Author: sephe
Date: Thu Nov 24 06:01:29 2016
New Revision: 309083
URL: https://svnweb.freebsd.org/changeset/base/309083
Log:
hyperv/vmbus: Fix the multi-channel revoking on vmbus side.
- Reference count the sub-channel when channel offer message is
processed, so that immediate rescind message on the same channel
will not race sub-channel open on driver side.
- Drop the above reference when sub-channel is closed, this closely
mimics the hypervisor's reaction when primary channel is closed
on the VM side. No drivers use sub-channel after primary channel
is closed.
MFC after: 1 week
Sponsored by: Microsoft
Differential Revision: https://reviews.freebsd.org/D8546
Modified:
head/sys/dev/hyperv/vmbus/vmbus_chan.c
head/sys/dev/hyperv/vmbus/vmbus_chanvar.h
Modified: head/sys/dev/hyperv/vmbus/vmbus_chan.c
==============================================================================
--- head/sys/dev/hyperv/vmbus/vmbus_chan.c Thu Nov 24 05:52:28 2016
(r309082)
+++ head/sys/dev/hyperv/vmbus/vmbus_chan.c Thu Nov 24 06:01:29 2016
(r309083)
@@ -65,6 +65,7 @@ static void vmbus_chan_cpu_default(str
static int vmbus_chan_release(struct vmbus_channel *);
static void vmbus_chan_set_chmap(struct vmbus_channel *);
static void vmbus_chan_clear_chmap(struct vmbus_channel *);
+static void vmbus_chan_detach(struct vmbus_channel *);
static void vmbus_chan_ins_prilist(struct vmbus_softc *,
struct vmbus_channel *);
@@ -628,6 +629,32 @@ vmbus_chan_gpadl_disconnect(struct vmbus
}
static void
+vmbus_chan_detach(struct vmbus_channel *chan)
+{
+ int refs;
+
+ KASSERT(chan->ch_refs > 0, ("chan%u: invalid refcnt %d",
+ chan->ch_id, chan->ch_refs));
+ refs = atomic_fetchadd_int(&chan->ch_refs, -1);
+#ifdef INVARIANTS
+ if (VMBUS_CHAN_ISPRIMARY(chan)) {
+ KASSERT(refs == 1, ("chan%u: invalid refcnt %d for prichan",
+ chan->ch_id, refs + 1));
+ }
+#endif
+ if (refs == 1) {
+ /*
+ * Detach the target channel.
+ */
+ if (bootverbose) {
+ vmbus_chan_printf(chan, "chan%u detached\n",
+ chan->ch_id);
+ }
+ taskqueue_enqueue(chan->ch_mgmt_tq, &chan->ch_detach_task);
+ }
+}
+
+static void
vmbus_chan_clrchmap_task(void *xchan, int pending __unused)
{
struct vmbus_channel *chan = xchan;
@@ -752,8 +779,15 @@ vmbus_chan_close(struct vmbus_channel *c
int i;
subchan = vmbus_subchan_get(chan, subchan_cnt);
- for (i = 0; i < subchan_cnt; ++i)
+ for (i = 0; i < subchan_cnt; ++i) {
vmbus_chan_close_internal(subchan[i]);
+ /*
+ * This sub-channel is referenced, when it is
+ * linked to the primary channel; drop that
+ * reference now.
+ */
+ vmbus_chan_detach(subchan[i]);
+ }
vmbus_subchan_rel(subchan, subchan_cnt);
}
@@ -1114,6 +1148,7 @@ vmbus_chan_alloc(struct vmbus_softc *sc)
return NULL;
}
+ chan->ch_refs = 1;
chan->ch_vmbus = sc;
mtx_init(&chan->ch_subchan_lock, "vmbus subchan", NULL, MTX_DEF);
sx_init(&chan->ch_orphan_lock, "vmbus chorphan");
@@ -1137,6 +1172,8 @@ vmbus_chan_free(struct vmbus_channel *ch
VMBUS_CHAN_ST_ONLIST)) == 0, ("free busy channel"));
KASSERT(chan->ch_orphan_xact == NULL,
("still has orphan xact installed"));
+ KASSERT(chan->ch_refs == 0, ("chan%u: invalid refcnt %d",
+ chan->ch_id, chan->ch_refs));
hyperv_dmamem_free(&chan->ch_monprm_dma, chan->ch_monprm);
mtx_destroy(&chan->ch_subchan_lock);
@@ -1213,6 +1250,14 @@ vmbus_chan_add(struct vmbus_channel *new
("new channel is not sub-channel"));
KASSERT(prichan != NULL, ("no primary channel"));
+ /*
+ * Reference count this sub-channel; it will be dereferenced
+ * when this sub-channel is closed.
+ */
+ KASSERT(newchan->ch_refs == 1, ("chan%u: invalid refcnt %d",
+ newchan->ch_id, newchan->ch_refs));
+ atomic_add_int(&newchan->ch_refs, 1);
+
newchan->ch_prichan = prichan;
newchan->ch_dev = prichan->ch_dev;
@@ -1359,6 +1404,7 @@ vmbus_chan_msgproc_choffer(struct vmbus_
if (error) {
device_printf(sc->vmbus_dev, "add chan%u failed: %d\n",
chan->ch_id, error);
+ atomic_subtract_int(&chan->ch_refs, 1);
vmbus_chan_free(chan);
return;
}
@@ -1426,9 +1472,7 @@ vmbus_chan_msgproc_chrescind(struct vmbu
if (bootverbose)
vmbus_chan_printf(chan, "chan%u revoked\n", note->chm_chanid);
-
- /* Detach the target channel. */
- taskqueue_enqueue(chan->ch_mgmt_tq, &chan->ch_detach_task);
+ vmbus_chan_detach(chan);
}
static int
Modified: head/sys/dev/hyperv/vmbus/vmbus_chanvar.h
==============================================================================
--- head/sys/dev/hyperv/vmbus/vmbus_chanvar.h Thu Nov 24 05:52:28 2016
(r309082)
+++ head/sys/dev/hyperv/vmbus/vmbus_chanvar.h Thu Nov 24 06:01:29 2016
(r309083)
@@ -142,6 +142,8 @@ struct vmbus_channel {
struct sx ch_orphan_lock;
struct vmbus_xact_ctx *ch_orphan_xact;
+ int ch_refs;
+
struct sysctl_ctx_list ch_sysctl_ctx;
} __aligned(CACHE_LINE_SIZE);
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