Messages in this thread | | | Date | Mon, 2 Nov 2009 11:39:40 +0100 | From | Uwe Kleine-König <> | Subject | Re: Using statically allocated memory for platform_data. |
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Hello,
On Mon, Nov 02, 2009 at 11:23:16AM +0100, Antonio Ospite wrote: > Hi, > > I noted that in some mfd drivers (drivers/mfd/ezx-pcap.c and > drivers/mfd/da903x.c) there is code like this: > > static int __devinit pcap_add_subdev(struct pcap_chip *pcap, > struct pcap_subdev *subdev) > { > struct platform_device *pdev; > > pdev = platform_device_alloc(subdev->name, subdev->id); > pdev->dev.parent = &pcap->spi->dev; > pdev->dev.platform_data = subdev->platform_data; > > return platform_device_add(pdev); > } > > Note the _direct_assignment_ of platform data; then in board init code > there are often global struct pointers passed as subdev platform data, > see arch/arm/mach-pxa/em-x270.c::em_x270_da9030_subdevs for instance. > > In these cases, whenever the subdev platform device is unregistered, > the call to platform_device_release() tries to kfree the platform data, > and being it statically allocated memory this triggers a bug from SLAB: > kernel BUG at mm/slab.c:521! > In my case this prevented proper device poweroff. > > The question: should these mfd drivers use platform_device_add_data() > which allocates dynamic memory for *a copy* of platform data? Is this > simple solution acceptable even if there will be more memory used? If you move the original data lives in .init there is no duplication.
Best regards Uwe
-- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ | -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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