Re: [PATCH] USB: host: ehci: Add error handlinginehci_mxc_drv_probe()

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On 2020/5/8 22:31, Greg KH wrote:
On Fri, May 08, 2020 at 09:55:53PM +0800, Tang Bin wrote:
Hi, Greg:

On 2020/5/8 19:48, Greg KH wrote:
On Fri, May 08, 2020 at 07:44:53PM +0800, Tang Bin wrote:
The function ehci_mxc_drv_probe() does not perform sufficient error
checking after executing platform_get_irq(), thus fix it.

Fixes: 7e8d5cd93fa ("USB: Add EHCI support for MX27 and MX31 based boards")
Signed-off-by: Zhang Shengju <zhangshengju@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Tang Bin <tangbin@xxxxxxxxxxxxxxxxxxxx>
---
   drivers/usb/host/ehci-mxc.c | 2 ++
   1 file changed, 2 insertions(+)

diff --git a/drivers/usb/host/ehci-mxc.c b/drivers/usb/host/ehci-mxc.c
index a1eb5ee77..a0b42ba59 100644
--- a/drivers/usb/host/ehci-mxc.c
+++ b/drivers/usb/host/ehci-mxc.c
@@ -50,6 +50,8 @@ static int ehci_mxc_drv_probe(struct platform_device *pdev)
   	}
   	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return irq;
<= ?
In the file 'drivers/base/platform.c', the function platform_get_irq() is
explained and used as follows:

      * Gets an IRQ for a platform device and prints an error message if
finding the
      * IRQ fails. Device drivers should check the return value for errors so
as to
      * not pass a negative integer value to the request_irq() APIs.
      *
      * Example:
      *        int irq = platform_get_irq(pdev, 0);
      *        if (irq < 0)
      *            return irq;
      *
      * Return: IRQ number on success, negative error number on failure.

And in my hardware experiment, even if I set the irq failed deliberately in
the DTS, the returned value is negative instead of zero.
Please read the thread at
	https://lore.kernel.org/r/20200501224042.141366-1-helgaas%40kernel.org
for more details about this.

Great, It looks beautiful, finally someone took a knife to the file 'platform.c'.

I have been studied this place for a long time, and don't know what platform can return 0, which made me curious.

So the example should be:

     *        int irq = platform_get_irq(pdev, 0);
     *        if (irq <= 0)
     *            return irq;

Thanks,

Tang Bin






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