From a6341f000024cdf1ec14dc26743a409a17378db5 Mon Sep 17 00:00:00 2001 From: "K. Y. Srinivasan" Date: Sat, 2 Apr 2016 17:59:46 -0700 Subject: [PATCH] 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 --- drivers/hv/ring_buffer.c | 25 ++++--------------------- include/linux/hyperv.h | 27 +++++++++++++++++++++++++++ 2 files changed, 31 insertions(+), 21 deletions(-) diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c index a40a73a7b71d..544362c6a9ca 100644 --- a/drivers/hv/ring_buffer.c +++ b/drivers/hv/ring_buffer.c @@ -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)) { /* 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. -- 2.39.5