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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [win-pv-devel] [PATCH 14/15] Re-work EVTCHN Close
When using the FIFO ABI, the Close operation needs to be synchronized with
polling. This requires some re-structuring of the close code to defer the
actual closure of the event channel in Xen until at least one poll after
masking and starting the tear-down.
Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
---
src/xenbus/evtchn.c | 249 +++++++++++++++++++++++++++++++++-------------------
1 file changed, 161 insertions(+), 88 deletions(-)
diff --git a/src/xenbus/evtchn.c b/src/xenbus/evtchn.c
index 437bfac..dd608ba 100644
--- a/src/xenbus/evtchn.c
+++ b/src/xenbus/evtchn.c
@@ -85,6 +85,7 @@ struct _XENBUS_EVTCHN_CHANNEL {
BOOLEAN Mask;
ULONG LocalPort;
ULONG Cpu;
+ BOOLEAN Closed;
};
struct _XENBUS_EVTCHN_CONTEXT {
@@ -310,6 +311,8 @@ EvtchnOpen(
LocalPort = Channel->LocalPort;
+ Trace("%u\n", LocalPort);
+
InitializeListHead(&Channel->PendingListEntry);
status = XENBUS_EVTCHN_ABI(PortEnable,
@@ -378,63 +381,49 @@ fail1:
return NULL;
}
-static NTSTATUS
-EvtchnBind(
- IN PINTERFACE Interface,
+static VOID
+EvtchnReap(
+ IN PXENBUS_EVTCHN_CONTEXT Context,
IN PXENBUS_EVTCHN_CHANNEL Channel,
- IN ULONG Cpu
+ IN BOOLEAN Close
)
{
- PXENBUS_EVTCHN_CONTEXT Context = Interface->Context;
- ULONG LocalPort;
- unsigned int vcpu_id;
- KIRQL Irql;
- NTSTATUS status;
+ ULONG LocalPort = Channel->LocalPort;
- status = STATUS_INVALID_PARAMETER;
- if (Cpu >= (ULONG)KeNumberProcessors)
- goto fail1;
-
- status = STATUS_NOT_SUPPORTED;
- if (~Context->Affinity & ((KAFFINITY)1 << Cpu))
- goto fail2;
-
- KeAcquireSpinLock(&Channel->Lock, &Irql);
-
- if (!Channel->Active)
- goto done;
+ UNREFERENCED_PARAMETER(Context);
- if (Channel->Cpu == Cpu)
- goto done;
+ Trace("%u\n", LocalPort);
- LocalPort = Channel->LocalPort;
- vcpu_id = SystemVirtualCpuIndex(Cpu);
+ ASSERT(Channel->Closed);
+ Channel->Closed = FALSE;
- status = EventChannelBindVirtualCpu(LocalPort, vcpu_id);
- if (!NT_SUCCESS(status))
- goto fail3;
+ RtlZeroMemory(&Channel->Lock, sizeof (KSPIN_LOCK));
- Channel->Cpu = Cpu;
+ RemoveEntryList(&Channel->ListEntry);
+ RtlZeroMemory(&Channel->ListEntry, sizeof (LIST_ENTRY));
- Info("[%u]: CPU %u\n", LocalPort, Cpu);
+ Channel->Cpu = 0;
-done:
- KeReleaseSpinLock(&Channel->Lock, Irql);
+ ASSERT(IsListEmpty(&Channel->PendingListEntry));
+ RtlZeroMemory(&Channel->PendingListEntry, sizeof (LIST_ENTRY));
- return STATUS_SUCCESS;
+ Channel->LocalPort = 0;
+ Channel->Mask = FALSE;
+ RtlZeroMemory(&Channel->Parameters, sizeof (XENBUS_EVTCHN_PARAMETERS));
-fail3:
- Error("fail3\n");
+ if (Close && Channel->Type != XENBUS_EVTCHN_TYPE_FIXED)
+ (VOID) EventChannelClose(LocalPort);
- KeReleaseSpinLock(&Channel->Lock, Irql);
+ Channel->Argument = NULL;
+ Channel->Callback = NULL;
+ Channel->Type = 0;
-fail2:
- Error("fail2\n");
+ Channel->Caller = NULL;
-fail1:
- Error("fail1 (%08x)\n", status);
+ Channel->Magic = 0;
- return status;
+ ASSERT(IsZeroMemory(Channel, sizeof (XENBUS_EVTCHN_CHANNEL)));
+ __EvtchnFree(Channel);
}
static BOOLEAN
@@ -473,10 +462,12 @@ done:
static BOOLEAN
EvtchnPoll(
IN PXENBUS_EVTCHN_CONTEXT Context,
- IN ULONG Cpu
+ IN ULONG Cpu,
+ IN PLIST_ENTRY List
)
{
BOOLEAN DoneSomething;
+ PLIST_ENTRY ListEntry;
(VOID) XENBUS_EVTCHN_ABI(Poll,
&Context->EvtchnAbi,
@@ -485,29 +476,40 @@ EvtchnPoll(
Context);
DoneSomething = FALSE;
- while (!IsListEmpty(&Context->PendingList[Cpu])) {
- PLIST_ENTRY ListEntry;
- PXENBUS_EVTCHN_CHANNEL Channel;
-
- ListEntry = RemoveHeadList(&Context->PendingList[Cpu]);
- ASSERT(ListEntry != &Context->PendingList[Cpu]);
- InitializeListHead(ListEntry);
+ ListEntry = Context->PendingList[Cpu].Flink;
+ while (ListEntry != &Context->PendingList[Cpu]) {
+ PLIST_ENTRY Next = ListEntry->Flink;
+ PXENBUS_EVTCHN_CHANNEL Channel;
Channel = CONTAINING_RECORD(ListEntry,
XENBUS_EVTCHN_CHANNEL,
PendingListEntry);
- if (Channel->Mask)
- XENBUS_EVTCHN_ABI(PortMask,
+
+ ASSERT3U(Channel->Magic, ==, XENBUS_EVTCHN_CHANNEL_MAGIC);
+
+ KeMemoryBarrier();
+ if (!Channel->Closed) {
+ RemoveEntryList(&Channel->PendingListEntry);
+ InitializeListHead(&Channel->PendingListEntry);
+
+ if (Channel->Mask)
+ XENBUS_EVTCHN_ABI(PortMask,
+ &Context->EvtchnAbi,
+ Channel->LocalPort);
+
+ XENBUS_EVTCHN_ABI(PortAck,
&Context->EvtchnAbi,
Channel->LocalPort);
- XENBUS_EVTCHN_ABI(PortAck,
- &Context->EvtchnAbi,
- Channel->LocalPort);
-
#pragma warning(suppress:6387) // NULL argument
- DoneSomething |= Channel->Callback(NULL, Channel->Argument);
+ DoneSomething |= Channel->Callback(NULL, Channel->Argument);
+ } else if (List != NULL) {
+ RemoveEntryList(&Channel->PendingListEntry);
+ InsertTailList(List, &Channel->PendingListEntry);
+ }
+
+ ListEntry = Next;
}
return DoneSomething;
@@ -519,6 +521,7 @@ EvtchnFlush(
IN ULONG Cpu
)
{
+ LIST_ENTRY List;
PXENBUS_INTERRUPT Interrupt;
KIRQL Irql;
@@ -526,11 +529,31 @@ EvtchnFlush(
Context->LatchedInterrupt[Cpu] :
Context->LevelSensitiveInterrupt;
+ InitializeListHead(&List);
+
Irql = FdoAcquireInterruptLock(Context->Fdo, Interrupt);
- (VOID) EvtchnPoll(Context, Cpu);
+ (VOID) EvtchnPoll(Context, Cpu, &List);
FdoReleaseInterruptLock(Context->Fdo, Interrupt, Irql);
+
+ while (!IsListEmpty(&List)) {
+ PLIST_ENTRY ListEntry;
+ PXENBUS_EVTCHN_CHANNEL Channel;
+
+ ListEntry = RemoveHeadList(&List);
+ ASSERT(ListEntry != &List);
+
+ Channel = CONTAINING_RECORD(ListEntry,
+ XENBUS_EVTCHN_CHANNEL,
+ PendingListEntry);
+
+ ASSERT3U(Channel->Magic, ==, XENBUS_EVTCHN_CHANNEL_MAGIC);
+
+ InitializeListHead(&Channel->PendingListEntry);
+
+ EvtchnReap(Context, Channel, TRUE);
+ }
}
static
@@ -608,6 +631,65 @@ EvtchnTrigger(
KeInsertQueueDpc(Dpc, NULL, NULL);
}
+static NTSTATUS
+EvtchnBind(
+ IN PINTERFACE Interface,
+ IN PXENBUS_EVTCHN_CHANNEL Channel,
+ IN ULONG Cpu
+ )
+{
+ PXENBUS_EVTCHN_CONTEXT Context = Interface->Context;
+ ULONG LocalPort;
+ unsigned int vcpu_id;
+ KIRQL Irql;
+ NTSTATUS status;
+
+ status = STATUS_INVALID_PARAMETER;
+ if (Cpu >= (ULONG)KeNumberProcessors)
+ goto fail1;
+
+ status = STATUS_NOT_SUPPORTED;
+ if (~Context->Affinity & ((KAFFINITY)1 << Cpu))
+ goto fail2;
+
+ KeAcquireSpinLock(&Channel->Lock, &Irql);
+
+ if (!Channel->Active)
+ goto done;
+
+ if (Channel->Cpu == Cpu)
+ goto done;
+
+ LocalPort = Channel->LocalPort;
+ vcpu_id = SystemVirtualCpuIndex(Cpu);
+
+ status = EventChannelBindVirtualCpu(LocalPort, vcpu_id);
+ if (!NT_SUCCESS(status))
+ goto fail3;
+
+ Channel->Cpu = Cpu;
+
+ Info("[%u]: CPU %u\n", LocalPort, Cpu);
+
+done:
+ KeReleaseSpinLock(&Channel->Lock, Irql);
+
+ return STATUS_SUCCESS;
+
+fail3:
+ Error("fail3\n");
+
+ KeReleaseSpinLock(&Channel->Lock, Irql);
+
+fail2:
+ Error("fail2\n");
+
+fail1:
+ Error("fail1 (%08x)\n", status);
+
+ return status;
+}
+
static VOID
EvtchnUnmask(
IN PINTERFACE Interface,
@@ -688,57 +770,48 @@ EvtchnClose(
)
{
PXENBUS_EVTCHN_CONTEXT Context = Interface->Context;
+ ULONG LocalPort = Channel->LocalPort;
KIRQL Irql;
ASSERT3U(Channel->Magic, ==, XENBUS_EVTCHN_CHANNEL_MAGIC);
- RtlZeroMemory(&Channel->Lock, sizeof (KSPIN_LOCK));
-
KeRaiseIrql(DISPATCH_LEVEL, &Irql); // Prevent suspend
- KeAcquireSpinLockAtDpcLevel(&Context->Lock);
- RemoveEntryList(&Channel->ListEntry);
- KeReleaseSpinLockFromDpcLevel(&Context->Lock);
-
- RtlZeroMemory(&Channel->ListEntry, sizeof (LIST_ENTRY));
+ Trace("%u\n", LocalPort);
if (Channel->Active) {
- ULONG LocalPort = Channel->LocalPort;
NTSTATUS status;
Channel->Active = FALSE;
- XENBUS_EVTCHN_ABI(PortMask,
+ XENBUS_EVTCHN_ABI(PortDisable,
&Context->EvtchnAbi,
LocalPort);
- if (Channel->Type != XENBUS_EVTCHN_TYPE_FIXED)
- (VOID) EventChannelClose(LocalPort);
-
status = HashTableRemove(Context->Table, LocalPort);
ASSERT(NT_SUCCESS(status));
- }
- Channel->Cpu = 0;
+ //
+ // The event may be pending on a CPU queue so we mark it as
+ // closed but defer the rest of the work to the correct
+ // DPC, which will make sure the queue is polled first.
+ //
- ASSERT(IsListEmpty(&Channel->PendingListEntry));
- RtlZeroMemory(&Channel->PendingListEntry, sizeof (LIST_ENTRY));
+ Channel->Closed = TRUE;
+ KeMemoryBarrier();
- Channel->LocalPort = 0;
- Channel->Mask = FALSE;
- RtlZeroMemory(&Channel->Parameters, sizeof (XENBUS_EVTCHN_PARAMETERS));
-
- Channel->Argument = NULL;
- Channel->Callback = NULL;
- Channel->Type = 0;
+ EvtchnTrigger(Interface, Channel);
+ goto done;
+ }
- Channel->Caller = NULL;
+ KeAcquireSpinLockAtDpcLevel(&Context->Lock);
- Channel->Magic = 0;
+ Channel->Closed = TRUE;
+ EvtchnReap(Context, Channel, FALSE);
- ASSERT(IsZeroMemory(Channel, sizeof (XENBUS_EVTCHN_CHANNEL)));
- __EvtchnFree(Channel);
+ KeReleaseSpinLockFromDpcLevel(&Context->Lock);
+done:
KeLowerIrql(Irql);
}
@@ -778,7 +851,7 @@ EvtchnInterruptCallback(
while (XENBUS_SHARED_INFO(UpcallPending,
&Context->SharedInfoInterface,
Cpu))
- DoneSomething |= EvtchnPoll(Context, Cpu);
+ DoneSomething |= EvtchnPoll(Context, Cpu, NULL);
return DoneSomething;
}
@@ -1203,9 +1276,6 @@ EvtchnRelease(
Trace("====>\n");
- if (!IsListEmpty(&Context->List))
- BUG("OUTSTANDING EVENT CHANNELS");
-
EvtchnInterruptDisable(Context);
Cpu = KeNumberProcessors;
@@ -1219,6 +1289,9 @@ EvtchnRelease(
FdoFreeInterrupt(Fdo, Context->LevelSensitiveInterrupt);
Context->LevelSensitiveInterrupt = NULL;
+ if (!IsListEmpty(&Context->List))
+ BUG("OUTSTANDING EVENT CHANNELS");
+
EvtchnAbiRelease(Context);
XENBUS_SHARED_INFO(Release, &Context->SharedInfoInterface);
--
2.1.1
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