From a6341f000024cdf1ec14dc26743a409a17378db5 Mon Sep 17 00:00:00 2001 From: "K. Y. Srinivasan" Date: Sat, 2 Apr 2016 17:59:46 -0700 Subject: Drivers: hv: vmbus: Introduce functions for estimating room in the ring buffer Introduce separate functions for estimating how much can be read from and written to the ring buffer. Signed-off-by: K. Y. Srinivasan Signed-off-by: Greg Kroah-Hartman --- include/linux/hyperv.h | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) (limited to 'include') diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h index aa0fadce9308..66226ceade37 100644 --- a/include/linux/hyperv.h +++ b/include/linux/hyperv.h @@ -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. -- cgit v1.2.3