linux/include/rdma/ib_fmr_pool.h
Gustavo A. R. Silva 5b361328ca RDMA: Replace zero-length array with flexible-array member
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

Link: https://lore.kernel.org/r/20200213010425.GA13068@embeddedor.com
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com> # added a few more
2020-02-20 13:33:51 -04:00

94 lines
3.4 KiB
C

/*
* Copyright (c) 2004 Topspin Corporation. All rights reserved.
* Copyright (c) 2005 Sun Microsystems, Inc. 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.
*/
#if !defined(IB_FMR_POOL_H)
#define IB_FMR_POOL_H
#include <rdma/ib_verbs.h>
struct ib_fmr_pool;
/**
* struct ib_fmr_pool_param - Parameters for creating FMR pool
* @max_pages_per_fmr:Maximum number of pages per map request.
* @page_shift: Log2 of sizeof "pages" mapped by this fmr
* @access:Access flags for FMRs in pool.
* @pool_size:Number of FMRs to allocate for pool.
* @dirty_watermark:Flush is triggered when @dirty_watermark dirty
* FMRs are present.
* @flush_function:Callback called when unmapped FMRs are flushed and
* more FMRs are possibly available for mapping
* @flush_arg:Context passed to user's flush function.
* @cache:If set, FMRs may be reused after unmapping for identical map
* requests.
*/
struct ib_fmr_pool_param {
int max_pages_per_fmr;
int page_shift;
enum ib_access_flags access;
int pool_size;
int dirty_watermark;
void (*flush_function)(struct ib_fmr_pool *pool,
void *arg);
void *flush_arg;
unsigned cache:1;
};
struct ib_pool_fmr {
struct ib_fmr *fmr;
struct ib_fmr_pool *pool;
struct list_head list;
struct hlist_node cache_node;
int ref_count;
int remap_count;
u64 io_virtual_address;
int page_list_len;
u64 page_list[];
};
struct ib_fmr_pool *ib_create_fmr_pool(struct ib_pd *pd,
struct ib_fmr_pool_param *params);
void ib_destroy_fmr_pool(struct ib_fmr_pool *pool);
int ib_flush_fmr_pool(struct ib_fmr_pool *pool);
struct ib_pool_fmr *ib_fmr_pool_map_phys(struct ib_fmr_pool *pool_handle,
u64 *page_list,
int list_len,
u64 io_virtual_address);
void ib_fmr_pool_unmap(struct ib_pool_fmr *fmr);
#endif /* IB_FMR_POOL_H */