On Thu, 23 Aug 2012 19:51:26 +0530, Shubhrajyoti D wrote: > Prevent the NULL pointer access of pdev->dev in remove. The platform_device is anyways > deleted so remove platform_set_drvdata(pdev, NULL);. No, the platform device isn't deleted. The i2c adapters are deleted but the underlying platform device is not. > > [ 654.961761] Unable to handle kernel NULL pointer dereference at virtual address 00000070 > [ 654.970611] pgd = df254000 > [ 654.973480] [00000070] *pgd=9f1da831, *pte=00000000, *ppte=00000000 > [ 654.980163] Internal error: Oops: 17 [#1] SMP ARM > [ 654.985076] Modules linked in: > [ 654.988281] CPU: 1 Not tainted (3.6.0-rc1-00031-ge547de1-dirty #339) > [ 654.995330] PC is at omap_i2c_runtime_resume+0x8/0x148 > [ 655.000732] LR is at omap_i2c_runtime_resume+0x8/0x148 > > Signed-off-by: Shubhrajyoti D <shubhrajyoti@xxxxxx> > --- > drivers/i2c/busses/i2c-omap.c | 3 --- > 1 files changed, 0 insertions(+), 3 deletions(-) > > diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c > index 5d19a49..84fbef6 100644 > --- a/drivers/i2c/busses/i2c-omap.c > +++ b/drivers/i2c/busses/i2c-omap.c > @@ -1098,7 +1098,6 @@ err_unuse_clocks: > iounmap(dev->base); > pm_runtime_disable(&pdev->dev); > err_free_mem: > - platform_set_drvdata(pdev, NULL); > kfree(dev); > err_release_region: > release_mem_region(mem->start, resource_size(mem)); This can't be right. You're about to free the memory, so if anyone still can access it through platform_get_drvdata(), you're in trouble anyway. But I don't think this is the case here. > @@ -1112,8 +1111,6 @@ static int __devexit omap_i2c_remove(struct platform_device *pdev) > struct resource *mem; > int ret; > > - platform_set_drvdata(pdev, NULL); > - This OTOH is a good catch. But the problem isn't with calling platform_set_drvdata(pdev, NULL) per se. The problem is with calling it too early. It should be called after i2c_del_adapter(), and ideally before freeing the memory. > free_irq(dev->irq, dev); > i2c_del_adapter(&dev->adapter); > ret = pm_runtime_get_sync(&pdev->dev); -- Jean Delvare -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
