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Drivers: hv: vmbus: Introduce functions for estimating room in the ring buffer

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Introduce separate functions for estimating how much can be read from
and written to the ring buffer.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
K. Y. Srinivasan
2016-04-02 17:59:46 -07:00
committed by Greg Kroah-Hartman
parent a389fcfd2c
commit a6341f0000
2 changed files with 31 additions and 21 deletions
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27
include/linux/hyperv.h
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@@ -151,6 +151,33 @@ hv_get_ringbuffer_availbytes(struct hv_ring_buffer_info *rbi,
*read = dsize - *write;
}
static inline u32 hv_get_bytes_to_read(struct hv_ring_buffer_info *rbi)
{
u32 read_loc, write_loc, dsize, read;
dsize = rbi->ring_datasize;
read_loc = rbi->ring_buffer->read_index;
write_loc = READ_ONCE(rbi->ring_buffer->write_index);
read = write_loc >= read_loc ? (write_loc - read_loc) :
(dsize - read_loc) + write_loc;
return read;
}
static inline u32 hv_get_bytes_to_write(struct hv_ring_buffer_info *rbi)
{
u32 read_loc, write_loc, dsize, write;
dsize = rbi->ring_datasize;
read_loc = READ_ONCE(rbi->ring_buffer->read_index);
write_loc = rbi->ring_buffer->write_index;
write = write_loc >= read_loc ? dsize - (write_loc - read_loc) :
read_loc - write_loc;
return write;
}
/*
* VMBUS version is 32 bit entity broken up into
* two 16 bit quantities: major_number. minor_number.