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@@ -417,13 +417,24 @@ __hv_pkt_iter_next(struct vmbus_channel *channel,
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}
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EXPORT_SYMBOL_GPL(__hv_pkt_iter_next);
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+/* How many bytes were read in this iterator cycle */
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+static u32 hv_pkt_iter_bytes_read(const struct hv_ring_buffer_info *rbi,
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+ u32 start_read_index)
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+{
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+ if (rbi->priv_read_index >= start_read_index)
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+ return rbi->priv_read_index - start_read_index;
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+ else
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+ return rbi->ring_datasize - start_read_index +
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+ rbi->priv_read_index;
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+}
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+
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/*
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* Update host ring buffer after iterating over packets.
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*/
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void hv_pkt_iter_close(struct vmbus_channel *channel)
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{
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struct hv_ring_buffer_info *rbi = &channel->inbound;
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- u32 orig_write_sz = hv_get_bytes_to_write(rbi);
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+ u32 curr_write_sz, pending_sz, bytes_read, start_read_index;
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/*
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* Make sure all reads are done before we update the read index since
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@@ -431,8 +442,12 @@ void hv_pkt_iter_close(struct vmbus_channel *channel)
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* is updated.
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*/
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virt_rmb();
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+ start_read_index = rbi->ring_buffer->read_index;
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rbi->ring_buffer->read_index = rbi->priv_read_index;
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+ if (!rbi->ring_buffer->feature_bits.feat_pending_send_sz)
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+ return;
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+
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/*
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* Issue a full memory barrier before making the signaling decision.
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* Here is the reason for having this barrier:
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@@ -446,26 +461,29 @@ void hv_pkt_iter_close(struct vmbus_channel *channel)
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*/
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virt_mb();
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- /* If host has disabled notifications then skip */
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- if (rbi->ring_buffer->interrupt_mask)
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+ pending_sz = READ_ONCE(rbi->ring_buffer->pending_send_sz);
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+ if (!pending_sz)
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return;
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- if (rbi->ring_buffer->feature_bits.feat_pending_send_sz) {
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- u32 pending_sz = READ_ONCE(rbi->ring_buffer->pending_send_sz);
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+ /*
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+ * Ensure the read of write_index in hv_get_bytes_to_write()
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+ * happens after the read of pending_send_sz.
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+ */
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+ virt_rmb();
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+ curr_write_sz = hv_get_bytes_to_write(rbi);
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+ bytes_read = hv_pkt_iter_bytes_read(rbi, start_read_index);
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- /*
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- * If there was space before we began iteration,
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- * then host was not blocked. Also handles case where
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- * pending_sz is zero then host has nothing pending
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- * and does not need to be signaled.
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- */
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- if (orig_write_sz > pending_sz)
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- return;
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+ /*
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+ * If there was space before we began iteration,
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+ * then host was not blocked.
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+ */
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- /* If pending write will not fit, don't give false hope. */
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- if (hv_get_bytes_to_write(rbi) < pending_sz)
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- return;
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- }
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+ if (curr_write_sz - bytes_read > pending_sz)
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+ return;
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+
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+ /* If pending write will not fit, don't give false hope. */
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+ if (curr_write_sz <= pending_sz)
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+ return;
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vmbus_setevent(channel);
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}
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