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/*
* Copyright (c) 2006 Oracle. All rights reserved.
*
* This software is available to you under a choice of one of two
* licenses. You may choose to be licensed under the terms of the GNU
* General Public License (GPL) Version 2, available from the file
* COPYING in the main directory of this source tree, or the
* OpenIB.org BSD license below:
*
* Redistribution and use in source and binary forms, with or
* without modification, are permitted provided that the following
* conditions are met:
*
* - Redistributions of source code must retain the above
* copyright notice, this list of conditions and the following
* disclaimer.
*
* - Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials
* provided with the distribution.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*
*/
#include <linux/highmem.h>
#include <linux/gfp.h>
#include <linux/cpu.h>
#include <linux/export.h>
#include "rds.h"
struct rds_page_remainder {
struct page *r_page;
unsigned long r_offset;
};
static DEFINE_PER_CPU_SHARED_ALIGNED(struct rds_page_remainder,
rds_page_remainders);
/*
* returns 0 on success or -errno on failure.
*
* We don't have to worry about flush_dcache_page() as this only works
* with private pages. If, say, we were to do directed receive to pinned
* user pages we'd have to worry more about cache coherence. (Though
* the flush_dcache_page() in get_user_pages() would probably be enough).
*/
int rds_page_copy_user(struct page *page, unsigned long offset,
void __user *ptr, unsigned long bytes,
int to_user)
{
unsigned long ret;
void *addr;
addr = kmap(page);
if (to_user) {
rds_stats_add(s_copy_to_user, bytes);
ret = copy_to_user(ptr, addr + offset, bytes);
} else {
rds_stats_add(s_copy_from_user, bytes);
ret = copy_from_user(addr + offset, ptr, bytes);
}
kunmap(page);
return ret ? -EFAULT : 0;
}
EXPORT_SYMBOL_GPL(rds_page_copy_user);
/**
* rds_page_remainder_alloc - build up regions of a message.
*
* @scat: Scatter list for message
* @bytes: the number of bytes needed.
* @gfp: the waiting behaviour of the allocation
*
* @gfp is always ored with __GFP_HIGHMEM. Callers must be prepared to
* kmap the pages, etc.
*
* If @bytes is at least a full page then this just returns a page from
* alloc_page().
*
* If @bytes is a partial page then this stores the unused region of the
* page in a per-cpu structure. Future partial-page allocations may be
* satisfied from that cached region. This lets us waste less memory on
* small allocations with minimal complexity. It works because the transmit
* path passes read-only page regions down to devices. They hold a page
* reference until they are done with the region.
*/
int rds_page_remainder_alloc(struct scatterlist *scat, unsigned long bytes,
gfp_t gfp)
{
struct rds_page_remainder *rem;
unsigned long flags;
struct page *page;
int ret;
gfp |= __GFP_HIGHMEM;
/* jump straight to allocation if we're trying for a huge page */
if (bytes >= PAGE_SIZE) {
page = alloc_page(gfp);
if (!page) {
ret = -ENOMEM;
} else {
sg_set_page(scat, page, PAGE_SIZE, 0);
ret = 0;
}
goto out;
}
rem = &per_cpu(rds_page_remainders, get_cpu());
local_irq_save(flags);
while (1) {
/* avoid a tiny region getting stuck by tossing it */
if (rem->r_page && bytes > (PAGE_SIZE - rem->r_offset)) {
rds_stats_inc(s_page_remainder_miss);
__free_page(rem->r_page);
rem->r_page = NULL;
}
/* hand out a fragment from the cached page */
if (rem->r_page && bytes <= (PAGE_SIZE - rem->r_offset)) {
sg_set_page(scat, rem->r_page, bytes, rem->r_offset);
get_page(sg_page(scat));
if (rem->r_offset != 0)
rds_stats_inc(s_page_remainder_hit);
rem->r_offset += bytes;
if (rem->r_offset == PAGE_SIZE) {
__free_page(rem->r_page);
rem->r_page = NULL;
}
ret = 0;
break;
}
/* alloc if there is nothing for us to use */
local_irq_restore(flags);
put_cpu();
page = alloc_page(gfp);
rem = &per_cpu(rds_page_remainders, get_cpu());
local_irq_save(flags);
if (!page) {
ret = -ENOMEM;
break;
}
/* did someone race to fill the remainder before us? */
if (rem->r_page) {
__free_page(page);
continue;
}
/* otherwise install our page and loop around to alloc */
rem->r_page = page;
rem->r_offset = 0;
}
local_irq_restore(flags);
put_cpu();
out:
rdsdebug("bytes %lu ret %d %p %u %u\n", bytes, ret,
ret ? NULL : sg_page(scat), ret ? 0 : scat->offset,
ret ? 0 : scat->length);
return ret;
}
EXPORT_SYMBOL_GPL(rds_page_remainder_alloc);
void rds_page_exit(void)
{
unsigned int cpu;
for_each_possible_cpu(cpu) {
struct rds_page_remainder *rem;
rem = &per_cpu(rds_page_remainders, cpu);
rdsdebug("cpu %u\n", cpu);
if (rem->r_page)
__free_page(rem->r_page);
rem->r_page = NULL;
}
}
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