LinuxLists.cc - [PATCH] dmaengine: dmatest: Remove use of VLAs

2018-04-09 21:10:06

Subject: [PATCH] dmaengine: dmatest: Remove use of VLAs

There's an ongoing effort to remove VLAs from the kernel
(https://lkml.org/lkml/2018/3/7/621) to eventually turn on -Wvla.
The uses in dmatest are bounded by a check to make sure they fit
in a u8 so use that as an upper bound.

Signed-off-by: Laura Abbott <[email protected]>
---
drivers/dma/dmatest.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/dmatest.c b/drivers/dma/dmatest.c
index 80cc2be6483c..dcf787b173e4 100644
--- a/drivers/dma/dmatest.c
+++ b/drivers/dma/dmatest.c
@@ -556,7 +556,8 @@ static int dmatest_func(void *data)
&& !(params->iterations && total_tests >= params->iterations)) {
struct dma_async_tx_descriptor *tx = NULL;
struct dmaengine_unmap_data *um;
- dma_addr_t srcs[src_cnt];
+ /* total buffer count must fit into u8 */
+ dma_addr_t srcs[255];
dma_addr_t *dsts;
unsigned int src_off, dst_off, len;

@@ -669,7 +670,8 @@ static int dmatest_func(void *data)
srcs, src_cnt,
len, flags);
else if (thread->type == DMA_PQ) {
- dma_addr_t dma_pq[dst_cnt];
+ /* dst_cnt can't be more than u8 */
+ dma_addr_t dma_pq[255];

for (i = 0; i < dst_cnt; i++)
dma_pq[i] = dsts[i] + dst_off;
--
2.14.3

2018-04-09 22:54:10

by Sinan Kaya

[permalink] [raw]

Subject: Re: [PATCH] dmaengine: dmatest: Remove use of VLAs

On 4/9/2018 5:06 PM, Laura Abbott wrote:
> + /* dst_cnt can't be more than u8 */
> + dma_addr_t dma_pq[255];

This is 2k stack space on 64 bit architectures. Isn't that a lot?

--
Sinan Kaya
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.

2018-04-09 23:18:21

by Laura Abbott

[permalink] [raw]

Subject: Re: [PATCH] dmaengine: dmatest: Remove use of VLAs

On 04/09/2018 03:48 PM, Sinan Kaya wrote:
> On 4/9/2018 5:06 PM, Laura Abbott wrote:
>> + /* dst_cnt can't be more than u8 */
>> + dma_addr_t dma_pq[255];
>
> This is 2k stack space on 64 bit architectures. Isn't that a lot?
>

Depends on your definition of 'a lot'. My assumption was that
since this was a test module there would be some willingness
to be a bit more generous. The problem is the array size is
based off of the parameters passed in, although oddly enough
it's based off of the minimum of two variables. If you have
a suggestion for a tighter bound we can use that. Another
option is to just switch to allocating the array with kmalloc.
That might be reasonable here since there's other setup
that happens before the test starts.

Thanks,
Laura

2018-04-09 23:22:58

by Sinan Kaya

[permalink] [raw]

Subject: Re: [PATCH] dmaengine: dmatest: Remove use of VLAs

On 2018-04-09 19:14, Laura Abbott wrote:
> On 04/09/2018 03:48 PM, Sinan Kaya wrote:
>> On 4/9/2018 5:06 PM, Laura Abbott wrote:
>>> + /* dst_cnt can't be more than u8 */
>>> + dma_addr_t dma_pq[255];
>>
>> This is 2k stack space on 64 bit architectures. Isn't that a lot?
>>
>
> Depends on your definition of 'a lot'. My assumption was that
> since this was a test module there would be some willingness
> to be a bit more generous. The problem is the array size is
> based off of the parameters passed in, although oddly enough
> it's based off of the minimum of two variables. If you have
> a suggestion for a tighter bound we can use that. Another
> option is to just switch to allocating the array with kmalloc.
> That might be reasonable here since there's other setup
> that happens before the test starts.

I think allocation is a better choice.

>
> Thanks,
> Laura
>
> --
> To unsubscribe from this list: send the line "unsubscribe dmaengine" in
> the body of a message to [email protected]
> More majordomo info at http://vger.kernel.org/majordomo-info.html

2018-04-10 04:07:57

by kernel test robot

[permalink] [raw]

Subject: Re: [PATCH] dmaengine: dmatest: Remove use of VLAs

Hi Laura,

I love your patch!
[auto build test [also build test [if your patch
url: WARNING on linus/master]
WARNING on v4.16 next-20180409]
is applied to the wrong git tree, please drop us a note to help improve the system]
s://github.com/0day-ci/linux/commits/Laura-Abbott/dmaengine-dmatest-Remove-use-of-VLAs/20180410-094633">https://github.com/0day-ci/linux/commits/Laura-Abbott/dmaengine-dmatest-Remove-use-of-VLAs/20180410-094633
(attached as .config)
(Debian 7.3.0-1) 7.3.0
the attached .config to linux build tree
(new ones prefixed by >>):
Complexity 1 include/linux/kasan-checks.h:kasan_check_write
Complexity 2 arch/x86/include/asm/bitops.h:set_bit
Complexity 1 arch/x86/include/asm/bitops.h:constant_test_bit
Complexity 1 arch/x86/include/asm/bitops.h:variable_test_bit
Complexity 1 arch/x86/include/asm/bitops.h:fls
Complexity 1 include/linux/log2.h:__ilog2_u32
Complexity 3 include/linux/log2.h:is_power_of_2
Complexity 1 include/linux/list.h:INIT_LIST_HEAD
Complexity 1 include/linux/list.h:__list_add_valid
Complexity 1 include/linux/list.h:__list_del_entry_valid
Complexity 2 include/linux/list.h:__list_add
Complexity 1 include/linux/list.h:list_add_tail
Complexity 1 include/linux/list.h:__list_del
Complexity 2 include/linux/list.h:__list_del_entry
Complexity 1 include/linux/list.h:list_del
Complexity 1 include/linux/err.h:IS_ERR
Complexity 1 arch/x86/include/asm/current.h:get_current
Complexity 1 arch/x86/include/asm/atomic.h:arch_atomic_read
Complexity 1 arch/x86/include/asm/atomic.h:arch_atomic_inc
Complexity 1 arch/x86/include/asm/atomic.h:arch_atomic_dec_and_test
Complexity 1 include/asm-generic/atomic-instrumented.h:atomic_read
Complexity 1 include/asm-generic/atomic-instrumented.h:atomic_inc
Complexity 1 include/asm-generic/atomic-instrumented.h:atomic_dec_and_test
Complexity 1 include/asm-generic/getorder.h:__get_order
Complexity 3 include/linux/bitmap.h:bitmap_zero
Complexity 1 include/linux/jiffies.h:_msecs_to_jiffies
Complexity 3 include/linux/jiffies.h:msecs_to_jiffies
Complexity 70 include/linux/ktime.h:ktime_divns
Complexity 1 include/linux/ktime.h:ktime_to_us
Complexity 1 include/linux/mmzone.h:pfn_to_section_nr
Complexity 2 include/linux/mmzone.h:__nr_to_section
Complexity 1 include/linux/mmzone.h:__section_mem_map_addr
Complexity 1 include/linux/mmzone.h:__pfn_to_section
Complexity 1 include/linux/kobject.h:kobject_name
Complexity 2 include/linux/device.h:dev_name
Complexity 1 include/linux/dma-debug.h:debug_dma_map_page
Complexity 1 include/linux/dma-debug.h:debug_dma_mapping_error
Complexity 1 include/linux/dma-mapping.h:valid_dma_direction
Complexity 1 arch/x86/include/asm/dma-mapping.h:get_arch_dma_ops
Complexity 4 include/linux/dma-mapping.h:get_dma_ops
Complexity 1 include/linux/dma-mapping.h:dma_map_page_attrs
Complexity 2 include/linux/dma-mapping.h:dma_mapping_error
Complexity 1 include/linux/dmaengine.h:dma_submit_error
Complexity 1 include/linux/dmaengine.h:dma_chan_name
Complexity 2 include/linux/dmaengine.h:dmaengine_terminate_all
Complexity 1 include/linux/dmaengine.h:dmaf_continue
Complexity 1 include/linux/dmaengine.h:dmaf_p_disabled_continue
Complexity 1 include/linux/dmaengine.h:dma_dev_has_pq_continue
Complexity 1 include/linux/dmaengine.h:dma_dev_to_maxpq
Complexity 4 include/linux/dmaengine.h:dma_maxpq
Complexity 1 include/linux/dmaengine.h:__dma_cap_set
Complexity 1 include/linux/dmaengine.h:__dma_cap_zero
Complexity 2 include/linux/dmaengine.h:__dma_has_cap
Complexity 1 include/linux/dmaengine.h:dma_async_issue_pending
Complexity 3 include/linux/dmaengine.h:dma_async_is_tx_complete
Complexity 2 include/linux/freezer.h:freezing
Complexity 2 include/linux/freezer.h:try_to_freeze_unsafe
Complexity 2 include/linux/freezer.h:try_to_freeze
Complexity 1 include/linux/kasan.h:kasan_kmalloc
Complexity 28 include/linux/slab.h:kmalloc_index
Complexity 1 include/linux/slab.h:kmem_cache_alloc_trace
Complexity 1 include/linux/slab.h:kmalloc_order_trace
Complexity 67 include/linux/slab.h:kmalloc_large
Complexity 5 include/linux/slab.h:kmalloc
Complexity 5 include/linux/slab.h:kmalloc_array
Complexity 1 include/linux/slab.h:kcalloc
Complexity 1 include/linux/slab.h:kzalloc
Complexity 2 include/linux/sched/task.h:put_task_struct
Complexity 2 drivers/dma/dmatest.c:gen_inv_idx
Complexity 1 drivers/dma/dmatest.c:gen_src_value
Complexity 1 drivers/dma/dmatest.c:gen_dst_value
Complexity 5 drivers/dma/dmatest.c:dmatest_init_srcs
Complexity 5 drivers/dma/dmatest.c:dmatest_init_dsts
Complexity 2 drivers/dma/dmatest.c:min_odd
Complexity 8 drivers/dma/dmatest.c:is_threaded_test_run
Complexity 5 drivers/dma/dmatest.c:dmatest_mismatch
Complexity 6 drivers/dma/dmatest.c:dmatest_verify
Complexity 1 drivers/dma/dmatest.c:result
Complexity 1 drivers/dma/dmatest.c:dbg_result
Complexity 5 drivers/dma/dmatest.c:dmatest_cleanup_channel
Complexity 5 drivers/dma/dmatest.c:stop_threaded_test
Complexity 2 drivers/dma/dmatest.c:dmatest_run_get
Complexity 1 drivers/dma/dmatest.c:dmatest_exit
Complexity 2 drivers/dma/dmatest.c:dmatest_match_channel
Complexity 2 drivers/dma/dmatest.c:dmatest_match_device
Complexity 3 drivers/dma/dmatest.c:filter
Complexity 69 drivers/dma/dmatest.c:dmatest_persec
Complexity 1 drivers/dma/dmatest.c:dmatest_KBs
Complexity 8 drivers/dma/dmatest.c:dmatest_add_threads
Complexity 8 drivers/dma/dmatest.c:dmatest_add_channel
Complexity 5 drivers/dma/dmatest.c:request_channels
Complexity 1 drivers/dma/dmatest.c:run_threaded_test
Complexity 2 drivers/dma/dmatest.c:restart_threaded_test
Complexity 4 drivers/dma/dmatest.c:dmatest_run_set
Complexity 4 drivers/dma/dmatest.c:dmatest_callback
Complexity 1 drivers/dma/dmatest.c:dmatest_random
Complexity 52 drivers/dma/dmatest.c:dmatest_func
Complexity 4 drivers/dma/dmatest.c:dmatest_wait_get
Complexity 6 drivers/dma/dmatest.c:dmatest_init
In function 'dmatest_func':
matest.c:806:1: warning: the frame size of 4264 bytes is larger than 2048 bytes [-Wframe-larger-than=]
2013-03-04 425
2008-07-08 426 /*
2008-07-08 427 * This function repeatedly tests DMA transfers of various lengths and
2009-03-25 428 * offsets for a given operation type until it is told to exit by
2009-03-25 429 * kthread_stop(). There may be multiple threads running this function
2009-03-25 430 * in parallel for a single channel, and there may be multiple channels
2009-03-25 431 * being tested in parallel.
2008-07-08 432 *
2008-07-08 433 * Before each test, the source and destination buffer is initialized
2008-07-08 434 * with a known pattern. This pattern is different depending on
2008-07-08 435 * whether it's in an area which is supposed to be copied or
2008-07-08 436 * overwritten, and different in the source and destination buffers.
2008-07-08 437 * So if the DMA engine doesn't copy exactly what we tell it to copy,
2008-07-08 438 * we'll notice.
2008-07-08 439 */
2008-07-08 440 static int dmatest_func(void *data)
2008-07-08 441 {
2008-07-08 442 struct dmatest_thread *thread = data;
2017-11-27 443 struct dmatest_done *done = &thread->test_done;
2013-03-04 444 struct dmatest_info *info;
2013-03-04 445 struct dmatest_params *params;
2008-07-08 446 struct dma_chan *chan;
2012-10-28 447 struct dma_device *dev;
2008-07-08 448 unsigned int error_count;
2008-07-08 449 unsigned int failed_tests = 0;
2008-07-08 450 unsigned int total_tests = 0;
2008-07-08 451 dma_cookie_t cookie;
2008-07-08 452 enum dma_status status;
2009-03-25 453 enum dma_ctrl_flags flags;
2013-03-04 454 u8 *pq_coefs = NULL;
2008-07-08 455 int ret;
2009-03-25 456 int src_cnt;
2009-03-25 457 int dst_cnt;
2009-03-25 458 int i;
2016-09-01 459 ktime_t ktime, start, diff;
2016-12-25 460 ktime_t filltime = 0;
2016-12-25 461 ktime_t comparetime = 0;
2013-11-06 462 s64 runtime = 0;
2013-11-06 463 unsigned long long total_len = 0;
2016-11-29 464 u8 align = 0;
2017-06-29 465 bool is_memset = false;
2008-07-08 466
2011-11-23 467 set_freezable();
2008-07-08 468
2008-07-08 469 ret = -ENOMEM;
2008-07-08 470
2008-07-08 471 smp_rmb();
2013-03-04 472 info = thread->info;
2013-03-04 473 params = &info->params;
2008-07-08 474 chan = thread->chan;
2012-10-28 475 dev = chan->device;
2016-11-29 476 if (thread->type == DMA_MEMCPY) {
2016-11-29 477 align = dev->copy_align;
2009-03-25 478 src_cnt = dst_cnt = 1;
2017-06-29 479 } else if (thread->type == DMA_MEMSET) {
2017-06-29 480 align = dev->fill_align;
2017-06-29 481 src_cnt = dst_cnt = 1;
2017-06-29 482 is_memset = true;
2016-11-29 483 } else if (thread->type == DMA_XOR) {
2012-10-28 484 /* force odd to ensure dst = src */
2013-03-04 485 src_cnt = min_odd(params->xor_sources | 1, dev->max_xor);
2009-03-25 486 dst_cnt = 1;
2016-11-29 487 align = dev->xor_align;
2009-08-29 488 } else if (thread->type == DMA_PQ) {
2012-10-28 489 /* force odd to ensure dst = src */
2013-03-04 490 src_cnt = min_odd(params->pq_sources | 1, dma_maxpq(dev, 0));
2009-08-29 491 dst_cnt = 2;
2016-11-29 492 align = dev->pq_align;
2013-03-04 493
2013-03-04 494 pq_coefs = kmalloc(params->pq_sources + 1, GFP_KERNEL);
2013-03-04 495 if (!pq_coefs)
2013-03-04 496 goto err_thread_type;
2013-03-04 497
2010-02-15 498 for (i = 0; i < src_cnt; i++)
2009-08-29 499 pq_coefs[i] = 1;
2009-03-25 500 } else
2013-03-04 501 goto err_thread_type;
2009-03-25 502
2009-03-25 503 thread->srcs = kcalloc(src_cnt + 1, sizeof(u8 *), GFP_KERNEL);
2009-03-25 504 if (!thread->srcs)
2009-03-25 505 goto err_srcs;
2016-11-29 506
2016-11-29 507 thread->usrcs = kcalloc(src_cnt + 1, sizeof(u8 *), GFP_KERNEL);
2016-11-29 508 if (!thread->usrcs)
2016-11-29 509 goto err_usrcs;
2016-11-29 510
2009-03-25 511 for (i = 0; i < src_cnt; i++) {
2016-11-29 512 thread->usrcs[i] = kmalloc(params->buf_size + align,
2016-11-29 513 GFP_KERNEL);
2016-11-29 514 if (!thread->usrcs[i])
2009-03-25 515 goto err_srcbuf;
2016-11-29 516
2016-11-29 517 /* align srcs to alignment restriction */
2016-11-29 518 if (align)
2016-11-29 519 thread->srcs[i] = PTR_ALIGN(thread->usrcs[i], align);
2016-11-29 520 else
2016-11-29 521 thread->srcs[i] = thread->usrcs[i];
2009-03-25 522 }
2009-03-25 523 thread->srcs[i] = NULL;
2009-03-25 524
2009-03-25 525 thread->dsts = kcalloc(dst_cnt + 1, sizeof(u8 *), GFP_KERNEL);
2009-03-25 526 if (!thread->dsts)
2009-03-25 527 goto err_dsts;
2016-11-29 528
2016-11-29 529 thread->udsts = kcalloc(dst_cnt + 1, sizeof(u8 *), GFP_KERNEL);
2016-11-29 530 if (!thread->udsts)
2016-11-29 531 goto err_udsts;
2016-11-29 532
2009-03-25 533 for (i = 0; i < dst_cnt; i++) {
2016-11-29 534 thread->udsts[i] = kmalloc(params->buf_size + align,
2016-11-29 535 GFP_KERNEL);
2016-11-29 536 if (!thread->udsts[i])
2009-03-25 537 goto err_dstbuf;
2016-11-29 538
2016-11-29 539 /* align dsts to alignment restriction */
2016-11-29 540 if (align)
2016-11-29 541 thread->dsts[i] = PTR_ALIGN(thread->udsts[i], align);
2016-11-29 542 else
2016-11-29 543 thread->dsts[i] = thread->udsts[i];
2009-03-25 544 }
2009-03-25 545 thread->dsts[i] = NULL;
2009-03-25 546
2009-03-25 547 set_user_nice(current, 10);
2009-03-25 548
2011-03-03 549 /*
Zolnierkiewicz 2013-10-18 550 * src and dst buffers are freed by ourselves below
2011-03-03 551 */
Zolnierkiewicz 2013-10-18 552 flags = DMA_CTRL_ACK | DMA_PREP_INTERRUPT;
2008-07-08 553
2013-11-06 554 ktime = ktime_get();
2009-07-03 555 while (!kthread_should_stop()
2013-03-04 556 && !(params->iterations && total_tests >= params->iterations)) {
2009-03-25 557 struct dma_async_tx_descriptor *tx = NULL;
2013-11-06 558 struct dmaengine_unmap_data *um;
2018-04-09 559 /* total buffer count must fit into u8 */
2018-04-09 560 dma_addr_t srcs[255];
2013-11-06 561 dma_addr_t *dsts;
2014-10-22 562 unsigned int src_off, dst_off, len;
2009-01-13 563
2008-07-08 564 total_tests++;
2008-07-08 565
2017-04-27 566 /* Check if buffer count fits into map count variable (u8) */
2017-04-27 567 if ((src_cnt + dst_cnt) >= 255) {
2017-04-27 568 pr_err("too many buffers (%d of 255 supported)\n",
2017-04-27 569 src_cnt + dst_cnt);
2017-04-27 570 break;
2017-04-27 571 }
2017-04-27 572
2013-03-04 573 if (1 << align > params->buf_size) {
2009-12-04 574 pr_err("%u-byte buffer too small for %d-byte alignment\n",
2013-03-04 575 params->buf_size, 1 << align);
2009-12-04 576 break;
2009-12-04 577 }
2009-12-04 578
2014-10-22 579 if (params->noverify)
2013-11-06 580 len = params->buf_size;
2014-10-22 581 else
2013-03-04 582 len = dmatest_random() % params->buf_size + 1;
2014-10-22 583
2009-09-08 584 len = (len >> align) << align;
2009-12-04 585 if (!len)
2009-12-04 586 len = 1 << align;
2014-10-22 587
2014-10-22 588 total_len += len;
2014-10-22 589
2014-10-22 590 if (params->noverify) {
2014-10-22 591 src_off = 0;
2014-10-22 592 dst_off = 0;
2014-10-22 593 } else {
2016-09-01 594 start = ktime_get();
2013-03-04 595 src_off = dmatest_random() % (params->buf_size - len + 1);
2013-03-04 596 dst_off = dmatest_random() % (params->buf_size - len + 1);
2009-12-04 597
2009-09-08 598 src_off = (src_off >> align) << align;
2009-09-08 599 dst_off = (dst_off >> align) << align;
2009-09-08 600
2013-11-06 601 dmatest_init_srcs(thread->srcs, src_off, len,
2017-06-29 602 params->buf_size, is_memset);
2013-11-06 603 dmatest_init_dsts(thread->dsts, dst_off, len,
2017-06-29 604 params->buf_size, is_memset);
2016-09-01 605
2016-09-01 606 diff = ktime_sub(ktime_get(), start);
2016-09-01 607 filltime = ktime_add(filltime, diff);
2013-11-06 608 }
2009-03-25 609
2013-11-06 610 um = dmaengine_get_unmap_data(dev->dev, src_cnt + dst_cnt,
2013-11-06 611 GFP_KERNEL);
2013-11-06 612 if (!um) {
2013-11-06 613 failed_tests++;
2013-11-06 614 result("unmap data NULL", total_tests,
2013-11-06 615 src_off, dst_off, len, ret);
2013-11-06 616 continue;
2013-11-06 617 }
2008-07-08 618
2013-11-06 619 um->len = params->buf_size;
2013-11-06 620 for (i = 0; i < src_cnt; i++) {
2013-12-09 621 void *buf = thread->srcs[i];
2013-11-06 622 struct page *pg = virt_to_page(buf);
2017-04-22 623 unsigned long pg_off = offset_in_page(buf);
2013-11-06 624
2013-11-06 625 um->addr[i] = dma_map_page(dev->dev, pg, pg_off,
2013-11-06 626 um->len, DMA_TO_DEVICE);
2013-11-06 627 srcs[i] = um->addr[i] + src_off;
2013-11-06 628 ret = dma_mapping_error(dev->dev, um->addr[i]);
2012-12-17 629 if (ret) {
2013-11-06 630 dmaengine_unmap_put(um);
2013-11-06 631 result("src mapping error", total_tests,
2013-11-06 632 src_off, dst_off, len, ret);
2012-12-17 633 failed_tests++;
2012-12-17 634 continue;
2012-12-17 635 }
2013-11-06 636 um->to_cnt++;
2009-03-25 637 }
2009-01-13 638 /* map with DMA_BIDIRECTIONAL to force writeback/invalidate */
2013-11-06 639 dsts = &um->addr[src_cnt];
2009-03-25 640 for (i = 0; i < dst_cnt; i++) {
2013-12-09 641 void *buf = thread->dsts[i];
2013-11-06 642 struct page *pg = virt_to_page(buf);
2017-04-22 643 unsigned long pg_off = offset_in_page(buf);
2013-11-06 644
2013-11-06 645 dsts[i] = dma_map_page(dev->dev, pg, pg_off, um->len,
2009-03-25 646 DMA_BIDIRECTIONAL);
2013-11-06 647 ret = dma_mapping_error(dev->dev, dsts[i]);
2012-12-17 648 if (ret) {
2013-11-06 649 dmaengine_unmap_put(um);
2013-11-06 650 result("dst mapping error", total_tests,
2013-11-06 651 src_off, dst_off, len, ret);
2012-12-17 652 failed_tests++;
2012-12-17 653 continue;
2012-12-17 654 }
2013-11-06 655 um->bidi_cnt++;
2009-03-25 656 }
2009-09-08 657
2009-03-25 658 if (thread->type == DMA_MEMCPY)
2009-03-25 659 tx = dev->device_prep_dma_memcpy(chan,
2013-11-06 660 dsts[0] + dst_off,
2013-11-06 661 srcs[0], len, flags);
2017-06-29 662 else if (thread->type == DMA_MEMSET)
2017-06-29 663 tx = dev->device_prep_dma_memset(chan,
2017-06-29 664 dsts[0] + dst_off,
2017-06-29 665 *(thread->srcs[0] + src_off),
2017-06-29 666 len, flags);
2009-03-25 667 else if (thread->type == DMA_XOR)
2009-03-25 668 tx = dev->device_prep_dma_xor(chan,
2013-11-06 669 dsts[0] + dst_off,
2013-11-06 670 srcs, src_cnt,
2009-03-25 671 len, flags);
2009-08-29 672 else if (thread->type == DMA_PQ) {
2018-04-09 673 /* dst_cnt can't be more than u8 */
2018-04-09 674 dma_addr_t dma_pq[255];
2009-08-29 675
2009-08-29 676 for (i = 0; i < dst_cnt; i++)
2013-11-06 677 dma_pq[i] = dsts[i] + dst_off;
2013-11-06 678 tx = dev->device_prep_dma_pq(chan, dma_pq, srcs,
2010-02-15 679 src_cnt, pq_coefs,
2009-08-29 680 len, flags);
2009-08-29 681 }
2009-01-13 682
2009-01-13 683 if (!tx) {
2013-11-06 684 dmaengine_unmap_put(um);
2013-11-06 685 result("prep error", total_tests, src_off,
2013-11-06 686 dst_off, len, ret);
2009-01-13 687 msleep(100);
2009-01-13 688 failed_tests++;
2009-01-13 689 continue;
2009-01-13 690 }
2009-03-25 691
2017-11-27 692 done->done = false;
2009-03-25 693 tx->callback = dmatest_callback;
2017-11-27 694 tx->callback_param = done;
2009-01-13 695 cookie = tx->tx_submit(tx);
2009-01-13 696
2008-07-08 697 if (dma_submit_error(cookie)) {
2013-11-06 698 dmaengine_unmap_put(um);
2013-11-06 699 result("submit error", total_tests, src_off,
2013-11-06 700 dst_off, len, ret);
2008-07-08 701 msleep(100);
2008-07-08 702 failed_tests++;
2008-07-08 703 continue;
2008-07-08 704 }
2009-03-25 705 dma_async_issue_pending(chan);
2008-07-08 706
2017-11-27 707 wait_event_freezable_timeout(thread->done_wait, done->done,
2013-03-04 708 msecs_to_jiffies(params->timeout));
2011-08-18 709
2009-03-25 710 status = dma_async_is_tx_complete(chan, cookie, NULL, NULL);
2008-07-08 711
2017-11-27 712 if (!done->done) {
2013-11-06 713 dmaengine_unmap_put(um);
2013-11-06 714 result("test timed out", total_tests, src_off, dst_off,
2013-03-04 715 len, 0);
2008-07-08 716 failed_tests++;
2008-07-08 717 continue;
2013-10-16 718 } else if (status != DMA_COMPLETE) {
2013-11-06 719 dmaengine_unmap_put(um);
2013-11-06 720 result(status == DMA_ERROR ?
2013-11-06 721 "completion error status" :
2013-11-06 722 "completion busy status", total_tests, src_off,
2013-11-06 723 dst_off, len, ret);
2009-03-25 724 failed_tests++;
2009-03-25 725 continue;
2008-07-08 726 }
2009-03-25 727
2013-11-06 728 dmaengine_unmap_put(um);
2008-07-08 729
2013-11-06 730 if (params->noverify) {
2013-11-08 731 verbose_result("test passed", total_tests, src_off,
2013-11-08 732 dst_off, len, 0);
2013-11-06 733 continue;
2013-11-06 734 }
2008-07-08 735
2016-09-01 736 start = ktime_get();
2013-11-06 737 pr_debug("%s: verifying source buffer...\n", current->comm);
2013-11-06 738 error_count = dmatest_verify(thread->srcs, 0, src_off,
2017-06-29 739 0, PATTERN_SRC, true, is_memset);
2013-11-06 740 error_count += dmatest_verify(thread->srcs, src_off,
2013-11-06 741 src_off + len, src_off,
2017-06-29 742 PATTERN_SRC | PATTERN_COPY, true, is_memset);
2013-11-06 743 error_count += dmatest_verify(thread->srcs, src_off + len,
2013-11-06 744 params->buf_size, src_off + len,
2017-06-29 745 PATTERN_SRC, true, is_memset);
2013-11-06 746
2013-11-06 747 pr_debug("%s: verifying dest buffer...\n", current->comm);
2013-11-06 748 error_count += dmatest_verify(thread->dsts, 0, dst_off,
2017-06-29 749 0, PATTERN_DST, false, is_memset);
2017-06-29 750
2013-11-06 751 error_count += dmatest_verify(thread->dsts, dst_off,
2013-11-06 752 dst_off + len, src_off,
2017-06-29 753 PATTERN_SRC | PATTERN_COPY, false, is_memset);
2017-06-29 754
2013-11-06 755 error_count += dmatest_verify(thread->dsts, dst_off + len,
2013-11-06 756 params->buf_size, dst_off + len,
2017-06-29 757 PATTERN_DST, false, is_memset);
2008-07-08 758
2016-09-01 759 diff = ktime_sub(ktime_get(), start);
2016-09-01 760 comparetime = ktime_add(comparetime, diff);
2016-09-01 761
2008-07-08 762 if (error_count) {
2013-11-06 763 result("data error", total_tests, src_off, dst_off,
2013-03-04 764 len, error_count);
2008-07-08 765 failed_tests++;
2008-07-08 766 } else {
2013-11-08 767 verbose_result("test passed", total_tests, src_off,
2013-11-08 768 dst_off, len, 0);
2008-07-08 769 }
2008-07-08 770 }
2016-09-01 771 ktime = ktime_sub(ktime_get(), ktime);
2016-09-01 772 ktime = ktime_sub(ktime, comparetime);
2016-09-01 773 ktime = ktime_sub(ktime, filltime);
2016-09-01 774 runtime = ktime_to_us(ktime);
2008-07-08 775
2008-07-08 776 ret = 0;
2014-08-22 777 err_dstbuf:
2016-11-29 778 for (i = 0; thread->udsts[i]; i++)
2016-11-29 779 kfree(thread->udsts[i]);
2016-11-29 780 kfree(thread->udsts);
2016-11-29 781 err_udsts:
2009-03-25 782 kfree(thread->dsts);
2009-03-25 783 err_dsts:
2014-08-22 784 err_srcbuf:
2016-11-29 785 for (i = 0; thread->usrcs[i]; i++)
2016-11-29 786 kfree(thread->usrcs[i]);
2016-11-29 787 kfree(thread->usrcs);
2016-11-29 788 err_usrcs:
2009-03-25 789 kfree(thread->srcs);
2009-03-25 790 err_srcs:
2013-03-04 791 kfree(pq_coefs);
2013-03-04 792 err_thread_type:
2013-11-06 793 pr_info("%s: summary %u tests, %u failures %llu iops %llu KB/s (%d)\n",
2013-11-06 794 current->comm, total_tests, failed_tests,
2013-11-06 795 dmatest_persec(runtime, total_tests),
2013-11-06 796 dmatest_KBs(runtime, total_len), ret);
2009-07-03 797
2011-07-29 798 /* terminate all transfers on specified channels */
2017-11-27 799 if (ret || failed_tests)
2012-11-11 800 dmaengine_terminate_all(chan);
2012-11-09 801
2013-03-04 802 thread->done = true;
2013-11-06 803 wake_up(&thread_wait);
2009-07-03 804
2008-07-08 805 return ret;
2008-07-08 @806 }
2008-07-08 807
at line 806 was first introduced by commit
2460192c07b56f4fe9cd82632 dmatest: Simple DMA memcpy test client
Skinnemoen <[email protected]>
Williams <[email protected]>
Open Source Technology Center
s.01.org/pipermail/kbuild-all">https://lists.01.org/pipermail/kbuild-all Intel Corporation

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2018-04-10 15:38:24

by Vinod Koul

[permalink] [raw]

Subject: Re: [PATCH] dmaengine: dmatest: Remove use of VLAs

On Mon, Apr 09, 2018 at 04:14:20PM -0700, Laura Abbott wrote:
> On 04/09/2018 03:48 PM, Sinan Kaya wrote:
> >On 4/9/2018 5:06 PM, Laura Abbott wrote:
> >>+ /* dst_cnt can't be more than u8 */
> >>+ dma_addr_t dma_pq[255];
> >
> >This is 2k stack space on 64 bit architectures. Isn't that a lot?
> >
>
> Depends on your definition of 'a lot'. My assumption was that
> since this was a test module there would be some willingness
> to be a bit more generous. The problem is the array size is
> based off of the parameters passed in, although oddly enough
> it's based off of the minimum of two variables. If you have
> a suggestion for a tighter bound we can use that. Another
> option is to just switch to allocating the array with kmalloc.
> That might be reasonable here since there's other setup
> that happens before the test starts.

Being a test module I don't think I would have too many qualms with current
approach :) said that kmalloc approach seems reasonable too..

Thanks
--
~Vinod