DebugPrintV first locks print_sem, and then locks io_sem.
async_io, locks io_sem.
In ordr to avoid a deadlock, DebugPrintV MUSTN'T be called when
io_sem is locked.
Also notice, that locking io_sem during DebugPrintV limits our ability
to use the log_port for debugging concurrency problems related to ios.
---
xddm/display/qxldd.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/xddm/display/qxldd.h b/xddm/display/qxldd.h
index 1a1b5d5..362c293 100644
--- a/xddm/display/qxldd.h
+++ b/xddm/display/qxldd.h
@@ -474,6 +474,7 @@ static _inline void async_io(PDev *pdev, asyncable_t op, UCHAR val)
ULONG64 millis;
if (pdev->use_async) {
+ DEBUG_PRINT((pdev, 3, "%s: start async %d\n", __FUNCTION__, (int)op));
EngAcquireSemaphore(pdev->io_sem);
WRITE_PORT_UCHAR(pdev->asyncable[op][ASYNC], val);
/* Our Interrupt may be taken from us unexpectedly, by a surprise removal.
@@ -482,7 +483,6 @@ static _inline void async_io(PDev *pdev, asyncable_t op, UCHAR val)
* we get reset. We use EngQueryLocalTime because there is no way to differentiate a return on
* timeout from a return on event set otherwise. */
timeout.QuadPart = -INTERRUPT_NOT_PRESENT_TIMEOUT_100NS; // negative => relative
- DEBUG_PRINT((pdev, 15, "WAIT_FOR_EVENT %d\n", (int)op));
EngQueryLocalTime(&start);
WAIT_FOR_EVENT(pdev, pdev->io_cmd_event, &timeout);
EngQueryLocalTime(&finish);
@@ -492,7 +492,7 @@ static _inline void async_io(PDev *pdev, asyncable_t op, UCHAR val)
DEBUG_PRINT((pdev, 0, "%s: timeout reached, disabling async io!\n", __FUNCTION__));
}
EngReleaseSemaphore(pdev->io_sem);
- DEBUG_PRINT((pdev, 3, "finished async %d\n", (int)op));
+ DEBUG_PRINT((pdev, 3, "%s: finished async %d\n", __FUNCTION__, (int)op));
} else {
if (pdev->asyncable[op][SYNC] == NULL) {
DEBUG_PRINT((pdev, 0, "ERROR: trying calling sync io on NULL port %d\n", op));
--
1.8.1.4
_______________________________________________
Spice-devel mailing list
Spice-devel@xxxxxxxxxxxxxxxxxxxxx
http://lists.freedesktop.org/mailman/listinfo/spice-devel