Commit 78033b77 authored Nov 07, 2024 by tomm Committed by Tom Mulcahy Dec 02, 2024

usb: Use Get/SetByteArrayRegion in controlTransfer

This change replaces
GetPrimitiveArrayCritical/ReleasePrimitiveArrayCritical with
GetByteArrayRegion/SetByteArrayRegion.

This change is needed because the critical API variants are not
appropriate for this context. See the JNI docs:

"After calling GetPrimitiveArrayCritical, the native code should not run
for an extended period of time before it calls
ReleasePrimitiveArrayCritical."

In controlTransfer, we call usb_device_control_transfer between
GetPrimitiveArrayCritical/ReleasePrimitiveArrayCritical.
usb_device_control_transfer is a blocking call so this can lead to GC
hangs.

Instead, we allocate a new buffer and then call
GetByteArrayRegion/SetByteArrayRegion before/after
usb_device_control_transfer, depending on the direction of the endpoint.

This change is analogous to
https://android-review.googlesource.com/c/platform/frameworks/base/+/3056082
which fixed the same problem in bulkTransfer.

Test: I ran the USB Accessory Test - https://source.android.com/docs/compatibility/cts/verifier#testing-accessory-8 - both directions (this change on the DUT and this change on the companion device)

Change-Id: I3f670121fc1c65f046376aa819d638edb446658a

parent 2e1a903f

core/jni/android_hardware_UsbDeviceConnection.cpp

+14 −8

Original line number	Diff line number	Diff line
		@@ -165,19 +165,25 @@ android_hardware_UsbDeviceConnection_control_request(JNIEnv *env, jobject thiz,
		return -1;
		}

		jbyte* bufferBytes = NULL;
		if (buffer) {
		bufferBytes = (jbyte*)env->GetPrimitiveArrayCritical(buffer, NULL);
		bool is_dir_in = (requestType & USB_ENDPOINT_DIR_MASK) == USB_DIR_IN;
		std::unique_ptr<jbyte[]> bufferBytes(new (std::nothrow) jbyte[length]);
		if (!bufferBytes) {
		jniThrowException(env, "java/lang/OutOfMemoryError", NULL);
		return -1;
		}

		jint result = usb_device_control_transfer(device, requestType, request,
		value, index, bufferBytes + start, length, timeout);
		if (!is_dir_in && buffer) {
		env->GetByteArrayRegion(buffer, start, length, bufferBytes.get());
		}

		if (bufferBytes) {
		env->ReleasePrimitiveArrayCritical(buffer, bufferBytes, 0);
		jint bytes_transferred = usb_device_control_transfer(device, requestType, request,
		value, index, bufferBytes.get(), length, timeout);

		if (bytes_transferred > 0 && is_dir_in) {
		env->SetByteArrayRegion(buffer, start, bytes_transferred, bufferBytes.get());
		}

		return result;
		return bytes_transferred;
		}

		static jint