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Commit a6341f00 authored by K. Y. Srinivasan's avatar K. Y. Srinivasan Committed by Greg Kroah-Hartman
Browse files

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: default avatarK. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent a389fcfd

drivers/hv/ring_buffer.c

+4 −21
Original line number Diff line number Diff line
@@ -38,8 +38,6 @@ void hv_begin_read(struct hv_ring_buffer_info *rbi) 


u32 hv_end_read(struct hv_ring_buffer_info *rbi)

{

	u32 read;

	u32 write;



	rbi->ring_buffer->interrupt_mask = 0;

	mb();
@@ -49,9 +47,7 @@ u32 hv_end_read(struct hv_ring_buffer_info *rbi) 
	 * If it is not, we raced and we need to process new

	 * incoming messages.

	 */

	hv_get_ringbuffer_availbytes(rbi, &read, &write);



	return read;

	return hv_get_bytes_to_read(rbi);

}



/*
@@ -106,9 +102,6 @@ static bool hv_need_to_signal(u32 old_write, struct hv_ring_buffer_info *rbi) 
static bool hv_need_to_signal_on_read(struct hv_ring_buffer_info *rbi)

{

	u32 cur_write_sz;

	u32 r_size;

	u32 write_loc;

	u32 read_loc = rbi->ring_buffer->read_index;

	u32 pending_sz;



	/*
@@ -125,14 +118,11 @@ static bool hv_need_to_signal_on_read(struct hv_ring_buffer_info *rbi) 
	mb();



	pending_sz = rbi->ring_buffer->pending_send_sz;

	write_loc = rbi->ring_buffer->write_index;

	/* If the other end is not blocked on write don't bother. */

	if (pending_sz == 0)

		return false;



	r_size = rbi->ring_datasize;

	cur_write_sz = write_loc >= read_loc ? r_size - (write_loc - read_loc) :

			read_loc - write_loc;

	cur_write_sz = hv_get_bytes_to_write(rbi);



	if (cur_write_sz >= pending_sz)

		return true;
@@ -332,7 +322,6 @@ int hv_ringbuffer_write(struct hv_ring_buffer_info *outring_info, 
{

	int i = 0;

	u32 bytes_avail_towrite;

	u32 bytes_avail_toread;

	u32 totalbytes_towrite = 0;



	u32 next_write_location;
@@ -348,9 +337,7 @@ int hv_ringbuffer_write(struct hv_ring_buffer_info *outring_info, 
	if (lock)

		spin_lock_irqsave(&outring_info->ring_lock, flags);



	hv_get_ringbuffer_availbytes(outring_info,

				&bytes_avail_toread,

				&bytes_avail_towrite);

	bytes_avail_towrite = hv_get_bytes_to_write(outring_info);



	/*

	 * If there is only room for the packet, assume it is full.
@@ -401,7 +388,6 @@ int hv_ringbuffer_read(struct hv_ring_buffer_info *inring_info, 
		       void *buffer, u32 buflen, u32 *buffer_actual_len,

		       u64 *requestid, bool *signal, bool raw)

{

	u32 bytes_avail_towrite;

	u32 bytes_avail_toread;

	u32 next_read_location = 0;

	u64 prev_indices = 0;
@@ -417,10 +403,7 @@ int hv_ringbuffer_read(struct hv_ring_buffer_info *inring_info, 
	*buffer_actual_len = 0;

	*requestid = 0;



	hv_get_ringbuffer_availbytes(inring_info,

				&bytes_avail_toread,

				&bytes_avail_towrite);



	bytes_avail_toread = hv_get_bytes_to_read(inring_info);

	/* Make sure there is something to read */

	if (bytes_avail_toread < sizeof(desc)) {

		/*

include/linux/hyperv.h

+27 −0
Original line number Diff line number Diff line
@@ -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.