Drivers: hv: vmbus: Prevent sending data on a rescinded channel

After the channel is rescinded, the host does not read from the rescinded channel.
Fail writes to a channel that has already been rescinded.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rescinded channel, since the host will not respond we will have situations where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>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
index cd49cb17eb7fb385ddbf507ef14b2ea2be090159..2cd40298685862bb8ad9b87a6cc57cd21888c64a 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;
 }