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IB/uverbs: Export ib_umem_get()/ib_umem_release() to modules

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Export ib_umem_get()/ib_umem_release() and put low-level drivers in
control of when to call ib_umem_get() to pin and DMA map userspace,
rather than always calling it in ib_uverbs_reg_mr() before calling the
low-level driver's reg_user_mr method.

Also move these functions to be in the ib_core module instead of
ib_uverbs, so that driver modules using them do not depend on
ib_uverbs.

This has a number of advantages:
 - It is better design from the standpoint of making generic code a
   library that can be used or overridden by device-specific code as
   the details of specific devices dictate.
 - Drivers that do not need to pin userspace memory regions do not
   need to take the performance hit of calling ib_mem_get().  For
   example, although I have not tried to implement it in this patch,
   the ipath driver should be able to avoid pinning memory and just
   use copy_{to,from}_user() to access userspace memory regions.
 - Buffers that need special mapping treatment can be identified by
   the low-level driver.  For example, it may be possible to solve
   some Altix-specific memory ordering issues with mthca CQs in
   userspace by mapping CQ buffers with extra flags.
 - Drivers that need to pin and DMA map userspace memory for things
   other than memory regions can use ib_umem_get() directly, instead
   of hacks using extra parameters to their reg_phys_mr method.  For
   example, the mlx4 driver that is pending being merged needs to pin
   and DMA map QP and CQ buffers, but it does not need to create a
   memory key for these buffers.  So the cleanest solution is for mlx4
   to call ib_umem_get() in the create_qp and create_cq methods.

Signed-off-by: Roland Dreier <rolandd@cisco.com>
This commit is contained in:
Roland Dreier
2007-03-04 16:15:11 -08:00
parent 36f021b579
commit f7c6a7b5d5
20 changed files with 357 additions and 204 deletions
Download Patch File Download Diff File Expand all files Collapse all files

273
drivers/infiniband/core/umem.c Normal file
View File

@@ -0,0 +1,273 @@
/*
* Copyright (c) 2005 Topspin Communications. All rights reserved.
* Copyright (c) 2005 Cisco Systems. All rights reserved.
* Copyright (c) 2005 Mellanox Technologies. 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.
*
* $Id: uverbs_mem.c 2743 2005-06-28 22:27:59Z roland $
*/
#include <linux/mm.h>
#include <linux/dma-mapping.h>
#include "uverbs.h"
struct ib_umem_account_work {
struct work_struct work;
struct mm_struct *mm;
unsigned long diff;
};
static void __ib_umem_release(struct ib_device *dev, struct ib_umem *umem, int dirty)
{
struct ib_umem_chunk *chunk, *tmp;
int i;
list_for_each_entry_safe(chunk, tmp, &umem->chunk_list, list) {
ib_dma_unmap_sg(dev, chunk->page_list,
chunk->nents, DMA_BIDIRECTIONAL);
for (i = 0; i < chunk->nents; ++i) {
if (umem->writable && dirty)
set_page_dirty_lock(chunk->page_list[i].page);
put_page(chunk->page_list[i].page);
}
kfree(chunk);
}
}
/**
* ib_umem_get - Pin and DMA map userspace memory.
* @context: userspace context to pin memory for
* @addr: userspace virtual address to start at
* @size: length of region to pin
* @access: IB_ACCESS_xxx flags for memory being pinned
*/
struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr,
size_t size, int access)
{
struct ib_umem *umem;
struct page **page_list;
struct ib_umem_chunk *chunk;
unsigned long locked;
unsigned long lock_limit;
unsigned long cur_base;
unsigned long npages;
int ret;
int off;
int i;
if (!can_do_mlock())
return ERR_PTR(-EPERM);
umem = kmalloc(sizeof *umem, GFP_KERNEL);
if (!umem)
return ERR_PTR(-ENOMEM);
umem->context = context;
umem->length = size;
umem->offset = addr & ~PAGE_MASK;
umem->page_size = PAGE_SIZE;
/*
* We ask for writable memory if any access flags other than
* "remote read" are set. "Local write" and "remote write"
* obviously require write access. "Remote atomic" can do
* things like fetch and add, which will modify memory, and
* "MW bind" can change permissions by binding a window.
*/
umem->writable = !!(access & ~IB_ACCESS_REMOTE_READ);
INIT_LIST_HEAD(&umem->chunk_list);
page_list = (struct page **) __get_free_page(GFP_KERNEL);
if (!page_list) {
kfree(umem);
return ERR_PTR(-ENOMEM);
}
npages = PAGE_ALIGN(size + umem->offset) >> PAGE_SHIFT;
down_write(&current->mm->mmap_sem);
locked = npages + current->mm->locked_vm;
lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur >> PAGE_SHIFT;
if ((locked > lock_limit) && !capable(CAP_IPC_LOCK)) {
ret = -ENOMEM;
goto out;
}
cur_base = addr & PAGE_MASK;
while (npages) {
ret = get_user_pages(current, current->mm, cur_base,
min_t(int, npages,
PAGE_SIZE / sizeof (struct page *)),
1, !umem->writable, page_list, NULL);
if (ret < 0)
goto out;
cur_base += ret * PAGE_SIZE;
npages -= ret;
off = 0;
while (ret) {
chunk = kmalloc(sizeof *chunk + sizeof (struct scatterlist) *
min_t(int, ret, IB_UMEM_MAX_PAGE_CHUNK),
GFP_KERNEL);
if (!chunk) {
ret = -ENOMEM;
goto out;
}
chunk->nents = min_t(int, ret, IB_UMEM_MAX_PAGE_CHUNK);
for (i = 0; i < chunk->nents; ++i) {
chunk->page_list[i].page = page_list[i + off];
chunk->page_list[i].offset = 0;
chunk->page_list[i].length = PAGE_SIZE;
}
chunk->nmap = ib_dma_map_sg(context->device,
&chunk->page_list[0],
chunk->nents,
DMA_BIDIRECTIONAL);
if (chunk->nmap <= 0) {
for (i = 0; i < chunk->nents; ++i)
put_page(chunk->page_list[i].page);
kfree(chunk);
ret = -ENOMEM;
goto out;
}
ret -= chunk->nents;
off += chunk->nents;
list_add_tail(&chunk->list, &umem->chunk_list);
}
ret = 0;
}
out:
if (ret < 0) {
__ib_umem_release(context->device, umem, 0);
kfree(umem);
} else
current->mm->locked_vm = locked;
up_write(&current->mm->mmap_sem);
free_page((unsigned long) page_list);
return ret < 0 ? ERR_PTR(ret) : umem;
}
EXPORT_SYMBOL(ib_umem_get);
static void ib_umem_account(struct work_struct *_work)
{
struct ib_umem_account_work *work =
container_of(_work, struct ib_umem_account_work, work);
down_write(&work->mm->mmap_sem);
work->mm->locked_vm -= work->diff;
up_write(&work->mm->mmap_sem);
mmput(work->mm);
kfree(work);
}
/**
* ib_umem_release - release memory pinned with ib_umem_get
* @umem: umem struct to release
*/
void ib_umem_release(struct ib_umem *umem)
{
struct ib_umem_account_work *work;
struct ib_ucontext *context = umem->context;
struct mm_struct *mm;
unsigned long diff;
__ib_umem_release(umem->context->device, umem, 1);
mm = get_task_mm(current);
if (!mm)
return;
diff = PAGE_ALIGN(umem->length + umem->offset) >> PAGE_SHIFT;
kfree(umem);
/*
* We may be called with the mm's mmap_sem already held. This
* can happen when a userspace munmap() is the call that drops
* the last reference to our file and calls our release
* method. If there are memory regions to destroy, we'll end
* up here and not be able to take the mmap_sem. In that case
* we defer the vm_locked accounting to the system workqueue.
*/
if (context->closing && !down_write_trylock(&mm->mmap_sem)) {
work = kmalloc(sizeof *work, GFP_KERNEL);
if (!work) {
mmput(mm);
return;
}
INIT_WORK(&work->work, ib_umem_account);
work->mm = mm;
work->diff = diff;
schedule_work(&work->work);
return;
} else
down_write(&mm->mmap_sem);
current->mm->locked_vm -= diff;
up_write(&mm->mmap_sem);
mmput(mm);
}
EXPORT_SYMBOL(ib_umem_release);
int ib_umem_page_count(struct ib_umem *umem)
{
struct ib_umem_chunk *chunk;
int shift;
int i;
int n;
shift = ilog2(umem->page_size);
n = 0;
list_for_each_entry(chunk, &umem->chunk_list, list)
for (i = 0; i < chunk->nmap; ++i)
n += sg_dma_len(&chunk->page_list[i]) >> shift;
return n;
}
EXPORT_SYMBOL(ib_umem_page_count);