2009-07-13 17:02:34 -06:00
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/*
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*
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* Copyright (c) 2009, Microsoft Corporation.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License along with
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* this program; if not, write to the Free Software Foundation, Inc., 59 Temple
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* Place - Suite 330, Boston, MA 02111-1307 USA.
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*
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* Authors:
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* Haiyang Zhang <haiyangz@microsoft.com>
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* Hank Janssen <hjanssen@microsoft.com>
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2011-05-10 08:55:30 -06:00
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* K. Y. Srinivasan <kys@microsoft.com>
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2009-07-13 17:02:34 -06:00
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*
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*/
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2011-03-29 14:58:47 -06:00
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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2009-07-13 17:02:34 -06:00
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2009-08-17 18:22:08 -06:00
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#include <linux/kernel.h>
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#include <linux/mm.h>
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2011-10-04 13:29:52 -06:00
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#include <linux/hyperv.h>
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2011-05-12 20:34:15 -06:00
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2011-05-12 20:34:28 -06:00
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#include "hyperv_vmbus.h"
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2009-07-13 17:02:34 -06:00
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2012-12-01 07:46:32 -07:00
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void hv_begin_read(struct hv_ring_buffer_info *rbi)
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{
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rbi->ring_buffer->interrupt_mask = 1;
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smp_mb();
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}
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u32 hv_end_read(struct hv_ring_buffer_info *rbi)
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{
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u32 read;
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u32 write;
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rbi->ring_buffer->interrupt_mask = 0;
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smp_mb();
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/*
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* Now check to see if the ring buffer is still empty.
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* If it is not, we raced and we need to process new
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* incoming messages.
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*/
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hv_get_ringbuffer_availbytes(rbi, &read, &write);
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return read;
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}
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2012-12-01 07:46:36 -07:00
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/*
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* When we write to the ring buffer, check if the host needs to
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* be signaled. Here is the details of this protocol:
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*
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* 1. The host guarantees that while it is draining the
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* ring buffer, it will set the interrupt_mask to
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* indicate it does not need to be interrupted when
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* new data is placed.
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*
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* 2. The host guarantees that it will completely drain
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* the ring buffer before exiting the read loop. Further,
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* once the ring buffer is empty, it will clear the
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* interrupt_mask and re-check to see if new data has
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* arrived.
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*/
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static bool hv_need_to_signal(u32 old_write, struct hv_ring_buffer_info *rbi)
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{
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2013-03-29 15:30:38 -06:00
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smp_mb();
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2012-12-01 07:46:36 -07:00
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if (rbi->ring_buffer->interrupt_mask)
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return false;
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/*
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* This is the only case we need to signal when the
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* ring transitions from being empty to non-empty.
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*/
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if (old_write == rbi->ring_buffer->read_index)
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return true;
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return false;
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}
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2012-12-01 07:46:57 -07:00
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/*
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* To optimize the flow management on the send-side,
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* when the sender is blocked because of lack of
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* sufficient space in the ring buffer, potential the
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* consumer of the ring buffer can signal the producer.
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* This is controlled by the following parameters:
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*
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* 1. pending_send_sz: This is the size in bytes that the
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* producer is trying to send.
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* 2. The feature bit feat_pending_send_sz set to indicate if
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* the consumer of the ring will signal when the ring
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* state transitions from being full to a state where
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* there is room for the producer to send the pending packet.
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*/
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static bool hv_need_to_signal_on_read(u32 old_rd,
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struct hv_ring_buffer_info *rbi)
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{
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u32 prev_write_sz;
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u32 cur_write_sz;
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u32 r_size;
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u32 write_loc = rbi->ring_buffer->write_index;
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u32 read_loc = rbi->ring_buffer->read_index;
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u32 pending_sz = rbi->ring_buffer->pending_send_sz;
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/*
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* If the other end is not blocked on write don't bother.
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*/
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if (pending_sz == 0)
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return false;
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r_size = rbi->ring_datasize;
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cur_write_sz = write_loc >= read_loc ? r_size - (write_loc - read_loc) :
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read_loc - write_loc;
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prev_write_sz = write_loc >= old_rd ? r_size - (write_loc - old_rd) :
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old_rd - write_loc;
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if ((prev_write_sz < pending_sz) && (cur_write_sz >= pending_sz))
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return true;
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return false;
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}
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2009-07-13 17:02:34 -06:00
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2011-05-10 08:55:30 -06:00
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/*
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* hv_get_next_write_location()
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*
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* Get the next write location for the specified ring buffer
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*
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*/
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2009-07-14 16:09:36 -06:00
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static inline u32
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2011-05-10 08:55:29 -06:00
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hv_get_next_write_location(struct hv_ring_buffer_info *ring_info)
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2009-07-13 17:02:34 -06:00
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{
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2010-11-08 15:04:46 -07:00
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u32 next = ring_info->ring_buffer->write_index;
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2009-07-13 17:02:34 -06:00
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return next;
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}
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2011-05-10 08:55:30 -06:00
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/*
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* hv_set_next_write_location()
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*
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* Set the next write location for the specified ring buffer
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*
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*/
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2009-07-13 17:02:34 -06:00
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static inline void
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2011-05-10 08:55:29 -06:00
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hv_set_next_write_location(struct hv_ring_buffer_info *ring_info,
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2010-11-08 15:04:46 -07:00
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u32 next_write_location)
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2009-07-13 17:02:34 -06:00
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{
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2010-11-08 15:04:46 -07:00
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ring_info->ring_buffer->write_index = next_write_location;
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2009-07-13 17:02:34 -06:00
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}
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2011-05-10 08:55:30 -06:00
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/*
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* hv_get_next_read_location()
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*
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* Get the next read location for the specified ring buffer
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*/
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2009-07-14 16:09:36 -06:00
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static inline u32
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2011-05-10 08:55:29 -06:00
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hv_get_next_read_location(struct hv_ring_buffer_info *ring_info)
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2009-07-13 17:02:34 -06:00
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{
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2010-11-08 15:04:46 -07:00
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u32 next = ring_info->ring_buffer->read_index;
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2009-07-13 17:02:34 -06:00
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return next;
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}
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2011-05-10 08:55:30 -06:00
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/*
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* hv_get_next_readlocation_withoffset()
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*
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* Get the next read location + offset for the specified ring buffer.
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* This allows the caller to skip
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*/
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2009-07-14 16:09:36 -06:00
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static inline u32
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2011-05-10 08:55:29 -06:00
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hv_get_next_readlocation_withoffset(struct hv_ring_buffer_info *ring_info,
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2010-11-08 15:04:47 -07:00
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u32 offset)
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2009-07-13 17:02:34 -06:00
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{
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2010-11-08 15:04:46 -07:00
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u32 next = ring_info->ring_buffer->read_index;
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2009-07-13 17:02:34 -06:00
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2010-11-08 15:04:46 -07:00
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next += offset;
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next %= ring_info->ring_datasize;
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2009-07-13 17:02:34 -06:00
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return next;
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}
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2011-05-10 08:55:30 -06:00
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/*
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*
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* hv_set_next_read_location()
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*
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* Set the next read location for the specified ring buffer
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*
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*/
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2009-07-13 17:02:34 -06:00
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static inline void
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2011-05-10 08:55:29 -06:00
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hv_set_next_read_location(struct hv_ring_buffer_info *ring_info,
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2010-11-08 15:04:46 -07:00
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u32 next_read_location)
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2009-07-13 17:02:34 -06:00
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{
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2010-11-08 15:04:46 -07:00
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ring_info->ring_buffer->read_index = next_read_location;
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2009-07-13 17:02:34 -06:00
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}
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2011-05-10 08:55:30 -06:00
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/*
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*
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* hv_get_ring_buffer()
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*
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* Get the start of the ring buffer
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*/
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2009-07-14 16:06:28 -06:00
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static inline void *
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2011-05-10 08:55:29 -06:00
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hv_get_ring_buffer(struct hv_ring_buffer_info *ring_info)
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2009-07-13 17:02:34 -06:00
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{
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2010-11-08 15:04:46 -07:00
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return (void *)ring_info->ring_buffer->buffer;
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2009-07-13 17:02:34 -06:00
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}
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2011-05-10 08:55:30 -06:00
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/*
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*
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* hv_get_ring_buffersize()
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*
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* Get the size of the ring buffer
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*/
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2009-07-14 16:09:36 -06:00
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static inline u32
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2011-05-10 08:55:29 -06:00
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hv_get_ring_buffersize(struct hv_ring_buffer_info *ring_info)
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2009-07-13 17:02:34 -06:00
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{
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2010-11-08 15:04:46 -07:00
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return ring_info->ring_datasize;
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2009-07-13 17:02:34 -06:00
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}
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2011-05-10 08:55:30 -06:00
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/*
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*
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* hv_get_ring_bufferindices()
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*
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* Get the read and write indices as u64 of the specified ring buffer
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*
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*/
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2009-07-14 16:10:26 -06:00
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static inline u64
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2011-05-10 08:55:29 -06:00
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hv_get_ring_bufferindices(struct hv_ring_buffer_info *ring_info)
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2009-07-13 17:02:34 -06:00
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{
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2010-11-08 15:04:46 -07:00
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return (u64)ring_info->ring_buffer->write_index << 32;
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2009-07-13 17:02:34 -06:00
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}
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2011-05-10 08:55:31 -06:00
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/*
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*
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* hv_copyfrom_ringbuffer()
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*
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* Helper routine to copy to source from ring buffer.
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* Assume there is enough room. Handles wrap-around in src case only!!
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*
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*/
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static u32 hv_copyfrom_ringbuffer(
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struct hv_ring_buffer_info *ring_info,
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void *dest,
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u32 destlen,
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u32 start_read_offset)
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{
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void *ring_buffer = hv_get_ring_buffer(ring_info);
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u32 ring_buffer_size = hv_get_ring_buffersize(ring_info);
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u32 frag_len;
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/* wrap-around detected at the src */
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if (destlen > ring_buffer_size - start_read_offset) {
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frag_len = ring_buffer_size - start_read_offset;
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memcpy(dest, ring_buffer + start_read_offset, frag_len);
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memcpy(dest + frag_len, ring_buffer, destlen - frag_len);
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} else
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memcpy(dest, ring_buffer + start_read_offset, destlen);
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start_read_offset += destlen;
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start_read_offset %= ring_buffer_size;
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return start_read_offset;
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}
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2011-05-10 08:55:32 -06:00
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/*
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*
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* hv_copyto_ringbuffer()
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*
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* Helper routine to copy from source to ring buffer.
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* Assume there is enough room. Handles wrap-around in dest case only!!
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*
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*/
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static u32 hv_copyto_ringbuffer(
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2010-11-08 15:04:46 -07:00
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struct hv_ring_buffer_info *ring_info,
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u32 start_write_offset,
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void *src,
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2011-05-10 08:55:32 -06:00
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u32 srclen)
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{
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void *ring_buffer = hv_get_ring_buffer(ring_info);
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u32 ring_buffer_size = hv_get_ring_buffersize(ring_info);
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u32 frag_len;
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/* wrap-around detected! */
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if (srclen > ring_buffer_size - start_write_offset) {
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frag_len = ring_buffer_size - start_write_offset;
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memcpy(ring_buffer + start_write_offset, src, frag_len);
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memcpy(ring_buffer, src + frag_len, srclen - frag_len);
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} else
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memcpy(ring_buffer + start_write_offset, src, srclen);
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2009-07-13 17:02:34 -06:00
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2011-05-10 08:55:32 -06:00
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start_write_offset += srclen;
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start_write_offset %= ring_buffer_size;
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return start_write_offset;
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}
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2009-07-13 17:02:34 -06:00
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2011-05-10 08:55:30 -06:00
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/*
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*
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* hv_ringbuffer_get_debuginfo()
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*
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* Get various debug metrics for the specified ring buffer
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*
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*/
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2011-05-10 08:55:28 -06:00
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void hv_ringbuffer_get_debuginfo(struct hv_ring_buffer_info *ring_info,
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2010-07-27 12:37:32 -06:00
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struct hv_ring_buffer_debug_info *debug_info)
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2009-07-13 17:02:34 -06:00
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{
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2010-11-08 15:04:46 -07:00
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u32 bytes_avail_towrite;
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u32 bytes_avail_toread;
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2009-07-13 17:02:34 -06:00
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2010-11-08 15:04:46 -07:00
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if (ring_info->ring_buffer) {
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2011-05-10 08:55:29 -06:00
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hv_get_ringbuffer_availbytes(ring_info,
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2010-11-08 15:04:46 -07:00
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&bytes_avail_toread,
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&bytes_avail_towrite);
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2009-07-13 17:02:34 -06:00
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|
|
2010-11-08 15:04:46 -07:00
|
|
|
debug_info->bytes_avail_toread = bytes_avail_toread;
|
|
|
|
debug_info->bytes_avail_towrite = bytes_avail_towrite;
|
2010-11-08 15:04:45 -07:00
|
|
|
debug_info->current_read_index =
|
2010-11-08 15:04:46 -07:00
|
|
|
ring_info->ring_buffer->read_index;
|
2010-11-08 15:04:45 -07:00
|
|
|
debug_info->current_write_index =
|
2010-11-08 15:04:46 -07:00
|
|
|
ring_info->ring_buffer->write_index;
|
2010-11-08 15:04:45 -07:00
|
|
|
debug_info->current_interrupt_mask =
|
2010-11-08 15:04:46 -07:00
|
|
|
ring_info->ring_buffer->interrupt_mask;
|
2009-07-13 17:02:34 -06:00
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2011-05-10 08:55:30 -06:00
|
|
|
/*
|
|
|
|
*
|
|
|
|
* hv_ringbuffer_init()
|
|
|
|
*
|
|
|
|
*Initialize the ring buffer
|
|
|
|
*
|
|
|
|
*/
|
2011-05-10 08:55:21 -06:00
|
|
|
int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info,
|
2010-11-08 15:04:46 -07:00
|
|
|
void *buffer, u32 buflen)
|
2009-07-13 17:02:34 -06:00
|
|
|
{
|
2010-07-27 12:47:08 -06:00
|
|
|
if (sizeof(struct hv_ring_buffer) != PAGE_SIZE)
|
2010-05-05 13:27:49 -06:00
|
|
|
return -EINVAL;
|
2009-07-13 17:02:34 -06:00
|
|
|
|
2010-11-08 15:04:46 -07:00
|
|
|
memset(ring_info, 0, sizeof(struct hv_ring_buffer_info));
|
2009-07-13 17:02:34 -06:00
|
|
|
|
2010-11-08 15:04:46 -07:00
|
|
|
ring_info->ring_buffer = (struct hv_ring_buffer *)buffer;
|
|
|
|
ring_info->ring_buffer->read_index =
|
|
|
|
ring_info->ring_buffer->write_index = 0;
|
2009-07-13 17:02:34 -06:00
|
|
|
|
2010-11-08 15:04:46 -07:00
|
|
|
ring_info->ring_size = buflen;
|
|
|
|
ring_info->ring_datasize = buflen - sizeof(struct hv_ring_buffer);
|
2009-07-13 17:02:34 -06:00
|
|
|
|
2010-11-08 15:04:46 -07:00
|
|
|
spin_lock_init(&ring_info->ring_lock);
|
2009-07-13 17:02:34 -06:00
|
|
|
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
2011-05-10 08:55:30 -06:00
|
|
|
/*
|
|
|
|
*
|
|
|
|
* hv_ringbuffer_cleanup()
|
|
|
|
*
|
|
|
|
* Cleanup the ring buffer
|
|
|
|
*
|
|
|
|
*/
|
2011-05-10 08:55:22 -06:00
|
|
|
void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info)
|
2009-07-13 17:02:34 -06:00
|
|
|
{
|
|
|
|
}
|
|
|
|
|
2011-05-10 08:55:30 -06:00
|
|
|
/*
|
|
|
|
*
|
|
|
|
* hv_ringbuffer_write()
|
|
|
|
*
|
|
|
|
* Write to the ring buffer
|
|
|
|
*
|
|
|
|
*/
|
2011-05-10 08:55:23 -06:00
|
|
|
int hv_ringbuffer_write(struct hv_ring_buffer_info *outring_info,
|
2012-12-01 07:46:36 -07:00
|
|
|
struct scatterlist *sglist, u32 sgcount, bool *signal)
|
2009-07-13 17:02:34 -06:00
|
|
|
{
|
2010-02-03 08:34:27 -07:00
|
|
|
int i = 0;
|
2010-11-08 15:04:46 -07:00
|
|
|
u32 bytes_avail_towrite;
|
|
|
|
u32 bytes_avail_toread;
|
|
|
|
u32 totalbytes_towrite = 0;
|
2009-07-13 17:02:34 -06:00
|
|
|
|
2009-07-30 09:37:23 -06:00
|
|
|
struct scatterlist *sg;
|
2011-05-10 08:55:33 -06:00
|
|
|
u32 next_write_location;
|
2012-12-01 07:46:36 -07:00
|
|
|
u32 old_write;
|
2010-11-08 15:04:46 -07:00
|
|
|
u64 prev_indices = 0;
|
2009-07-15 15:55:14 -06:00
|
|
|
unsigned long flags;
|
2009-07-13 17:02:34 -06:00
|
|
|
|
2009-07-30 09:37:23 -06:00
|
|
|
for_each_sg(sglist, sg, sgcount, i)
|
2009-07-13 17:02:34 -06:00
|
|
|
{
|
2010-11-08 15:04:46 -07:00
|
|
|
totalbytes_towrite += sg->length;
|
2009-07-13 17:02:34 -06:00
|
|
|
}
|
|
|
|
|
2010-11-08 15:04:46 -07:00
|
|
|
totalbytes_towrite += sizeof(u64);
|
2009-07-13 17:02:34 -06:00
|
|
|
|
2010-11-08 15:04:46 -07:00
|
|
|
spin_lock_irqsave(&outring_info->ring_lock, flags);
|
2009-07-13 17:02:34 -06:00
|
|
|
|
2011-05-10 08:55:29 -06:00
|
|
|
hv_get_ringbuffer_availbytes(outring_info,
|
2010-11-08 15:04:46 -07:00
|
|
|
&bytes_avail_toread,
|
|
|
|
&bytes_avail_towrite);
|
2009-07-13 17:02:34 -06:00
|
|
|
|
|
|
|
|
2010-02-03 08:34:27 -07:00
|
|
|
/* If there is only room for the packet, assume it is full. */
|
|
|
|
/* Otherwise, the next time around, we think the ring buffer */
|
2009-07-27 14:47:24 -06:00
|
|
|
/* is empty since the read index == write index */
|
2010-11-08 15:04:46 -07:00
|
|
|
if (bytes_avail_towrite <= totalbytes_towrite) {
|
|
|
|
spin_unlock_irqrestore(&outring_info->ring_lock, flags);
|
2011-08-25 10:48:58 -06:00
|
|
|
return -EAGAIN;
|
2009-07-13 17:02:34 -06:00
|
|
|
}
|
|
|
|
|
2009-07-27 14:47:24 -06:00
|
|
|
/* Write to the ring buffer */
|
2011-05-10 08:55:29 -06:00
|
|
|
next_write_location = hv_get_next_write_location(outring_info);
|
2009-07-13 17:02:34 -06:00
|
|
|
|
2012-12-01 07:46:36 -07:00
|
|
|
old_write = next_write_location;
|
|
|
|
|
2009-07-30 09:37:23 -06:00
|
|
|
for_each_sg(sglist, sg, sgcount, i)
|
2009-07-13 17:02:34 -06:00
|
|
|
{
|
2011-05-10 08:55:29 -06:00
|
|
|
next_write_location = hv_copyto_ringbuffer(outring_info,
|
2010-11-08 15:04:46 -07:00
|
|
|
next_write_location,
|
2009-07-30 09:37:23 -06:00
|
|
|
sg_virt(sg),
|
|
|
|
sg->length);
|
2009-07-13 17:02:34 -06:00
|
|
|
}
|
|
|
|
|
2009-07-27 14:47:24 -06:00
|
|
|
/* Set previous packet start */
|
2011-05-10 08:55:29 -06:00
|
|
|
prev_indices = hv_get_ring_bufferindices(outring_info);
|
2009-07-13 17:02:34 -06:00
|
|
|
|
2011-05-10 08:55:29 -06:00
|
|
|
next_write_location = hv_copyto_ringbuffer(outring_info,
|
2010-11-08 15:04:46 -07:00
|
|
|
next_write_location,
|
|
|
|
&prev_indices,
|
2009-07-30 09:37:23 -06:00
|
|
|
sizeof(u64));
|
2009-07-13 17:02:34 -06:00
|
|
|
|
2012-12-01 07:46:36 -07:00
|
|
|
/* Issue a full memory barrier before updating the write index */
|
|
|
|
smp_mb();
|
2009-07-13 17:02:34 -06:00
|
|
|
|
2009-07-27 14:47:24 -06:00
|
|
|
/* Now, update the write location */
|
2011-05-10 08:55:29 -06:00
|
|
|
hv_set_next_write_location(outring_info, next_write_location);
|
2009-07-13 17:02:34 -06:00
|
|
|
|
|
|
|
|
2010-11-08 15:04:46 -07:00
|
|
|
spin_unlock_irqrestore(&outring_info->ring_lock, flags);
|
2012-12-01 07:46:36 -07:00
|
|
|
|
|
|
|
*signal = hv_need_to_signal(old_write, outring_info);
|
2009-07-13 17:02:34 -06:00
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
|
2011-05-10 08:55:30 -06:00
|
|
|
/*
|
|
|
|
*
|
|
|
|
* hv_ringbuffer_peek()
|
|
|
|
*
|
|
|
|
* Read without advancing the read index
|
|
|
|
*
|
|
|
|
*/
|
2011-05-10 08:55:24 -06:00
|
|
|
int hv_ringbuffer_peek(struct hv_ring_buffer_info *Inring_info,
|
2010-11-08 15:04:46 -07:00
|
|
|
void *Buffer, u32 buflen)
|
2009-07-13 17:02:34 -06:00
|
|
|
{
|
2010-11-08 15:04:46 -07:00
|
|
|
u32 bytes_avail_towrite;
|
|
|
|
u32 bytes_avail_toread;
|
|
|
|
u32 next_read_location = 0;
|
2009-07-15 15:55:14 -06:00
|
|
|
unsigned long flags;
|
2009-07-13 17:02:34 -06:00
|
|
|
|
2010-11-08 15:04:46 -07:00
|
|
|
spin_lock_irqsave(&Inring_info->ring_lock, flags);
|
2009-07-13 17:02:34 -06:00
|
|
|
|
2011-05-10 08:55:29 -06:00
|
|
|
hv_get_ringbuffer_availbytes(Inring_info,
|
2010-11-08 15:04:46 -07:00
|
|
|
&bytes_avail_toread,
|
|
|
|
&bytes_avail_towrite);
|
2009-07-13 17:02:34 -06:00
|
|
|
|
2009-07-27 14:47:24 -06:00
|
|
|
/* Make sure there is something to read */
|
2010-11-08 15:04:46 -07:00
|
|
|
if (bytes_avail_toread < buflen) {
|
2009-07-13 17:02:34 -06:00
|
|
|
|
2010-11-08 15:04:46 -07:00
|
|
|
spin_unlock_irqrestore(&Inring_info->ring_lock, flags);
|
2009-07-13 17:02:34 -06:00
|
|
|
|
2011-08-25 10:48:58 -06:00
|
|
|
return -EAGAIN;
|
2009-07-13 17:02:34 -06:00
|
|
|
}
|
|
|
|
|
2009-07-27 14:47:24 -06:00
|
|
|
/* Convert to byte offset */
|
2011-05-10 08:55:29 -06:00
|
|
|
next_read_location = hv_get_next_read_location(Inring_info);
|
2009-07-13 17:02:34 -06:00
|
|
|
|
2011-05-10 08:55:29 -06:00
|
|
|
next_read_location = hv_copyfrom_ringbuffer(Inring_info,
|
2010-02-03 08:34:27 -07:00
|
|
|
Buffer,
|
2010-11-08 15:04:46 -07:00
|
|
|
buflen,
|
|
|
|
next_read_location);
|
2009-07-13 17:02:34 -06:00
|
|
|
|
2010-11-08 15:04:46 -07:00
|
|
|
spin_unlock_irqrestore(&Inring_info->ring_lock, flags);
|
2009-07-13 17:02:34 -06:00
|
|
|
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
|
2011-05-10 08:55:30 -06:00
|
|
|
/*
|
|
|
|
*
|
|
|
|
* hv_ringbuffer_read()
|
|
|
|
*
|
|
|
|
* Read and advance the read index
|
|
|
|
*
|
|
|
|
*/
|
2011-05-10 08:55:25 -06:00
|
|
|
int hv_ringbuffer_read(struct hv_ring_buffer_info *inring_info, void *buffer,
|
2012-12-01 07:46:57 -07:00
|
|
|
u32 buflen, u32 offset, bool *signal)
|
2009-07-13 17:02:34 -06:00
|
|
|
{
|
2010-11-08 15:04:46 -07:00
|
|
|
u32 bytes_avail_towrite;
|
|
|
|
u32 bytes_avail_toread;
|
|
|
|
u32 next_read_location = 0;
|
|
|
|
u64 prev_indices = 0;
|
2009-07-15 15:55:14 -06:00
|
|
|
unsigned long flags;
|
2012-12-01 07:46:57 -07:00
|
|
|
u32 old_read;
|
2009-07-13 17:02:34 -06:00
|
|
|
|
2010-11-08 15:04:46 -07:00
|
|
|
if (buflen <= 0)
|
2010-05-05 13:27:50 -06:00
|
|
|
return -EINVAL;
|
2009-07-13 17:02:34 -06:00
|
|
|
|
2010-11-08 15:04:46 -07:00
|
|
|
spin_lock_irqsave(&inring_info->ring_lock, flags);
|
2009-07-13 17:02:34 -06:00
|
|
|
|
2011-05-10 08:55:29 -06:00
|
|
|
hv_get_ringbuffer_availbytes(inring_info,
|
2010-11-08 15:04:46 -07:00
|
|
|
&bytes_avail_toread,
|
|
|
|
&bytes_avail_towrite);
|
2009-07-13 17:02:34 -06:00
|
|
|
|
2012-12-01 07:46:57 -07:00
|
|
|
old_read = bytes_avail_toread;
|
|
|
|
|
2009-07-27 14:47:24 -06:00
|
|
|
/* Make sure there is something to read */
|
2010-11-08 15:04:46 -07:00
|
|
|
if (bytes_avail_toread < buflen) {
|
|
|
|
spin_unlock_irqrestore(&inring_info->ring_lock, flags);
|
2009-07-13 17:02:34 -06:00
|
|
|
|
2011-08-25 10:48:58 -06:00
|
|
|
return -EAGAIN;
|
2009-07-13 17:02:34 -06:00
|
|
|
}
|
|
|
|
|
2010-11-08 15:04:47 -07:00
|
|
|
next_read_location =
|
2011-05-10 08:55:29 -06:00
|
|
|
hv_get_next_readlocation_withoffset(inring_info, offset);
|
2009-07-13 17:02:34 -06:00
|
|
|
|
2011-05-10 08:55:29 -06:00
|
|
|
next_read_location = hv_copyfrom_ringbuffer(inring_info,
|
2010-11-08 15:04:46 -07:00
|
|
|
buffer,
|
|
|
|
buflen,
|
|
|
|
next_read_location);
|
2009-07-13 17:02:34 -06:00
|
|
|
|
2011-05-10 08:55:29 -06:00
|
|
|
next_read_location = hv_copyfrom_ringbuffer(inring_info,
|
2010-11-08 15:04:46 -07:00
|
|
|
&prev_indices,
|
2010-02-03 08:34:27 -07:00
|
|
|
sizeof(u64),
|
2010-11-08 15:04:46 -07:00
|
|
|
next_read_location);
|
2009-07-13 17:02:34 -06:00
|
|
|
|
2009-07-27 14:47:24 -06:00
|
|
|
/* Make sure all reads are done before we update the read index since */
|
2010-02-03 08:34:27 -07:00
|
|
|
/* the writer may start writing to the read area once the read index */
|
|
|
|
/*is updated */
|
2011-06-06 16:49:51 -06:00
|
|
|
smp_mb();
|
2009-07-13 17:02:34 -06:00
|
|
|
|
2009-07-27 14:47:24 -06:00
|
|
|
/* Update the read index */
|
2011-05-10 08:55:29 -06:00
|
|
|
hv_set_next_read_location(inring_info, next_read_location);
|
2009-07-13 17:02:34 -06:00
|
|
|
|
2010-11-08 15:04:46 -07:00
|
|
|
spin_unlock_irqrestore(&inring_info->ring_lock, flags);
|
2009-07-13 17:02:34 -06:00
|
|
|
|
2012-12-01 07:46:57 -07:00
|
|
|
*signal = hv_need_to_signal_on_read(old_read, inring_info);
|
|
|
|
|
2009-07-13 17:02:34 -06:00
|
|
|
return 0;
|
|
|
|
}
|