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uio_hv_generic: add rescind support

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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>
This commit is contained in:
Stephen Hemminger 2018-01-09 12:57:32 -08:00 committed by Greg Kroah-Hartman
parent 06028d1517
commit ca3cda6fcf
2 changed files with 23 additions and 0 deletions
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4
Documentation/driver-api/uio-howto.rst
View File

@ -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

19
drivers/uio/uio_hv_generic.c
View File

@ -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* Callback from vmbus_event when channel is rescinded.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;