2023-07-25 11:56:35

by Vijaya Krishna Nivarthi

Subject: [PATCH 2/4] spi: spi-qcom-qspi: Use GFP_ATOMIC flag while allocating for descriptor

While allocating for DMA descriptor, GFP_KERNEL flag is being used and
this allocation happens within critical section with spinlock acquired.
This generates a static checker warning.

Use GFP_ATOMIC to prevent sleeping; and since this increases chances of
allocation failure, add handling accordingly.

Reported-by: Dan Carpenter <[email protected]>
Closes: https://lore.kernel.org/all/[email protected]/
Signed-off-by: Vijaya Krishna Nivarthi <[email protected]>
---
drivers/spi/spi-qcom-qspi.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/spi/spi-qcom-qspi.c b/drivers/spi/spi-qcom-qspi.c
index b995542..b938908 100644
--- a/drivers/spi/spi-qcom-qspi.c
+++ b/drivers/spi/spi-qcom-qspi.c
@@ -308,9 +308,11 @@ static int qcom_qspi_alloc_desc(struct qcom_qspi *ctrl, dma_addr_t dma_ptr,
dma_addr_t dma_cmd_desc;

/* allocate for dma cmd descriptor */
- virt_cmd_desc = dma_pool_alloc(ctrl->dma_cmd_pool, GFP_KERNEL | __GFP_ZERO, &dma_cmd_desc);
- if (!virt_cmd_desc)
- return -ENOMEM;
+ virt_cmd_desc = dma_pool_alloc(ctrl->dma_cmd_pool, GFP_ATOMIC | __GFP_ZERO, &dma_cmd_desc);
+ if (!virt_cmd_desc) {
+ dev_warn_once(ctrl->dev, "Couldn't find memory for descriptor\n");
+ return -EAGAIN;
+ }

ctrl->virt_cmd_desc[ctrl->n_cmd_desc] = virt_cmd_desc;
ctrl->dma_cmd_desc[ctrl->n_cmd_desc] = dma_cmd_desc;
--
Qualcomm INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, hosted by the Linux Foundation.

2023-07-25 19:13:11

by Doug Anderson

Subject: Re: [PATCH 2/4] spi: spi-qcom-qspi: Use GFP_ATOMIC flag while allocating for descriptor

Hi,

On Tue, Jul 25, 2023 at 4:48 AM Vijaya Krishna Nivarthi
<[email protected]> wrote:
>
> While allocating for DMA descriptor, GFP_KERNEL flag is being used and
> this allocation happens within critical section with spinlock acquired.
> This generates a static checker warning.
>
> Use GFP_ATOMIC to prevent sleeping; and since this increases chances of
> allocation failure, add handling accordingly.
>
> Reported-by: Dan Carpenter <[email protected]>
> Closes: https://lore.kernel.org/all/[email protected]/
> Signed-off-by: Vijaya Krishna Nivarthi <[email protected]>
> ---
> drivers/spi/spi-qcom-qspi.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)

Fixes: b5762d95607e ("spi: spi-qcom-qspi: Add DMA mode support")
Reviewed-by: Douglas Anderson <[email protected]>