dma: dw-edma: Fix build warning in dw_edma_pcie_probe()

[PATCH RFC] dma: dw-edma: Fix build warning in dw_edma_pcie_probe()

Posted by Abinash Singh 3 months ago

The function dw_edma_pcie_probe() in dw-edma-pcie.c triggered a
frame size warning:
ld.lld:warning:
  drivers/dma/dw-edma/dw-edma-pcie.c:162:0: stack frame size (1040) exceeds limit (1024) in function 'dw_edma_pcie_probe'

This patch reduces the stack usage by dynamically allocating the
`vsec_data` structure using kmalloc(), rather than placing it on
the stack. This eliminates the overflow warning and improves kernel
robustness.

Signed-off-by: Abinash Singh <abinashsinghlalotra@gmail.com>
---
The stack usage was further confirmed by using -fstack-usage flag.
it was usiing 928 bytes:
..............................
drivers/dma/dw-edma/dw-edma-pcie.c:377:cleanup_module   8       static
drivers/dma/dw-edma/dw-edma-pcie.c:160:dw_edma_pcie_probe       928     static
......................................
After applying the patch it becomes :
.........
drivers/dma/dw-edma/dw-edma-pcie.c:381:cleanup_module   8       static
drivers/dma/dw-edma/dw-edma-pcie.c:160:dw_edma_pcie_probe       120     static
.......

This function is used for probing . So dynamic allocation will not create
any issues.

Thank You
---
 drivers/dma/dw-edma/dw-edma-pcie.c | 60 ++++++++++++++++--------------
 1 file changed, 32 insertions(+), 28 deletions(-)

diff --git a/drivers/dma/dw-edma/dw-edma-pcie.c b/drivers/dma/dw-edma/dw-edma-pcie.c
index 49f09998e5c0..1536395eacd2 100644
--- a/drivers/dma/dw-edma/dw-edma-pcie.c
+++ b/drivers/dma/dw-edma/dw-edma-pcie.c
@@ -161,12 +161,16 @@ static int dw_edma_pcie_probe(struct pci_dev *pdev,
 			      const struct pci_device_id *pid)
 {
 	struct dw_edma_pcie_data *pdata = (void *)pid->driver_data;
-	struct dw_edma_pcie_data vsec_data;
+	struct dw_edma_pcie_data *vsec_data __free(kfree) = NULL;
 	struct device *dev = &pdev->dev;
 	struct dw_edma_chip *chip;
 	int err, nr_irqs;
 	int i, mask;
 
+	vsec_data = kmalloc(sizeof(*vsec_data), GFP_KERNEL);
+	if (!vsec_data)
+		return -ENOMEM;
+
 	/* Enable PCI device */
 	err = pcim_enable_device(pdev);
 	if (err) {
@@ -174,23 +178,23 @@ static int dw_edma_pcie_probe(struct pci_dev *pdev,
 		return err;
 	}
 
-	memcpy(&vsec_data, pdata, sizeof(struct dw_edma_pcie_data));
+	memcpy(vsec_data, pdata, sizeof(struct dw_edma_pcie_data));
 
 	/*
 	 * Tries to find if exists a PCIe Vendor-Specific Extended Capability
 	 * for the DMA, if one exists, then reconfigures it.
 	 */
-	dw_edma_pcie_get_vsec_dma_data(pdev, &vsec_data);
+	dw_edma_pcie_get_vsec_dma_data(pdev, vsec_data);
 
 	/* Mapping PCI BAR regions */
-	mask = BIT(vsec_data.rg.bar);
-	for (i = 0; i < vsec_data.wr_ch_cnt; i++) {
-		mask |= BIT(vsec_data.ll_wr[i].bar);
-		mask |= BIT(vsec_data.dt_wr[i].bar);
+	mask = BIT(vsec_data->rg.bar);
+	for (i = 0; i < vsec_data->wr_ch_cnt; i++) {
+		mask |= BIT(vsec_data->ll_wr[i].bar);
+		mask |= BIT(vsec_data->dt_wr[i].bar);
 	}
-	for (i = 0; i < vsec_data.rd_ch_cnt; i++) {
-		mask |= BIT(vsec_data.ll_rd[i].bar);
-		mask |= BIT(vsec_data.dt_rd[i].bar);
+	for (i = 0; i < vsec_data->rd_ch_cnt; i++) {
+		mask |= BIT(vsec_data->ll_rd[i].bar);
+		mask |= BIT(vsec_data->dt_rd[i].bar);
 	}
 	err = pcim_iomap_regions(pdev, mask, pci_name(pdev));
 	if (err) {
@@ -213,7 +217,7 @@ static int dw_edma_pcie_probe(struct pci_dev *pdev,
 		return -ENOMEM;
 
 	/* IRQs allocation */
-	nr_irqs = pci_alloc_irq_vectors(pdev, 1, vsec_data.irqs,
+	nr_irqs = pci_alloc_irq_vectors(pdev, 1, vsec_data->irqs,
 					PCI_IRQ_MSI | PCI_IRQ_MSIX);
 	if (nr_irqs < 1) {
 		pci_err(pdev, "fail to alloc IRQ vector (number of IRQs=%u)\n",
@@ -224,22 +228,22 @@ static int dw_edma_pcie_probe(struct pci_dev *pdev,
 	/* Data structure initialization */
 	chip->dev = dev;
 
-	chip->mf = vsec_data.mf;
+	chip->mf = vsec_data->mf;
 	chip->nr_irqs = nr_irqs;
 	chip->ops = &dw_edma_pcie_plat_ops;
 
-	chip->ll_wr_cnt = vsec_data.wr_ch_cnt;
-	chip->ll_rd_cnt = vsec_data.rd_ch_cnt;
+	chip->ll_wr_cnt = vsec_data->wr_ch_cnt;
+	chip->ll_rd_cnt = vsec_data->rd_ch_cnt;
 
-	chip->reg_base = pcim_iomap_table(pdev)[vsec_data.rg.bar];
+	chip->reg_base = pcim_iomap_table(pdev)[vsec_data->rg.bar];
 	if (!chip->reg_base)
 		return -ENOMEM;
 
 	for (i = 0; i < chip->ll_wr_cnt; i++) {
 		struct dw_edma_region *ll_region = &chip->ll_region_wr[i];
 		struct dw_edma_region *dt_region = &chip->dt_region_wr[i];
-		struct dw_edma_block *ll_block = &vsec_data.ll_wr[i];
-		struct dw_edma_block *dt_block = &vsec_data.dt_wr[i];
+		struct dw_edma_block *ll_block = &vsec_data->ll_wr[i];
+		struct dw_edma_block *dt_block = &vsec_data->dt_wr[i];
 
 		ll_region->vaddr.io = pcim_iomap_table(pdev)[ll_block->bar];
 		if (!ll_region->vaddr.io)
@@ -263,8 +267,8 @@ static int dw_edma_pcie_probe(struct pci_dev *pdev,
 	for (i = 0; i < chip->ll_rd_cnt; i++) {
 		struct dw_edma_region *ll_region = &chip->ll_region_rd[i];
 		struct dw_edma_region *dt_region = &chip->dt_region_rd[i];
-		struct dw_edma_block *ll_block = &vsec_data.ll_rd[i];
-		struct dw_edma_block *dt_block = &vsec_data.dt_rd[i];
+		struct dw_edma_block *ll_block = &vsec_data->ll_rd[i];
+		struct dw_edma_block *dt_block = &vsec_data->dt_rd[i];
 
 		ll_region->vaddr.io = pcim_iomap_table(pdev)[ll_block->bar];
 		if (!ll_region->vaddr.io)
@@ -298,31 +302,31 @@ static int dw_edma_pcie_probe(struct pci_dev *pdev,
 		pci_dbg(pdev, "Version:\tUnknown (0x%x)\n", chip->mf);
 
 	pci_dbg(pdev, "Registers:\tBAR=%u, off=0x%.8lx, sz=0x%zx bytes, addr(v=%p)\n",
-		vsec_data.rg.bar, vsec_data.rg.off, vsec_data.rg.sz,
+		vsec_data->rg.bar, vsec_data->rg.off, vsec_data->rg.sz,
 		chip->reg_base);
 
 
 	for (i = 0; i < chip->ll_wr_cnt; i++) {
 		pci_dbg(pdev, "L. List:\tWRITE CH%.2u, BAR=%u, off=0x%.8lx, sz=0x%zx bytes, addr(v=%p, p=%pa)\n",
-			i, vsec_data.ll_wr[i].bar,
-			vsec_data.ll_wr[i].off, chip->ll_region_wr[i].sz,
+			i, vsec_data->ll_wr[i].bar,
+			vsec_data->ll_wr[i].off, chip->ll_region_wr[i].sz,
 			chip->ll_region_wr[i].vaddr.io, &chip->ll_region_wr[i].paddr);
 
 		pci_dbg(pdev, "Data:\tWRITE CH%.2u, BAR=%u, off=0x%.8lx, sz=0x%zx bytes, addr(v=%p, p=%pa)\n",
-			i, vsec_data.dt_wr[i].bar,
-			vsec_data.dt_wr[i].off, chip->dt_region_wr[i].sz,
+			i, vsec_data->dt_wr[i].bar,
+			vsec_data->dt_wr[i].off, chip->dt_region_wr[i].sz,
 			chip->dt_region_wr[i].vaddr.io, &chip->dt_region_wr[i].paddr);
 	}
 
 	for (i = 0; i < chip->ll_rd_cnt; i++) {
 		pci_dbg(pdev, "L. List:\tREAD CH%.2u, BAR=%u, off=0x%.8lx, sz=0x%zx bytes, addr(v=%p, p=%pa)\n",
-			i, vsec_data.ll_rd[i].bar,
-			vsec_data.ll_rd[i].off, chip->ll_region_rd[i].sz,
+			i, vsec_data->ll_rd[i].bar,
+			vsec_data->ll_rd[i].off, chip->ll_region_rd[i].sz,
 			chip->ll_region_rd[i].vaddr.io, &chip->ll_region_rd[i].paddr);
 
 		pci_dbg(pdev, "Data:\tREAD CH%.2u, BAR=%u, off=0x%.8lx, sz=0x%zx bytes, addr(v=%p, p=%pa)\n",
-			i, vsec_data.dt_rd[i].bar,
-			vsec_data.dt_rd[i].off, chip->dt_region_rd[i].sz,
+			i, vsec_data->dt_rd[i].bar,
+			vsec_data->dt_rd[i].off, chip->dt_region_rd[i].sz,
 			chip->dt_region_rd[i].vaddr.io, &chip->dt_region_rd[i].paddr);
 	}
 
-- 
2.43.0

Re: [PATCH RFC] dma: dw-edma: Fix build warning in dw_edma_pcie_probe()

Posted by Vinod Koul 2 months, 3 weeks ago

On Sat, 05 Jul 2025 21:30:55 +0530, Abinash Singh wrote:
> The function dw_edma_pcie_probe() in dw-edma-pcie.c triggered a
> frame size warning:
> ld.lld:warning:
>   drivers/dma/dw-edma/dw-edma-pcie.c:162:0: stack frame size (1040) exceeds limit (1024) in function 'dw_edma_pcie_probe'
> 
> This patch reduces the stack usage by dynamically allocating the
> `vsec_data` structure using kmalloc(), rather than placing it on
> the stack. This eliminates the overflow warning and improves kernel
> robustness.
> 
> [...]

Applied, thanks!

[1/1] dma: dw-edma: Fix build warning in dw_edma_pcie_probe()
      commit: 3df63fa8f2afd051848e37ef1b8299dee28d4f87

Best regards,
-- 
~Vinod

Re: [PATCH RFC] dma: dw-edma: Fix build warning in dw_edma_pcie_probe()

Posted by Manivannan Sadhasivam 3 months ago

On Sat, Jul 05, 2025 at 09:30:55PM GMT, Abinash Singh wrote:
> The function dw_edma_pcie_probe() in dw-edma-pcie.c triggered a
> frame size warning:
> ld.lld:warning:
>   drivers/dma/dw-edma/dw-edma-pcie.c:162:0: stack frame size (1040) exceeds limit (1024) in function 'dw_edma_pcie_probe'
> 
> This patch reduces the stack usage by dynamically allocating the
> `vsec_data` structure using kmalloc(), rather than placing it on
> the stack. This eliminates the overflow warning and improves kernel
> robustness.
> 
> Signed-off-by: Abinash Singh <abinashsinghlalotra@gmail.com>

Acked-by: Manivannan Sadhasivam <mani@kernel.org>

- Mani

> ---
> The stack usage was further confirmed by using -fstack-usage flag.
> it was usiing 928 bytes:
> ..............................
> drivers/dma/dw-edma/dw-edma-pcie.c:377:cleanup_module   8       static
> drivers/dma/dw-edma/dw-edma-pcie.c:160:dw_edma_pcie_probe       928     static
> ......................................
> After applying the patch it becomes :
> .........
> drivers/dma/dw-edma/dw-edma-pcie.c:381:cleanup_module   8       static
> drivers/dma/dw-edma/dw-edma-pcie.c:160:dw_edma_pcie_probe       120     static
> .......
> 
> This function is used for probing . So dynamic allocation will not create
> any issues.
> 
> Thank You
> ---
>  drivers/dma/dw-edma/dw-edma-pcie.c | 60 ++++++++++++++++--------------
>  1 file changed, 32 insertions(+), 28 deletions(-)
> 
> diff --git a/drivers/dma/dw-edma/dw-edma-pcie.c b/drivers/dma/dw-edma/dw-edma-pcie.c
> index 49f09998e5c0..1536395eacd2 100644
> --- a/drivers/dma/dw-edma/dw-edma-pcie.c
> +++ b/drivers/dma/dw-edma/dw-edma-pcie.c
> @@ -161,12 +161,16 @@ static int dw_edma_pcie_probe(struct pci_dev *pdev,
>  			      const struct pci_device_id *pid)
>  {
>  	struct dw_edma_pcie_data *pdata = (void *)pid->driver_data;
> -	struct dw_edma_pcie_data vsec_data;
> +	struct dw_edma_pcie_data *vsec_data __free(kfree) = NULL;
>  	struct device *dev = &pdev->dev;
>  	struct dw_edma_chip *chip;
>  	int err, nr_irqs;
>  	int i, mask;
>  
> +	vsec_data = kmalloc(sizeof(*vsec_data), GFP_KERNEL);
> +	if (!vsec_data)
> +		return -ENOMEM;
> +
>  	/* Enable PCI device */
>  	err = pcim_enable_device(pdev);
>  	if (err) {
> @@ -174,23 +178,23 @@ static int dw_edma_pcie_probe(struct pci_dev *pdev,
>  		return err;
>  	}
>  
> -	memcpy(&vsec_data, pdata, sizeof(struct dw_edma_pcie_data));
> +	memcpy(vsec_data, pdata, sizeof(struct dw_edma_pcie_data));
>  
>  	/*
>  	 * Tries to find if exists a PCIe Vendor-Specific Extended Capability
>  	 * for the DMA, if one exists, then reconfigures it.
>  	 */
> -	dw_edma_pcie_get_vsec_dma_data(pdev, &vsec_data);
> +	dw_edma_pcie_get_vsec_dma_data(pdev, vsec_data);
>  
>  	/* Mapping PCI BAR regions */
> -	mask = BIT(vsec_data.rg.bar);
> -	for (i = 0; i < vsec_data.wr_ch_cnt; i++) {
> -		mask |= BIT(vsec_data.ll_wr[i].bar);
> -		mask |= BIT(vsec_data.dt_wr[i].bar);
> +	mask = BIT(vsec_data->rg.bar);
> +	for (i = 0; i < vsec_data->wr_ch_cnt; i++) {
> +		mask |= BIT(vsec_data->ll_wr[i].bar);
> +		mask |= BIT(vsec_data->dt_wr[i].bar);
>  	}
> -	for (i = 0; i < vsec_data.rd_ch_cnt; i++) {
> -		mask |= BIT(vsec_data.ll_rd[i].bar);
> -		mask |= BIT(vsec_data.dt_rd[i].bar);
> +	for (i = 0; i < vsec_data->rd_ch_cnt; i++) {
> +		mask |= BIT(vsec_data->ll_rd[i].bar);
> +		mask |= BIT(vsec_data->dt_rd[i].bar);
>  	}
>  	err = pcim_iomap_regions(pdev, mask, pci_name(pdev));
>  	if (err) {
> @@ -213,7 +217,7 @@ static int dw_edma_pcie_probe(struct pci_dev *pdev,
>  		return -ENOMEM;
>  
>  	/* IRQs allocation */
> -	nr_irqs = pci_alloc_irq_vectors(pdev, 1, vsec_data.irqs,
> +	nr_irqs = pci_alloc_irq_vectors(pdev, 1, vsec_data->irqs,
>  					PCI_IRQ_MSI | PCI_IRQ_MSIX);
>  	if (nr_irqs < 1) {
>  		pci_err(pdev, "fail to alloc IRQ vector (number of IRQs=%u)\n",
> @@ -224,22 +228,22 @@ static int dw_edma_pcie_probe(struct pci_dev *pdev,
>  	/* Data structure initialization */
>  	chip->dev = dev;
>  
> -	chip->mf = vsec_data.mf;
> +	chip->mf = vsec_data->mf;
>  	chip->nr_irqs = nr_irqs;
>  	chip->ops = &dw_edma_pcie_plat_ops;
>  
> -	chip->ll_wr_cnt = vsec_data.wr_ch_cnt;
> -	chip->ll_rd_cnt = vsec_data.rd_ch_cnt;
> +	chip->ll_wr_cnt = vsec_data->wr_ch_cnt;
> +	chip->ll_rd_cnt = vsec_data->rd_ch_cnt;
>  
> -	chip->reg_base = pcim_iomap_table(pdev)[vsec_data.rg.bar];
> +	chip->reg_base = pcim_iomap_table(pdev)[vsec_data->rg.bar];
>  	if (!chip->reg_base)
>  		return -ENOMEM;
>  
>  	for (i = 0; i < chip->ll_wr_cnt; i++) {
>  		struct dw_edma_region *ll_region = &chip->ll_region_wr[i];
>  		struct dw_edma_region *dt_region = &chip->dt_region_wr[i];
> -		struct dw_edma_block *ll_block = &vsec_data.ll_wr[i];
> -		struct dw_edma_block *dt_block = &vsec_data.dt_wr[i];
> +		struct dw_edma_block *ll_block = &vsec_data->ll_wr[i];
> +		struct dw_edma_block *dt_block = &vsec_data->dt_wr[i];
>  
>  		ll_region->vaddr.io = pcim_iomap_table(pdev)[ll_block->bar];
>  		if (!ll_region->vaddr.io)
> @@ -263,8 +267,8 @@ static int dw_edma_pcie_probe(struct pci_dev *pdev,
>  	for (i = 0; i < chip->ll_rd_cnt; i++) {
>  		struct dw_edma_region *ll_region = &chip->ll_region_rd[i];
>  		struct dw_edma_region *dt_region = &chip->dt_region_rd[i];
> -		struct dw_edma_block *ll_block = &vsec_data.ll_rd[i];
> -		struct dw_edma_block *dt_block = &vsec_data.dt_rd[i];
> +		struct dw_edma_block *ll_block = &vsec_data->ll_rd[i];
> +		struct dw_edma_block *dt_block = &vsec_data->dt_rd[i];
>  
>  		ll_region->vaddr.io = pcim_iomap_table(pdev)[ll_block->bar];
>  		if (!ll_region->vaddr.io)
> @@ -298,31 +302,31 @@ static int dw_edma_pcie_probe(struct pci_dev *pdev,
>  		pci_dbg(pdev, "Version:\tUnknown (0x%x)\n", chip->mf);
>  
>  	pci_dbg(pdev, "Registers:\tBAR=%u, off=0x%.8lx, sz=0x%zx bytes, addr(v=%p)\n",
> -		vsec_data.rg.bar, vsec_data.rg.off, vsec_data.rg.sz,
> +		vsec_data->rg.bar, vsec_data->rg.off, vsec_data->rg.sz,
>  		chip->reg_base);
>  
>  
>  	for (i = 0; i < chip->ll_wr_cnt; i++) {
>  		pci_dbg(pdev, "L. List:\tWRITE CH%.2u, BAR=%u, off=0x%.8lx, sz=0x%zx bytes, addr(v=%p, p=%pa)\n",
> -			i, vsec_data.ll_wr[i].bar,
> -			vsec_data.ll_wr[i].off, chip->ll_region_wr[i].sz,
> +			i, vsec_data->ll_wr[i].bar,
> +			vsec_data->ll_wr[i].off, chip->ll_region_wr[i].sz,
>  			chip->ll_region_wr[i].vaddr.io, &chip->ll_region_wr[i].paddr);
>  
>  		pci_dbg(pdev, "Data:\tWRITE CH%.2u, BAR=%u, off=0x%.8lx, sz=0x%zx bytes, addr(v=%p, p=%pa)\n",
> -			i, vsec_data.dt_wr[i].bar,
> -			vsec_data.dt_wr[i].off, chip->dt_region_wr[i].sz,
> +			i, vsec_data->dt_wr[i].bar,
> +			vsec_data->dt_wr[i].off, chip->dt_region_wr[i].sz,
>  			chip->dt_region_wr[i].vaddr.io, &chip->dt_region_wr[i].paddr);
>  	}
>  
>  	for (i = 0; i < chip->ll_rd_cnt; i++) {
>  		pci_dbg(pdev, "L. List:\tREAD CH%.2u, BAR=%u, off=0x%.8lx, sz=0x%zx bytes, addr(v=%p, p=%pa)\n",
> -			i, vsec_data.ll_rd[i].bar,
> -			vsec_data.ll_rd[i].off, chip->ll_region_rd[i].sz,
> +			i, vsec_data->ll_rd[i].bar,
> +			vsec_data->ll_rd[i].off, chip->ll_region_rd[i].sz,
>  			chip->ll_region_rd[i].vaddr.io, &chip->ll_region_rd[i].paddr);
>  
>  		pci_dbg(pdev, "Data:\tREAD CH%.2u, BAR=%u, off=0x%.8lx, sz=0x%zx bytes, addr(v=%p, p=%pa)\n",
> -			i, vsec_data.dt_rd[i].bar,
> -			vsec_data.dt_rd[i].off, chip->dt_region_rd[i].sz,
> +			i, vsec_data->dt_rd[i].bar,
> +			vsec_data->dt_rd[i].off, chip->dt_region_rd[i].sz,
>  			chip->dt_region_rd[i].vaddr.io, &chip->dt_region_rd[i].paddr);
>  	}
>  
> -- 
> 2.43.0
> 

-- 
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