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scsi: vmbus: Add function to report available ring buffer to write in total ring size percentage

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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: Long Li <longli@microsoft.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Long Li 2018-03-27 17:48:38 -07:00 committed by Martin K. Petersen
parent b6240a4df0
commit 63273cb401
2 changed files with 14 additions and 0 deletions
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2
drivers/hv/ring_buffer.c
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@ -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);

12
include/linux/hyperv.h
View File

@ -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.