linux-kernel - Re: [PATCH v3] PCI: xilinx: Check for __get_free

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Date:   Tue, 26 Mar 2019 11:40:51 +0000
From:   Steven Price <steven.price@....com>
To:     Kangjie Lu <kjlu@....edu>
Cc:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        linux-pci@...r.kernel.org, Michal Simek <michal.simek@...inx.com>,
        linux-kernel@...r.kernel.org, pakki001@....edu,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v3] PCI: xilinx: Check for __get_free_pages() failure

On 25/03/2019 22:19, Kangjie Lu wrote:
> If __get_free_pages() fails, the patch returns -ENOMEM to avoid

As Bjorn suggested s/the patch returns/return/ would suffice and is
slightly easier to read. But I'm happy either way.

> NULL pointer dereference.
> 
> Signed-off-by: Kangjie Lu <kjlu@....edu>

Reviewed-by: Steven Price <steven.price@....com>

> ---
> v3: remove "unlikely", as suggested by Bjorn Helgaas.
> v2: caller is redefined to accept the error code, as suggested by
> Steven Price <steven.price@....com>
> ---
>  drivers/pci/controller/pcie-xilinx.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pci/controller/pcie-xilinx.c b/drivers/pci/controller/pcie-xilinx.c
> index 9bd1a35cd5d8..abc214e94f7c 100644
> --- a/drivers/pci/controller/pcie-xilinx.c
> +++ b/drivers/pci/controller/pcie-xilinx.c
> @@ -336,14 +336,19 @@ static const struct irq_domain_ops msi_domain_ops = {
>   * xilinx_pcie_enable_msi - Enable MSI support
>   * @port: PCIe port information
>   */
> -static void xilinx_pcie_enable_msi(struct xilinx_pcie_port *port)
> +static int xilinx_pcie_enable_msi(struct xilinx_pcie_port *port)
>  {
>  	phys_addr_t msg_addr;
>  
>  	port->msi_pages = __get_free_pages(GFP_KERNEL, 0);
> +	if (!port->msi_pages)
> +		return -ENOMEM;
> +
>  	msg_addr = virt_to_phys((void *)port->msi_pages);
>  	pcie_write(port, 0x0, XILINX_PCIE_REG_MSIBASE1);
>  	pcie_write(port, msg_addr, XILINX_PCIE_REG_MSIBASE2);
> +
> +	return 0;
>  }
>  
>  /* INTx Functions */
> @@ -498,6 +503,7 @@ static int xilinx_pcie_init_irq_domain(struct xilinx_pcie_port *port)
>  	struct device *dev = port->dev;
>  	struct device_node *node = dev->of_node;
>  	struct device_node *pcie_intc_node;
> +	int ret;
>  
>  	/* Setup INTx */
>  	pcie_intc_node = of_get_next_child(node, NULL);
> @@ -526,7 +532,9 @@ static int xilinx_pcie_init_irq_domain(struct xilinx_pcie_port *port)
>  			return -ENODEV;
>  		}
>  
> -		xilinx_pcie_enable_msi(port);
> +		ret = xilinx_pcie_enable_msi(port);
> +		if (ret)
> +			return ret;
>  	}
>  
>  	return 0;
>