2018-04-11 01:15:30

by Laura Abbott

Subject: [PATCHv2] 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 test already pre-allocates some buffers with kmalloc so turn
the two VLAs in to pre-allocated kmalloc buffers.

Signed-off-by: Laura Abbott <[email protected]>
---
v2: Switch to using kmalloc buffers instead of putting a large array on
the stack.
---
drivers/dma/dmatest.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/dma/dmatest.c b/drivers/dma/dmatest.c
index 80cc2be6483c..9730956dfbe3 100644
--- a/drivers/dma/dmatest.c
+++ b/drivers/dma/dmatest.c
@@ -463,6 +463,8 @@ static int dmatest_func(void *data)
unsigned long long total_len = 0;
u8 align = 0;
bool is_memset = false;
+ dma_addr_t *srcs;
+ dma_addr_t *dma_pq;

set_freezable();

@@ -546,6 +548,14 @@ static int dmatest_func(void *data)

set_user_nice(current, 10);

+ srcs = kcalloc(src_cnt, sizeof(dma_addr_t), GFP_KERNEL);
+ if (!srcs)
+ goto err_dstbuf;
+
+ dma_pq = kcalloc(dst_cnt, sizeof(dma_addr_t), GFP_KERNEL);
+ if (!dma_pq)
+ goto err_srcs_array;
+
/*
* src and dst buffers are freed by ourselves below
*/
@@ -556,7 +566,6 @@ 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];
dma_addr_t *dsts;
unsigned int src_off, dst_off, len;

@@ -669,8 +678,6 @@ static int dmatest_func(void *data)
srcs, src_cnt,
len, flags);
else if (thread->type == DMA_PQ) {
- dma_addr_t dma_pq[dst_cnt];
-
for (i = 0; i < dst_cnt; i++)
dma_pq[i] = dsts[i] + dst_off;
tx = dev->device_prep_dma_pq(chan, dma_pq, srcs,
@@ -772,6 +779,9 @@ static int dmatest_func(void *data)
runtime = ktime_to_us(ktime);

ret = 0;
+ kfree(dma_pq);
+err_srcs_array:
+ kfree(srcs);
err_dstbuf:
for (i = 0; thread->udsts[i]; i++)
kfree(thread->udsts[i]);
--
2.14.3

2018-04-12 02:30:14

by Sinan Kaya

Subject: Re: [PATCHv2] dmaengine: dmatest: Remove use of VLAs

On 4/10/2018 9:02 PM, Laura Abbott wrote:
> 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 test already pre-allocates some buffers with kmalloc so turn
> the two VLAs in to pre-allocated kmalloc buffers.
>
> Signed-off-by: Laura Abbott <[email protected]>
> ---
> v2: Switch to using kmalloc buffers instead of putting a large array on
> the stack.
> ---
> drivers/dma/dmatest.c | 16 +++++++++++++---
> 1 file changed, 13 insertions(+), 3 deletions(-)
>

Reviewed-by: Sinan Kaya <[email protected]>


--
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.

2018-04-16 15:34:12

by Vinod Koul

Subject: Re: [PATCHv2] dmaengine: dmatest: Remove use of VLAs

On Tue, Apr 10, 2018 at 06:02:16PM -0700, Laura Abbott wrote:
> 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 test already pre-allocates some buffers with kmalloc so turn
> the two VLAs in to pre-allocated kmalloc buffers.

Applied, thanks

--
~Vinod