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Commit 63273cb4 authored by Long Li's avatar Long Li Committed by Martin K. Petersen
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scsi: vmbus: Add function to report available ring buffer to write in total ring size percentage 



Netvsc has a function to calculate how much ring buffer in percentage is
available to write. This function is also useful for storvsc and other
vmbus devices.

Define a similar function in vmbus to be used by other vmbus devices.

Signed-off-by: default avatarLong Li <longli@microsoft.com>
Acked-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent b6240a4d

drivers/hv/ring_buffer.c

+2 −0
Original line number Diff line number Diff line
@@ -227,6 +227,8 @@ int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info, 
	ring_info->ring_buffer->feature_bits.value = 1;



	ring_info->ring_size = page_cnt << PAGE_SHIFT;

	ring_info->ring_size_div10_reciprocal =

		reciprocal_value(ring_info->ring_size / 10);

	ring_info->ring_datasize = ring_info->ring_size -

		sizeof(struct hv_ring_buffer);

include/linux/hyperv.h

+12 −0
Original line number Diff line number Diff line
@@ -35,6 +35,7 @@ 
#include <linux/device.h>

#include <linux/mod_devicetable.h>

#include <linux/interrupt.h>

#include <linux/reciprocal_div.h>



#define MAX_PAGE_BUFFER_COUNT				32

#define MAX_MULTIPAGE_BUFFER_COUNT			32 /* 128K */
@@ -120,6 +121,7 @@ struct hv_ring_buffer { 
struct hv_ring_buffer_info {

	struct hv_ring_buffer *ring_buffer;

	u32 ring_size;			/* Include the shared header */

	struct reciprocal_value ring_size_div10_reciprocal;

	spinlock_t ring_lock;



	u32 ring_datasize;		/* < ring_size */
@@ -154,6 +156,16 @@ static inline u32 hv_get_bytes_to_write(const struct hv_ring_buffer_info *rbi) 
	return write;

}



static inline u32 hv_get_avail_to_write_percent(

		const struct hv_ring_buffer_info *rbi)

{

	u32 avail_write = hv_get_bytes_to_write(rbi);



	return reciprocal_divide(

			(avail_write  << 3) + (avail_write << 1),

			rbi->ring_size_div10_reciprocal);

}



/*

 * VMBUS version is 32 bit entity broken up into

 * two 16 bit quantities: major_number. minor_number.