Drivers: hv: vmbus: Prevent sending data on a rescinded channel

commit e7e97dd8b77ee7366f2f8c70a033bf5fa05ec2e0 upstream.

After the channel is rescinded, the host does not read from the rescinded channel.
Fail writes to a channel that has already been rescinded. If we permit writes on a
rescinded channel, since the host will not respond we will have situations where
we will be unable to unload vmbus drivers that cannot have any outstanding requests
to the host at the point they are unoaded.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
index 308dbda700ebdaeb02f222aa46dc7bb79c24c0da..e94ed1c22c8b9ce26c4d3c65f7a9c74d7f939649 100644 (file)
--- a/drivers/hv/ring_buffer.c
+++ b/drivers/hv/ring_buffer.c
@@ -298,6 +298,9 @@ int hv_ringbuffer_write(struct vmbus_channel *channel,
        unsigned long flags = 0;
        struct hv_ring_buffer_info *outring_info = &channel->outbound;
 
+       if (channel->rescind)
+               return -ENODEV;
+
        for (i = 0; i < kv_count; i++)
                totalbytes_towrite += kv_list[i].iov_len;
 
@@ -350,6 +353,10 @@ int hv_ringbuffer_write(struct vmbus_channel *channel,
                spin_unlock_irqrestore(&outring_info->ring_lock, flags);
 
        hv_signal_on_write(old_write, channel, kick_q);
+
+       if (channel->rescind)
+               return -ENODEV;
+
        return 0;
 }