#include <linux/module.h>
#include <linux/hyperv.h>
#include <linux/uio.h>
+#include <linux/interrupt.h>
#include "hyperv_vmbus.h"
static int vmbus_close_internal(struct vmbus_channel *channel)
{
struct vmbus_channel_close_channel *msg;
+ struct tasklet_struct *tasklet;
int ret;
+ /*
+ * process_chn_event(), running in the tasklet, can race
+ * with vmbus_close_internal() in the case of SMP guest, e.g., when
+ * the former is accessing channel->inbound.ring_buffer, the latter
+ * could be freeing the ring_buffer pages.
+ *
+ * To resolve the race, we can serialize them by disabling the
+ * tasklet when the latter is running here.
+ */
+ tasklet = hv_context.event_dpc[channel->target_cpu];
+ tasklet_disable(tasklet);
+
channel->state = CHANNEL_OPEN_STATE;
channel->sc_creation_callback = NULL;
/* Stop callback and cancel the timer asap */
* If we failed to post the close msg,
* it is perhaps better to leak memory.
*/
- return ret;
+ goto out;
}
/* Tear down the gpadl for the channel's ring buffer */
* If we failed to teardown gpadl,
* it is perhaps better to leak memory.
*/
- return ret;
+ goto out;
}
}
free_pages((unsigned long)channel->ringbuffer_pages,
get_order(channel->ringbuffer_pagecount * PAGE_SIZE));
- /*
- * If the channel has been rescinded; process device removal.
- */
- if (channel->rescind)
- hv_process_channel_removal(channel,
- channel->offermsg.child_relid);
+out:
+ tasklet_enable(tasklet);
+
return ret;
}
* on the ring. We will not signal if more data is
* to be placed.
*
+ * Based on the channel signal state, we will decide
+ * which signaling policy will be applied.
+ *
* If we cannot write to the ring-buffer; signal the host
* even if we may not have written anything. This is a rare
* enough condition that it should not matter.
*/
+
+ if (channel->signal_policy)
+ signal = true;
+ else
+ kick_q = true;
+
if (((ret == 0) && kick_q && signal) || (ret))
vmbus_setevent(channel);
* on the ring. We will not signal if more data is
* to be placed.
*
+ * Based on the channel signal state, we will decide
+ * which signaling policy will be applied.
+ *
* If we cannot write to the ring-buffer; signal the host
* even if we may not have written anything. This is a rare
* enough condition that it should not matter.
*/
+
+ if (channel->signal_policy)
+ signal = true;
+ else
+ kick_q = true;
+
if (((ret == 0) && kick_q && signal) || (ret))
vmbus_setevent(channel);