Commit ca3cda6f authored by Stephen Hemminger's avatar Stephen Hemminger Committed by Greg Kroah-Hartman
Browse files

uio_hv_generic: add rescind support 



When host rescinds the device, the UIO driver will clear the interrupt
state and notify application. The read (or write) on the interrupt FD
will then fail with -EIO. This is simpler than adding lots extra uevent
stuff inside UIO.

Signed-off-by: default avatarStephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 06028d15

Documentation/driver-api/uio-howto.rst

+4 −0
Original line number Diff line number Diff line
@@ -698,6 +698,10 @@ prevents the device from generating further interrupts until the bit is 
cleared. The userspace driver should clear this bit before blocking and

waiting for more interrupts.



When host rescinds a device, the interrupt file descriptor is marked down

and any reads of the interrupt file descriptor will return -EIO. Similar

to a closed socket or disconnected serial device.



The vmbus device regions are mapped into uio device resources:

    0) Channel ring buffers: guest to host and host to guest

    1) Guest to host interrupt signalling pages

drivers/uio/uio_hv_generic.c

+19 −0
Original line number Diff line number Diff line
@@ -103,6 +103,23 @@ static void hv_uio_channel_cb(void *context) 
	uio_event_notify(&pdata->info);

}



/*

 * Callback from vmbus_event when channel is rescinded.

 */

static void hv_uio_rescind(struct vmbus_channel *channel)

{

	struct hv_device *hv_dev = channel->primary_channel->device_obj;

	struct hv_uio_private_data *pdata = hv_get_drvdata(hv_dev);



	/*

	 * Turn off the interrupt file handle

	 * Next read for event will return -EIO

	 */

	pdata->info.irq = 0;



	/* Wake up reader */

	uio_event_notify(&pdata->info);

}



static void

hv_uio_cleanup(struct hv_device *dev, struct hv_uio_private_data *pdata)
@@ -218,6 +235,8 @@ hv_uio_probe(struct hv_device *dev, 
		goto fail_close;

	}



	vmbus_set_chn_rescind_callback(dev->channel, hv_uio_rescind);



	hv_set_drvdata(dev, pdata);



	return 0;