SB_SPLICE;
-               sosp->so_snd.sb_flagsintr |= SB_SPLICE;
+               so->so_rcv.sb_flags |= SB_SPLICE;
+               sosp->so_snd.sb_flags |= SB_SPLICE;
        }
 
  release:
@@ -1196,8 +1196,8 @@ sounsplice(struct socket *so, struct soc
 
        task_del(sosplice_taskq, &so->so_splicetask);
        timeout_del(&so->so_idleto);
-       sosp->so_snd.sb_flagsintr &= ~SB_SPLICE;
-       so->so_rcv.sb_flagsintr &= ~SB_SPLICE;
+       sosp->so_snd.sb_flags &= ~SB_SPLICE;
+       so->so_rcv.sb_flags &= ~SB_SPLICE;
        so->so_sp->ssp_socket = sosp->so_sp->ssp_soback = NULL;
        if (wakeup && soreadable(so))
                sorwakeup(so);
@@ -1210,7 +1210,7 @@ soidle(void *arg)
        int s;
 
        s = solock(so);
-       if (so->so_rcv.sb_flagsintr & SB_SPLICE) {
+       if (so->so_rcv.sb_flags & SB_SPLICE) {
                so->so_error = ETIMEDOUT;
                sounsplice(so, so->so_sp->ssp_socket, 1);
        }
@@ -1224,7 +1224,7 @@ sotask(void *arg)
        int s;
 
        s = solock(so);
-       if (so->so_rcv.sb_flagsintr & SB_SPLICE) {
+       if (so->so_rcv.sb_flags & SB_SPLICE) {
                /*
                 * We may not sleep here as sofree() and unsplice() may be
                 * called from softnet interrupt context.  This would remove
@@ -1527,7 +1527,7 @@ sorwakeup(struct socket *so)
        soassertlocked(so);
 
 #ifdef SOCKET_SPLICE
-       if (so->so_rcv.sb_flagsintr & SB_SPLICE) {
+       if (so->so_rcv.sb_flags & SB_SPLICE) {
                /*
                 * TCP has a sendbuffer that can handle multiple packets
                 * at once.  So queue the stream a bit to accumulate data.
@@ -1555,7 +1555,7 @@ sowwakeup(struct socket *so)
        soassertlocked(so);
 
 #ifdef SOCKET_SPLICE
-       if (so->so_snd.sb_flagsintr & SB_SPLICE)
+       if (so->so_snd.sb_flags & SB_SPLICE)
                task_add(sosplice_taskq, &so->so_sp->ssp_soback->so_splicetask);
 #endif
        sowakeup(so, &so->so_snd);
@@ -1871,9 +1871,10 @@ sogetopt(struct socket *so, int level, i
 void
 sohasoutofband(struct socket *so)
 {
-       KERNEL_ASSERT_LOCKED();
+       KERNEL_LOCK();
        csignal(so->so_pgid, SIGURG, so->so_siguid, so->so_sigeuid);
        selwakeup(&so->so_rcv.sb_sel);
+       KERNEL_UNLOCK();
 }
 
 int
@@ -1901,7 +1902,7 @@ soo_kqfilter(struct file *fp, struct kno
        }
 
        SLIST_INSERT_HEAD(&sb->sb_sel.si_note, kn, kn_selnext);
-       sb->sb_flags |= SB_KNOTE;
+       sb->sb_flagsintr |= SB_KNOTE;
 
        return (0);
 }
@@ -1915,7 +1916,7 @@ filt_sordetach(struct knote *kn)
 
        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;
+               so->so_rcv.sb_flagsintr &= ~SB_KNOTE;
 }
 
 int
@@ -1958,7 +1959,7 @@ filt_sowdetach(struct knote *kn)
 
        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;
+               so->so_snd.sb_flagsintr &= ~SB_KNOTE;
 }
 
 int
Index: kern/sys_socket.c
===================================================================
RCS file: /cvs/src/sys/kern/sys_socket.c,v
retrieving revision 1.34
diff -u -p -r1.34 sys_socket.c
--- kern/sys_socket.c   14 Nov 2017 16:01:55 -0000      1.34
+++ kern/sys_socket.c   4 Dec 2017 14:20:55 -0000
@@ -166,11 +166,11 @@ soo_poll(struct file *fp, int events, st
        if (revents == 0) {
                if (events & (POLLIN | POLLPRI | POLLRDNORM | POLLRDBAND)) {
                        selrecord(p, &so->so_rcv.sb_sel);
-                       so->so_rcv.sb_flagsintr |= SB_SEL;
+                       so->so_rcv.sb_flags |= SB_SEL;
                }
                if (events & (POLLOUT | POLLWRNORM)) {
                        selrecord(p, &so->so_snd.sb_sel);
-                       so->so_snd.sb_flagsintr |= SB_SEL;
+                       so->so_snd.sb_flags |= SB_SEL;
                }
        }
        sounlock(s);
Index: kern/uipc_socket2.c
===================================================================
RCS file: /cvs/src/sys/kern/uipc_socket2.c,v
retrieving revision 1.87
diff -u -p -r1.87 uipc_socket2.c
--- kern/uipc_socket2.c 23 Nov 2017 13:42:53 -0000      1.87
+++ kern/uipc_socket2.c 4 Dec 2017 14:22:21 -0000
@@ -329,12 +329,12 @@ sosleep(struct socket *so, void *ident, 
 int
 sbwait(struct socket *so, struct sockbuf *sb)
 {
+       int prio = (sb->sb_flags & SB_NOINTR) ? PSOCK : PSOCK | PCATCH;
+
        soassertlocked(so);
 
-       sb->sb_flagsintr |= SB_WAIT;
-       return (sosleep(so, &sb->sb_cc,
-           (sb->sb_flags & SB_NOINTR) ? PSOCK : PSOCK | PCATCH, "netio",
-           sb->sb_timeo));
+       sb->sb_flags |= SB_WAIT;
+       return (sosleep(so, &sb->sb_cc, prio, "netio", sb->sb_timeo));
 }
 
 int
@@ -381,17 +381,18 @@ sbunlock(struct socket *so, struct sockb
 void
 sowakeup(struct socket *so, struct sockbuf *sb)
 {
-       KERNEL_ASSERT_LOCKED();
        soassertlocked(so);
 
-       selwakeup(&sb->sb_sel);
-       sb->sb_flagsintr &= ~SB_SEL;
-       if (sb->sb_flagsintr & SB_WAIT) {
-               sb->sb_flagsintr &= ~SB_WAIT;
+       sb->sb_flags &= ~SB_SEL;
+       if (sb->sb_flags & SB_WAIT) {
+               sb->sb_flags &= ~SB_WAIT;
                wakeup(&sb->sb_cc);
        }
+       KERNEL_LOCK();
        if (so->so_state & SS_ASYNC)
                csignal(so->so_pgid, SIGIO, so->so_siguid, so->so_sigeuid);
+       selwakeup(&sb->sb_sel);
+       KERNEL_UNLOCK();
 }
 
 /*
Index: miscfs/fifofs/fifo_vnops.c
===================================================================
RCS file: /cvs/src/sys/miscfs/fifofs/fifo_vnops.c,v
retrieving revision 1.59
diff -u -p -r1.59 fifo_vnops.c
--- miscfs/fifofs/fifo_vnops.c  4 Nov 2017 14:13:53 -0000       1.59
+++ miscfs/fifofs/fifo_vnops.c  7 Dec 2017 12:31:07 -0000
@@ -307,10 +307,12 @@ fifo_poll(void *v)
        struct socket *wso = ap->a_vp->v_fifoinfo->fi_writesock;
        int events = 0;
        int revents = 0;
+       int s;
 
        /*
         * FIFOs don't support out-of-band or high priority data.
         */
+       s = solock(rso);
        if (ap->a_fflag & FREAD)
                events |= ap->a_events & (POLLIN | POLLRDNORM);
        if (ap->a_fflag & FWRITE)
@@ -333,13 +335,14 @@ fifo_poll(void *v)
                        events = POLLIN;
                if (events & (POLLIN | POLLRDNORM)) {
                        selrecord(ap->a_p, &rso->so_rcv.sb_sel);
-                       rso->so_rcv.sb_flagsintr |= SB_SEL;
+                       rso->so_rcv.sb_flags |= SB_SEL;
                }
                if (events & (POLLOUT | POLLWRNORM)) {
                        selrecord(ap->a_p, &wso->so_snd.sb_sel);
-                       wso->so_snd.sb_flagsintr |= SB_SEL;
+                       wso->so_snd.sb_flags |= SB_SEL;
                }
        }
+       sounlock(s);
        return (revents);
 }
 
@@ -526,7 +529,7 @@ fifo_kqfilter(void *v)
        ap->a_kn->kn_hook = so;
 
        SLIST_INSERT_HEAD(&sb->sb_sel.si_note, ap->a_kn, kn_selnext);
-       sb->sb_flags |= SB_KNOTE;
+       sb->sb_flagsintr |= SB_KNOTE;
 
        return (0);
 }
@@ -538,7 +541,7 @@ filt_fifordetach(struct knote *kn)
 
        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;
+               so->so_rcv.sb_flagsintr &= ~SB_KNOTE;
 }
 
 int
@@ -570,7 +573,7 @@ filt_fifowdetach(struct knote *kn)
 
        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;
+               so->so_snd.sb_flagsintr &= ~SB_KNOTE;
 }
 
 int

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