From: Stephen Hemminger <stephen@networkplumber.org>
Date: Tue, 9 Jan 2018 12:57:32 -0800
Patch-mainline: v4.16-rc1
Subject: uio_hv_generic: add rescind support
Git-commit: ca3cda6fcf1e922213a0cc58e708ffb999151db3
References: fate#323887

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: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Olaf Hering <ohering@suse.de>
---
 drivers/uio/uio_hv_generic.c           | 19 +++++++++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/drivers/uio/uio_hv_generic.c b/drivers/uio/uio_hv_generic.c
--- a/drivers/uio/uio_hv_generic.c
+++ b/drivers/uio/uio_hv_generic.c
@@ -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+ * Callback from vmbus_event when channel is rescinded.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;