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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: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
hifive-unleashed-5.1
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* Callback from vmbus_event when channel is rescinded.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;