Ran into problems with running kqueue/aio with WITNESS etc. Sometimes
things are locked sometimes not. knlist_remove is called telling it
whether it is locked or not ie:
extern void knlist_remove(struct knlist *knl, struct knote *kn, int
islocked);
so I changed:
extern int knlist_empty(struct knlist *knl);
to:
extern int knlist_empty(struct knlist *knl, int islocked);
and then updated things to reflect that following what that state of the
lock for knlist_remove. If it is not locked, it gets a lock and
frees it after.
This now fixes a panic when a process using kqueue/aio is killed on
shutdown with WITNESS.
It changes an API/ABI so it probably can't merged back. If there are
no objections then I'll commit it.
Here is the patch:
Index: fs/fifofs/fifo_vnops.c
===================================================================
RCS file: /cvs/src/sys/fs/fifofs/fifo_vnops.c,v
retrieving revision 1.157
diff -u -p -r1.157 fifo_vnops.c
--- fs/fifofs/fifo_vnops.c 16 Aug 2011 20:07:47 -0000 1.157
+++ fs/fifofs/fifo_vnops.c 26 Jan 2012 20:50:31 -0000
@@ -324,7 +324,7 @@ filt_fifordetach(struct knote *kn)
SOCKBUF_LOCK(&so->so_rcv);
knlist_remove(&so->so_rcv.sb_sel.si_note, kn, 1);
- if (knlist_empty(&so->so_rcv.sb_sel.si_note))
+ if (knlist_empty(&so->so_rcv.sb_sel.si_note, 1))
so->so_rcv.sb_flags &= ~SB_KNOTE;
SOCKBUF_UNLOCK(&so->so_rcv);
}
@@ -352,7 +352,7 @@ filt_fifowdetach(struct knote *kn)
SOCKBUF_LOCK(&so->so_snd);
knlist_remove(&so->so_snd.sb_sel.si_note, kn, 1);
- if (knlist_empty(&so->so_snd.sb_sel.si_note))
+ if (knlist_empty(&so->so_snd.sb_sel.si_note, 1))
so->so_snd.sb_flags &= ~SB_KNOTE;
SOCKBUF_UNLOCK(&so->so_snd);
}
Index: kern/kern_event.c
===================================================================
RCS file: /cvs/src/sys/kern/kern_event.c,v
retrieving revision 1.146
diff -u -p -r1.146 kern_event.c
--- kern/kern_event.c 16 Sep 2011 13:58:51 -0000 1.146
+++ kern/kern_event.c 26 Jan 2012 20:50:31 -0000
@@ -1650,7 +1650,7 @@ kqueue_close(struct file *fp, struct thr
KASSERT(kq->kq_refcnt == 1, ("other refs are out there!"));
fdp = kq->kq_fdp;
- KASSERT(knlist_empty(&kq->kq_sel.si_note),
+ KASSERT(knlist_empty(&kq->kq_sel.si_note, 1),
("kqueue's knlist not empty"));
for (i = 0; i < kq->kq_knlistsize; i++) {
@@ -1735,7 +1735,7 @@ kqueue_wakeup(struct kqueue *kq)
if (!SEL_WAITING(&kq->kq_sel))
kq->kq_state &= ~KQ_SEL;
}
- if (!knlist_empty(&kq->kq_sel.si_note))
+ if (!knlist_empty(&kq->kq_sel.si_note, 1))
kqueue_schedtask(kq);
if ((kq->kq_state & KQ_ASYNC) == KQ_ASYNC) {
pgsigio(&kq->kq_sigio, SIGIO, 0);
@@ -1867,10 +1867,18 @@ knlist_remove_inevent(struct knlist *knl
}
int
-knlist_empty(struct knlist *knl)
+knlist_empty(struct knlist *knl, int knlislocked)
{
- KNL_ASSERT_LOCKED(knl);
- return SLIST_EMPTY(&knl->kl_list);
+ int error;
+
+ KNL_ASSERT_LOCK(knl, knlislocked);
+ if (!knlislocked)
+ knl->kl_lock(knl->kl_lockarg);
+ error = SLIST_EMPTY(&knl->kl_list);
+ if (!knlislocked)
+ knl->kl_unlock(knl->kl_lockarg);
+
+ return error;
}
static struct mtx knlist_lock;
@@ -1931,7 +1939,9 @@ knlist_init(struct knlist *knl, void *lo
else
knl->kl_assert_unlocked = kl_assert_unlocked;
+ knl->kl_lock(knl->kl_lockarg);
SLIST_INIT(&knl->kl_list);
+ knl->kl_unlock(knl->kl_lockarg);
}
void
Index: kern/uipc_socket.c
===================================================================
RCS file: /cvs/src/sys/kern/uipc_socket.c,v
retrieving revision 1.358
diff -u -p -r1.358 uipc_socket.c
--- kern/uipc_socket.c 25 Aug 2011 15:51:54 -0000 1.358
+++ kern/uipc_socket.c 26 Jan 2012 20:50:31 -0000
@@ -3188,7 +3188,7 @@ filt_sordetach(struct knote *kn)
SOCKBUF_LOCK(&so->so_rcv);
knlist_remove(&so->so_rcv.sb_sel.si_note, kn, 1);
- if (knlist_empty(&so->so_rcv.sb_sel.si_note))
+ if (knlist_empty(&so->so_rcv.sb_sel.si_note, 1))
so->so_rcv.sb_flags &= ~SB_KNOTE;
SOCKBUF_UNLOCK(&so->so_rcv);
}
@@ -3222,7 +3222,7 @@ filt_sowdetach(struct knote *kn)
SOCKBUF_LOCK(&so->so_snd);
knlist_remove(&so->so_snd.sb_sel.si_note, kn, 1);
- if (knlist_empty(&so->so_snd.sb_sel.si_note))
+ if (knlist_empty(&so->so_snd.sb_sel.si_note, 1))
so->so_snd.sb_flags &= ~SB_KNOTE;
SOCKBUF_UNLOCK(&so->so_snd);
}
Index: kern/vfs_aio.c
===================================================================
RCS file: /cvs/src/sys/kern/vfs_aio.c,v
retrieving revision 1.249
diff -u -p -r1.249 vfs_aio.c
--- kern/vfs_aio.c 16 Sep 2011 13:58:51 -0000 1.249
+++ kern/vfs_aio.c 26 Jan 2012 20:50:31 -0000
@@ -2531,7 +2533,7 @@ filt_aiodetach(struct knote *kn)
{
struct aiocblist *aiocbe = kn->kn_ptr.p_aio;
- if (!knlist_empty(&aiocbe->klist))
+ if (!knlist_empty(&aiocbe->klist, 0))
knlist_remove(&aiocbe->klist, kn, 0);
}
@@ -2576,7 +2578,7 @@ filt_liodetach(struct knote *kn)
{
struct aioliojob * lj = kn->kn_ptr.p_lio;
- if (!knlist_empty(&lj->klist))
+ if (!knlist_empty(&lj->klist, 0))
knlist_remove(&lj->klist, kn, 0);
}
Index: sys/event.h
===================================================================
RCS file: /cvs/src/sys/sys/event.h,v
retrieving revision 1.49
diff -u -p -r1.49 event.h
--- sys/event.h 31 Dec 2009 20:29:58 -0000 1.49
+++ sys/event.h 26 Jan 2012 20:50:37 -0000
@@ -244,7 +244,7 @@ extern void knote_fork(struct knlist *li
extern void knlist_add(struct knlist *knl, struct knote *kn, int islocked);
extern void knlist_remove(struct knlist *knl, struct knote *kn, int
islocked);
extern void knlist_remove_inevent(struct knlist *knl, struct knote *kn);
-extern int knlist_empty(struct knlist *knl);
+extern int knlist_empty(struct knlist *knl, int islocked);
extern void knlist_init(struct knlist *knl, void *lock,
void (*kl_lock)(void *), void (*kl_unlock)(void *),
void (*kl_assert_locked)(void *), void (*kl_assert_unlocked)(void *));
Thanks,
Doug A.
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