EHCI: Do not ignore status of PrepareKernelAccess.

May help with #17799.

src/add-ons/kernel/busses/usb/ehci.cpp

@@ -1887,11 +1887,13 @@ EHCI::FinishTransfers()
 						// data to read out
 						iovec *vector = transfer->transfer->Vector();
 						size_t vectorCount = transfer->transfer->VectorCount();
-						transfer->transfer->PrepareKernelAccess();
+						callbackStatus = transfer->transfer->PrepareKernelAccess();
+						if (callbackStatus == B_OK) {
 							actualLength = ReadDescriptorChain(
 								transfer->data_descriptor,
 								vector, vectorCount,
 								&nextDataToggle);
+						}
 					} else if (transfer->data_descriptor) {
 						// calculate transfered length
 						actualLength = ReadActualLength(
@@ -1900,8 +1902,9 @@ EHCI::FinishTransfers()
 
 					transfer->transfer->TransferPipe()->SetDataToggle(
 						nextDataToggle);
+				}
 
-					if (transfer->transfer->IsFragmented()) {
+				if (callbackStatus == B_OK && transfer->transfer->IsFragmented()) {
 					// this transfer may still have data left
 					transfer->transfer->AdvanceByFragment(actualLength);
 					if (transfer->transfer->FragmentLength() > 0) {
@@ -1930,7 +1933,6 @@ EHCI::FinishTransfers()
 					// actualLength with AdvanceByFragment()
 					actualLength = 0;
 				}
-				}
 
 				transfer->transfer->Finished(callbackStatus, actualLength);
 				fProcessingPipe = NULL;
@@ -2057,8 +2059,10 @@ EHCI::FinishIsochronousTransfers()
 				if (transfer && transfer->is_active) {
 					TRACE("FinishIsochronousTransfers active transfer\n");
 					size_t actualLength = 0;
+					status_t status = B_OK;
 					if (((itd->buffer_phy[1] >> EHCI_ITD_DIR_SHIFT) & 1) != 0) {
-						transfer->transfer->PrepareKernelAccess();
+						status = transfer->transfer->PrepareKernelAccess();
+						if (status == B_OK)
 							actualLength = ReadIsochronousDescriptorChain(transfer);
 					}
 
@@ -2080,7 +2084,7 @@ EHCI::FinishIsochronousTransfers()
 					}
 					transfer->link = NULL;
 
-					transfer->transfer->Finished(B_OK, actualLength);
+					transfer->transfer->Finished(status, actualLength);
 
 					itd = itd->prev;
 
@@ -2344,8 +2348,14 @@ EHCI::FillQueueWithRequest(Transfer *transfer, ehci_qh *queueHead,
 		}
 
 		if (!directionIn) {
-			if (prepareKernelAccess)
-				transfer->PrepareKernelAccess();
+			if (prepareKernelAccess) {
+				result = transfer->PrepareKernelAccess();
+				if (result != B_OK) {
+					FreeDescriptor(setupDescriptor);
+					FreeDescriptor(statusDescriptor);
+					return result;
+				}
+			}
 			WriteDescriptorChain(dataDescriptor, transfer->Vector(),
 				transfer->VectorCount());
 		}
@@ -2386,8 +2396,13 @@ EHCI::FillQueueWithData(Transfer *transfer, ehci_qh *queueHead,
 
 	lastDescriptor->token |= EHCI_QTD_IOC;
 	if (!directionIn) {
-		if (prepareKernelAccess)
-			transfer->PrepareKernelAccess();
+		if (prepareKernelAccess) {
+			result = transfer->PrepareKernelAccess();
+			if (result != B_OK) {
+				FreeDescriptorChain(firstDescriptor);
+				return result;
+			}
+		}
 		WriteDescriptorChain(firstDescriptor, transfer->Vector(),
 			transfer->VectorCount());
 	}