IB/uverbs: Export ib_umem_get()/ib_umem_release() to modules
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>
diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c
new file mode 100644
index 0000000..48e854c
--- /dev/null
+++ b/drivers/infiniband/core/umem.c
@@ -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(¤t->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(¤t->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);
