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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 <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
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

25
drivers/hv/ring_buffer.c
View File

@ -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)) {
/*

27
include/linux/hyperv.h
View File

@ -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.