kernel_optimize_test/include/linux/async_tx.h
Dan Williams b802c8410c async_tx: deprecate broken support for channel switching
Back in 2011, Russell pointed out that the "async_tx channel switch"
capability was violating expectations of the dma mapping api [1]. At the
time the existing uses were reviewed as still usable, but that longer
term we needed a rework of the raid offload implementation. While some
of the framework for a fixed implementation was introduced in 2012 [2],
the wider rewrite never materialized.

There continues to be interest in raid offload with new dma/raid engine
drivers being submitted. Those drivers must not build on top of the
broken channel switching capability.

Prevent async_tx from using an offload engine if the channel switching
capability is enabled. This still allows the engine to be used for other
purposes, but the broken way async_tx uses these engines for raid will
be disabled. For configurations where this causes a performance
regression the only solution is to start the work of eliminating the
async_tx api and moving channel management into the raid code directly
where it can manage marshalling an operation stream between multiple dma
channels.

[1]: http://lists.infradead.org/pipermail/linux-arm-kernel/2011-January/036753.html
[2]: https://lkml.org/lkml/2012/12/6/71

Cc: Anatolij Gustschin <agust@denx.de>
Cc: Anup Patel <anup.patel@broadcom.com>
Cc: Rameshwar Prasad Sahu <rsahu@apm.com>
Cc: Saeed Bishara <saeed.bishara@gmail.com>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Reported-by: Russell King <linux@armlinux.org.uk>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
2017-02-16 10:08:41 +05:30

209 lines
6.8 KiB
C

/*
* Copyright © 2006, Intel Corporation.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License along with
* this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
*
*/
#ifndef _ASYNC_TX_H_
#define _ASYNC_TX_H_
#include <linux/dmaengine.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
/* on architectures without dma-mapping capabilities we need to ensure
* that the asynchronous path compiles away
*/
#ifdef CONFIG_HAS_DMA
#define __async_inline
#else
#define __async_inline __always_inline
#endif
/**
* dma_chan_ref - object used to manage dma channels received from the
* dmaengine core.
* @chan - the channel being tracked
* @node - node for the channel to be placed on async_tx_master_list
* @rcu - for list_del_rcu
* @count - number of times this channel is listed in the pool
* (for channels with multiple capabiities)
*/
struct dma_chan_ref {
struct dma_chan *chan;
struct list_head node;
struct rcu_head rcu;
atomic_t count;
};
/**
* async_tx_flags - modifiers for the async_* calls
* @ASYNC_TX_XOR_ZERO_DST: this flag must be used for xor operations where the
* the destination address is not a source. The asynchronous case handles this
* implicitly, the synchronous case needs to zero the destination block.
* @ASYNC_TX_XOR_DROP_DST: this flag must be used if the destination address is
* also one of the source addresses. In the synchronous case the destination
* address is an implied source, whereas the asynchronous case it must be listed
* as a source. The destination address must be the first address in the source
* array.
* @ASYNC_TX_ACK: immediately ack the descriptor, precludes setting up a
* dependency chain
* @ASYNC_TX_FENCE: specify that the next operation in the dependency
* chain uses this operation's result as an input
* @ASYNC_TX_PQ_XOR_DST: do not overwrite the syndrome but XOR it with the
* input data. Required for rmw case.
*/
enum async_tx_flags {
ASYNC_TX_XOR_ZERO_DST = (1 << 0),
ASYNC_TX_XOR_DROP_DST = (1 << 1),
ASYNC_TX_ACK = (1 << 2),
ASYNC_TX_FENCE = (1 << 3),
ASYNC_TX_PQ_XOR_DST = (1 << 4),
};
/**
* struct async_submit_ctl - async_tx submission/completion modifiers
* @flags: submission modifiers
* @depend_tx: parent dependency of the current operation being submitted
* @cb_fn: callback routine to run at operation completion
* @cb_param: parameter for the callback routine
* @scribble: caller provided space for dma/page address conversions
*/
struct async_submit_ctl {
enum async_tx_flags flags;
struct dma_async_tx_descriptor *depend_tx;
dma_async_tx_callback cb_fn;
void *cb_param;
void *scribble;
};
#if defined(CONFIG_DMA_ENGINE) && !defined(CONFIG_ASYNC_TX_CHANNEL_SWITCH)
#define async_tx_issue_pending_all dma_issue_pending_all
/**
* async_tx_issue_pending - send pending descriptor to the hardware channel
* @tx: descriptor handle to retrieve hardware context
*
* Note: any dependent operations will have already been issued by
* async_tx_channel_switch, or (in the case of no channel switch) will
* be already pending on this channel.
*/
static inline void async_tx_issue_pending(struct dma_async_tx_descriptor *tx)
{
if (likely(tx)) {
struct dma_chan *chan = tx->chan;
struct dma_device *dma = chan->device;
dma->device_issue_pending(chan);
}
}
#ifdef CONFIG_ARCH_HAS_ASYNC_TX_FIND_CHANNEL
#include <asm/async_tx.h>
#else
#define async_tx_find_channel(dep, type, dst, dst_count, src, src_count, len) \
__async_tx_find_channel(dep, type)
struct dma_chan *
__async_tx_find_channel(struct async_submit_ctl *submit,
enum dma_transaction_type tx_type);
#endif /* CONFIG_ARCH_HAS_ASYNC_TX_FIND_CHANNEL */
#else
static inline void async_tx_issue_pending_all(void)
{
do { } while (0);
}
static inline void async_tx_issue_pending(struct dma_async_tx_descriptor *tx)
{
do { } while (0);
}
static inline struct dma_chan *
async_tx_find_channel(struct async_submit_ctl *submit,
enum dma_transaction_type tx_type, struct page **dst,
int dst_count, struct page **src, int src_count,
size_t len)
{
return NULL;
}
#endif
/**
* async_tx_sync_epilog - actions to take if an operation is run synchronously
* @cb_fn: function to call when the transaction completes
* @cb_fn_param: parameter to pass to the callback routine
*/
static inline void
async_tx_sync_epilog(struct async_submit_ctl *submit)
{
if (submit->cb_fn)
submit->cb_fn(submit->cb_param);
}
typedef union {
unsigned long addr;
struct page *page;
dma_addr_t dma;
} addr_conv_t;
static inline void
init_async_submit(struct async_submit_ctl *args, enum async_tx_flags flags,
struct dma_async_tx_descriptor *tx,
dma_async_tx_callback cb_fn, void *cb_param,
addr_conv_t *scribble)
{
args->flags = flags;
args->depend_tx = tx;
args->cb_fn = cb_fn;
args->cb_param = cb_param;
args->scribble = scribble;
}
void async_tx_submit(struct dma_chan *chan, struct dma_async_tx_descriptor *tx,
struct async_submit_ctl *submit);
struct dma_async_tx_descriptor *
async_xor(struct page *dest, struct page **src_list, unsigned int offset,
int src_cnt, size_t len, struct async_submit_ctl *submit);
struct dma_async_tx_descriptor *
async_xor_val(struct page *dest, struct page **src_list, unsigned int offset,
int src_cnt, size_t len, enum sum_check_flags *result,
struct async_submit_ctl *submit);
struct dma_async_tx_descriptor *
async_memcpy(struct page *dest, struct page *src, unsigned int dest_offset,
unsigned int src_offset, size_t len,
struct async_submit_ctl *submit);
struct dma_async_tx_descriptor *async_trigger_callback(struct async_submit_ctl *submit);
struct dma_async_tx_descriptor *
async_gen_syndrome(struct page **blocks, unsigned int offset, int src_cnt,
size_t len, struct async_submit_ctl *submit);
struct dma_async_tx_descriptor *
async_syndrome_val(struct page **blocks, unsigned int offset, int src_cnt,
size_t len, enum sum_check_flags *pqres, struct page *spare,
struct async_submit_ctl *submit);
struct dma_async_tx_descriptor *
async_raid6_2data_recov(int src_num, size_t bytes, int faila, int failb,
struct page **ptrs, struct async_submit_ctl *submit);
struct dma_async_tx_descriptor *
async_raid6_datap_recov(int src_num, size_t bytes, int faila,
struct page **ptrs, struct async_submit_ctl *submit);
void async_tx_quiesce(struct dma_async_tx_descriptor **tx);
#endif /* _ASYNC_TX_H_ */