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SubjectRe: WatchDog Driver Updates
On Sat, Apr 06, 2002 at 09:49:57PM -0500, Rob Radez wrote:
> I've put up a patch on against
> 2.4.19-pre5-ac3. The diff is 33k, and it affects 19 files in drivers/char/,

And the purpose of this patch is...

1. copy_to_user is like memcpy() - it takes two pointers and an integer
size. You're passing it two integers and a pointer:

static int wdt977_ioctl(... unsigned long arg)
if(copy_to_user(arg, &timer_alive, sizeof(timer_alive)))
return -EFAULT;
return 0;

2. sizeof(int) != sizeof(unsigned long). You've changed the ABI in an
unsafe manner on 64-bit machines. The ABI is defined by the ioctl
numbers, which specify an 'int' type.

3. copy_to_user of an int or unsigned long is a bit inefficient. Why
not use put_user to write an int or unsigned long?

4. Unless I'm missing something, WDIOC_GETSTATUS can only ever return
an indication that the timer is open/alive - it's set when the driver
is opened, and cleared when it is closed. Since you can't perform
an ioctl on a closed device, the times that you can perform the ioctl,
it'll always give you a non-zero result.

5. WDIOC_GETSTATUS is supposed to return the WDIOF_* flags. Returning
"watchdog active" as bit 0 causes it to indicate WDIOF_OVERHEAT.

Russell King ( The developer of ARM Linux

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