add new system file

hc

2024-02-20 102a0743326a03cd1a1202ceda21e175b7d3575c

 kernel/drivers/hv/ring_buffer.c
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@@ -246,6 +246,19 @@
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 	mutex_unlock(&ring_info->ring_buffer_mutex);
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 }
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+/*
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+ * Check if the ring buffer spinlock is available to take or not; used on
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+ * atomic contexts, like panic path (see the Hyper-V framebuffer driver).
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+ */
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+
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+bool hv_ringbuffer_spinlock_busy(struct vmbus_channel *channel)
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+{
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+	struct hv_ring_buffer_info *rinfo = &channel->outbound;
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+
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+	return spin_is_locked(&rinfo->ring_lock);
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+}
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+EXPORT_SYMBOL_GPL(hv_ringbuffer_spinlock_busy);
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+
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 /* Write to the ring buffer. */
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 int hv_ringbuffer_write(struct vmbus_channel *channel,
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 			const struct kvec *kv_list, u32 kv_count)